Medicinal Plants
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Medicinal plants, also called medicinal herbs, have been discovered and used in
traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) refers to the knowledge, skills, and practices rooted in the cultural beliefs of various societies, especially Indigenous groups, used for maintaining health and treatin ...
practices since prehistoric times.
Plants Plants are the eukaryotes that form the kingdom Plantae; they are predominantly photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars f ...
synthesize hundreds of chemical compounds for various functions, including
defense Defense or defence may refer to: Tactical, martial, and political acts or groups * Defense (military), forces primarily intended for warfare * Civil defense, the organizing of civilians to deal with emergencies or enemy attacks * Defense industr ...
and protection against
insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s,
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
,
diseases A disease is a particular abnormal condition that adversely affects the structure or function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical conditions that are asso ...
, against
parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...
s and
herbivorous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...
mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
s. The earliest historical records of herbs are found from the
Sumer Sumer () is the earliest known civilization, located in the historical region of southern Mesopotamia (now south-central Iraq), emerging during the Chalcolithic and Early Bronze Age, early Bronze Ages between the sixth and fifth millennium BC. ...
ian civilization, where hundreds of medicinal plants including
opium Opium (also known as poppy tears, or Lachryma papaveris) is the dried latex obtained from the seed Capsule (fruit), capsules of the opium poppy ''Papaver somniferum''. Approximately 12 percent of opium is made up of the analgesic alkaloid mor ...
are listed on clay tablets, . The
Ebers Papyrus The Ebers Papyrus, also known as Papyrus Ebers, is an Egyptian medical papyrus of herbal knowledge dating to (the late Second Intermediate Period or early New Kingdom). Among the oldest and most important medical papyri of Ancient Egypt, it ...
from
ancient Egypt Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower E ...
, , describes over 850 plant medicines. The Greek physician
Dioscorides Pedanius Dioscorides (, ; 40–90 AD), "the father of pharmacognosy", was a Greek physician, pharmacologist, botanist, and author of (in the original , , both meaning "On Materia medica, Medical Material") , a 5-volume Greek encyclopedic phar ...
, who worked in the Roman army, documented over 1000 recipes for medicines using over 600 medicinal plants in , ; this formed the basis of
pharmacopoeia A pharmacopoeia, pharmacopeia, or pharmacopoea (or the typographically obsolete rendering, ''pharmacopœia''), meaning "drug-making", in its modern technical sense, is a reference work containing directions for the identification of compound med ...
s for some 1500 years. Drug research sometimes makes use of
ethnobotany Ethnobotany is an interdisciplinary field at the interface of natural and social sciences that studies the relationships between humans and plants. It focuses on traditional knowledge of how plants are used, managed, and perceived in human socie ...
to search for pharmacologically active substances, and this approach has yielded hundreds of useful compounds. These include the common drugs
aspirin Aspirin () is the genericized trademark for acetylsalicylic acid (ASA), a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and inflammation, and as an antithrombotic. Specific inflammatory conditions that aspirin is ...
,
digoxin Digoxin (better known as digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart disease, heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. ...
,
quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to ''Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...
, and opium. The compounds found in plants are diverse, with most in four biochemical classes:
alkaloid Alkaloids are a broad class of natural product, naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large varie ...
s,
glycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...
s,
polyphenol Polyphenols () are a large family of naturally occurring phenols. They are abundant in plants and structurally diverse. Polyphenols include phenolic acids, flavonoids, tannic acid, and ellagitannin, some of which have been used historically as ...
s, and
terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predomi ...
s. Few of these are scientifically confirmed as medicines or used in conventional medicine. Medicinal plants are widely used as folk medicine in non-industrialized societies, mainly because they are readily available and cheaper than modern medicines. In many countries, there is little regulation of traditional medicine, but the
World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...
coordinates a network to encourage safe and rational use. The botanical herbal market has been criticized for being poorly regulated and containing
placebo A placebo ( ) can be roughly defined as a sham medical treatment. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures. Placebos are used in randomized clinical trials ...
and
pseudoscience Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable cl ...
products with no scientific research to support their medical claims. Medicinal plants face both general threats, such as
climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
and
habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...
, and the specific threat of over-collection to meet market demand.


History


Prehistoric times

Plants, including many now used as culinary herbs and
spice In the culinary arts, a spice is any seed, fruit, root, Bark (botany), bark, or other plant substance in a form primarily used for flavoring or coloring food. Spices are distinguished from herbs, which are the leaves, flowers, or stems of pl ...
s, have been used as medicines, not necessarily effectively, from prehistoric times. Spices have been used partly to counter
food spoilage Food spoilage is the process whereby food becomes unsuitable to ingest by a person; it is a matter of food safety. Bacteria and various fungi are the causes of spoilage, and can create serious consequences for consumers, but there are preventive ...
bacteria, especially in hot climates, and especially in meat dishes that spoil more readily. Angiosperms (
flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...
s) were the original source of most plant medicines. Human settlements are often surrounded by weeds used as
herbal medicine Herbal medicine (also called herbalism, phytomedicine or phytotherapy) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. Scientific evidence for the effectiveness of many herbal treatments ...
s, such as
nettle Nettle refers to plants with stinging hairs, particularly those of the genus '' Urtica''. It can also refer to plants which resemble ''Urtica'' species in appearance but do not have stinging hairs. Plants called "nettle" include: * ball nettle ...
,
dandelion ''Taraxacum'' () is a genus of flowering plants in the family Asteraceae, which consists of species commonly known as dandelions. The scientific and hobby study of the genus is known as taraxacology. The genus has a near-cosmopolitan distribu ...
and
chickweed ''Stellaria media'', chickweed, is an annual flowering plant in the family Caryophyllaceae. It is native to Eurasia and naturalized throughout the world, where it is a weed of waste ground, farmland and gardens. It is sometimes grown as a salad ...
. Humans were not alone in using herbs: some animals, such as non-human
primate Primates is an order (biology), order of mammals, which is further divided into the Strepsirrhini, strepsirrhines, which include lemurs, galagos, and Lorisidae, lorisids; and the Haplorhini, haplorhines, which include Tarsiiformes, tarsiers a ...
s,
monarch butterflies The monarch butterfly or simply monarch (''Danaus plexippus'') is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae. Other common names, depending on region, include milkweed, common tiger, wanderer, and black-veined brown. ...
and
sheep Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to d ...
ingest plants when they are ill. Samples from prehistoric burial sites indicate that Paleolithic peoples consumed plants. For instance, a 60,000-year-old Neanderthal burial site, " Shanidar IV", in northern Iraq yielded pollen from eight plant species. At
Taforalt Taforalt, or Grotte des Pigeons, is a cave in the province of Berkane, Aït Iznasen region, Morocco, possibly the oldest cemetery in North Africa. It contained at least 34 Iberomaurusian adolescent and adult human skeletons, as well as young ...
cave, Morocco, 15,000-year-old remains of ephedra were found inside a tomb, indicating its possible role in funeral rites. A mushroom found in the personal effects of ''
Ötzi the Iceman Ötzi, also called The Iceman, is the natural mummy of a man who lived between 3350 and 3105 BC. Ötzi's remains were discovered on 19 September 1991, in the Ötztal Alps (hence the nickname "Ötzi", ) at the Austria–Italy border. He ...
'', whose body was frozen in the
Ötztal Alps The Ötztal Alps (, ) are a mountain range in the Central Eastern Alps, in the Tyrol (state), State of Tyrol in western Austria and the South Tyrol, Province of South Tyrol in northern Italy. Geography The Ötztal Alps are arrayed at the head of ...
for more than 5,000 years, may have been used against whipworm.


Ancient times

In ancient
Sumer Sumer () is the earliest known civilization, located in the historical region of southern Mesopotamia (now south-central Iraq), emerging during the Chalcolithic and Early Bronze Age, early Bronze Ages between the sixth and fifth millennium BC. ...
ia, hundreds of medicinal plants including
myrrh Myrrh (; from an unidentified ancient Semitic language, see '' § Etymology'') is a gum-resin extracted from a few small, thorny tree species of the '' Commiphora'' genus, belonging to the Burseraceae family. Myrrh resin has been used ...
and opium are listed on clay tablets from around 3000 BC. The
ancient Egyptian Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower E ...
Ebers Papyrus The Ebers Papyrus, also known as Papyrus Ebers, is an Egyptian medical papyrus of herbal knowledge dating to (the late Second Intermediate Period or early New Kingdom). Among the oldest and most important medical papyri of Ancient Egypt, it ...
lists over 800 plant medicines such as
aloe ''Aloe'' (; also written ''Aloë'') is a genus containing over 650 species of flowering plant, flowering succulent plant, succulent plants.WFO (2022): Aloe L. Published on the Internet;http://www.worldfloraonline.org/taxon/wfo-4000001341. Acc ...
,
cannabis ''Cannabis'' () is a genus of flowering plants in the family Cannabaceae that is widely accepted as being indigenous to and originating from the continent of Asia. However, the number of species is disputed, with as many as three species be ...
, castor bean,
garlic Garlic (''Allium sativum'') is a species of bulbous flowering plants in the genus '' Allium''. Its close relatives include the onion, shallot, leek, chives, Welsh onion, and Chinese onion. Garlic is native to central and south Asia, str ...
,
juniper Junipers are coniferous trees and shrubs in the genus ''Juniperus'' ( ) of the cypress family Cupressaceae. Depending on the taxonomy, between 50 and 67 species of junipers are widely distributed throughout the Northern Hemisphere as far south ...
, and
mandrake A mandrake is the root of a plant, historically derived either from plants of the genus '' Mandragora'' (in the family Solanaceae) found in the Mediterranean region, or from other species, such as '' Bryonia alba'' (the English mandrake, in the ...
. In antiquity, various cultures across Europe, including the Romans, Celts, and Nordic peoples, also practiced herbal medicine as a significant component of their healing traditions. The Romans had a rich tradition of herbal medicine, drawing upon knowledge inherited from the Greeks and expanding upon it. Notable works include those of Pedanius Dioscorides, whose "De Materia Medica" served as a comprehensive guide to medicinal plants and remained influential for centuries. Additionally, Pliny the Elder's "Naturalis Historia" contains valuable insights into Roman medical plant practices Among the Celtic peoples of ancient Europe, herbalism played a vital role in both medicine and spirituality. Druids, the religious leaders of the Celts, were reputed to possess deep knowledge of plants and their medicinal properties. Although written records are scarce, archaeological evidence, such as the discovery of medicinal plants at Celtic sites, provides insight into their herbal practices In the Nordic regions, including Scandinavia and parts of Germany, herbal medicine was also prevalent in ancient times. The Norse sagas and Eddic poetry often mention the use of herbs for healing purposes. Additionally, archaeological findings, such as the remains of medicinal plants in Viking-age graves, attest to the importance of herbal remedies in Nordic culture From ancient times to the present, Ayurvedic medicine as documented in the
Atharva Veda The Atharvaveda or Atharva Veda (, , from ''wikt:अथर्वन्, अथर्वन्'', "priest" and ''wikt:वेद, वेद'', "knowledge") or is the "knowledge storehouse of ''wikt:अथर्वन्, atharvans'', the proced ...
, the
Rig Veda The ''Rigveda'' or ''Rig Veda'' (, , from wikt:ऋच्, ऋच्, "praise" and wikt:वेद, वेद, "knowledge") is an ancient Indian Miscellany, collection of Vedic Sanskrit hymns (''sūktas''). It is one of the four sacred canoni ...
and the
Sushruta Samhita The ''Sushruta Samhita'' (, ) is an ancient Sanskrit text on medicine and one of the most important such treatises on this subject to survive from the ancient world. The ''Compendium of Sushruta, Suśruta'' is one of the foundational texts of ...
has used hundreds of herbs and spices, such as
turmeric Turmeric (), or ''Curcuma longa'' (), is a flowering plant in the ginger family Zingiberaceae. It is a perennial, rhizomatous, herbaceous plant native to the Indian subcontinent and Southeast Asia that requires temperatures between and high ...
, which contains
curcumin Curcumin is a bright yellow chemical produced by plants of the ''Curcuma longa'' species. It is the principal curcuminoid of turmeric (''Curcuma longa''), a member of the ginger family, Zingiberaceae. It is sold as a herbal supplement, cosmetic ...
. The Chinese pharmacopoeia, the ''
Shennong Ben Cao Jing ''Shennong Bencaojing'' (also ''Classic of the Materia Medica'' or ''Shen-nong's Herbal Classics'' and ''Shen-nung Pen-tsao Ching''; ) is a Chinese book on agriculture and medicinal plants, traditionally attributed to Shennong. Researchers belie ...
'' records plant medicines such as
chaulmoogra ''Hydnocarpus pentandrus'' (previously ''Hydnocarpus wightianus'') or chaulmoogra is a medium-sized tree in the family Achariaceae. This dioecious tree grows up to 10m height, in moist deciduous forests of Western Ghats in India. ''Hydnocarpu ...
for leprosy, ephedra, and
hemp Hemp, or industrial hemp, is a plant in the botanical class of ''Cannabis sativa'' cultivars grown specifically for industrial and consumable use. It can be used to make a wide range of products. Along with bamboo, hemp is among the fastest ...
. This was expanded in the
Tang dynasty The Tang dynasty (, ; zh, c=唐朝), or the Tang Empire, was an Dynasties of China, imperial dynasty of China that ruled from 618 to 907, with an Wu Zhou, interregnum between 690 and 705. It was preceded by the Sui dynasty and followed ...
'' Yaoxing Lun''. In the fourth century BC,
Aristotle Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...
's pupil
Theophrastus Theophrastus (; ; c. 371 – c. 287 BC) was an ancient Greek Philosophy, philosopher and Natural history, naturalist. A native of Eresos in Lesbos, he was Aristotle's close colleague and successor as head of the Lyceum (classical), Lyceum, the ...
wrote the first systematic botany text, '' Historia plantarum''. In around 60 AD, the Greek physician
Pedanius Dioscorides Pedanius Dioscorides (, ; 40–90 AD), "the father of pharmacognosy", was a Greek physician, pharmacologist, botanist, and author of (in the original , , both meaning "On Medical Material") , a 5-volume Greek encyclopedic pharmacopeia on he ...
, working for the Roman army, documented over 1000 recipes for medicines using over 600 medicinal plants in . The book remained the authoritative reference on herbalism for over 1500 years, into the seventeenth century.


Middle Ages

During the Middle Ages, herbalism continued to flourish across Europe, with distinct traditions emerging in various regions, often influenced by cultural, religious, indigenous, and geographical factors. In the
Early Middle Ages The Early Middle Ages (or early medieval period), sometimes controversially referred to as the Dark Ages (historiography), Dark Ages, is typically regarded by historians as lasting from the late 5th to the 10th century. They marked the start o ...
, Benedictine monasteries preserved medical knowledge in
Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
, translating and copying classical texts and maintaining herb gardens.
Hildegard of Bingen Hildegard of Bingen Benedictines, OSB (, ; ; 17 September 1179), also known as the Sibyl of the Rhine, was a German Benedictines, Benedictine abbess and polymath active as a writer, composer, philosopher, Christian mysticism, mystic, visiona ...
wrote ''Causae et Curae'' ("Causes and Cures") on medicine. In France, herbalism thrived alongside the practice of medieval medicine, which combined elements of Ancient Greek and Roman traditions. Catholic monastic orders played a significant role in preserving and expanding herbal knowledge. Manuscripts like the "Tractatus de Herbis" from the 15th century depict French herbal remedies and their uses. Monasteries and convents served as centers of learning, where monks and nuns cultivated medicinal gardens. Likewise, in Italy, herbalism flourished with contribution Italian physicians like Matthaeus Platearius who compiled herbal manuscripts, such as the "Circa Instans," which served as practical guides for herbal remedies. In the Iberian Peninsula, the regions of the North remained independent during the period of Islamic occupation, and retained their traditional and indigenous medical practices. Galicia and Asturias, possessed a rich herbal heritage shaped by its Celtic and Roman influences. The Galician people were known for their strong connection to the land and nature and preserved botanical knowledge, with healers, known as "curandeiros" or "meigas," who relied on local plants for healing purposes The Asturian landscape, characterized by lush forests and mountainous terrain, provided a rich source of medicinal herbs used in traditional healing practices, with "yerbatos," who possessed extensive knowledge of local plants and their medicinal properties Barcelona, located in the Catalonia region of northeastern Spain, was a hub of cultural exchange during the Middle Ages, fostering the preservation and dissemination of medical knowledge. Catalan herbalists, known as "herbolarios," compiled manuscripts detailing the properties and uses of medicinal plants found in the region. The University of Barcelona, founded in 1450, played a pivotal role in advancing herbal medicine through its botanical gardens and academic pursuits. In Scotland and England, herbalism was deeply rooted in folk traditions and influenced by Celtic, Anglo-Saxon, and Norse practices. Herbal knowledge was passed down through generations, often by wise women known as "cunning folk." The "Physicians of Myddfai," a Welsh herbal manuscript from the 13th century, reflects the blending of Celtic and Christian beliefs in herbal medicine. In the
Islamic Golden Age The Islamic Golden Age was a period of scientific, economic, and cultural flourishing in the history of Islam, traditionally dated from the 8th century to the 13th century. This period is traditionally understood to have begun during the reign o ...
, scholars translated many classical Greek texts including Dioscorides into
Arabic Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns lang ...
, adding their own commentaries. Herbalism flourished in the Islamic world, particularly in
Baghdad Baghdad ( or ; , ) is the capital and List of largest cities of Iraq, largest city of Iraq, located along the Tigris in the central part of the country. With a population exceeding 7 million, it ranks among the List of largest cities in the A ...
and in
Al-Andalus Al-Andalus () was the Muslim-ruled area of the Iberian Peninsula. The name refers to the different Muslim states that controlled these territories at various times between 711 and 1492. At its greatest geographical extent, it occupied most o ...
. Among many works on medicinal plants, Abulcasis (936–1013) of Cordoba wrote ''The Book of Simples'', and Ibn al-Baitar (1197–1248) recorded hundreds of medicinal herbs such as ''Aconitum'', nux vomica, and
tamarind Tamarind (''Tamarindus indica'') is a Legume, leguminous tree bearing edible fruit that is indigenous to tropical Africa and naturalized in Asia. The genus ''Tamarindus'' is monotypic taxon, monotypic, meaning that it contains only this spe ...
in his ''Corpus of Simples''.
Avicenna Ibn Sina ( – 22 June 1037), commonly known in the West as Avicenna ( ), was a preeminent philosopher and physician of the Muslim world, flourishing during the Islamic Golden Age, serving in the courts of various Iranian peoples, Iranian ...
included many plants in his 1025 ''
The Canon of Medicine ''The Canon of Medicine'' () is an encyclopedia of medicine in five books compiled by Avicenna (, ibn Sina) and completed in 1025. It is among the most influential works of its time. It presents an overview of the contemporary medical knowle ...
''. Abu-Rayhan Biruni,
Ibn Zuhr Abū Marwān ‘Abd al-Malik ibn Zuhr (), traditionally known by his Latinized name Avenzoar (; 1094–1162), was an Arab physician, surgeon, and poet. He was born at Seville in medieval Andalusia (present-day Spain), was a contemporary of A ...
, Peter of Spain, and John of St Amand wrote further
pharmacopoeia A pharmacopoeia, pharmacopeia, or pharmacopoea (or the typographically obsolete rendering, ''pharmacopœia''), meaning "drug-making", in its modern technical sense, is a reference work containing directions for the identification of compound med ...
s.


Early Modern

The
Early Modern The early modern period is a Periodization, historical period that is defined either as part of or as immediately preceding the modern period, with divisions based primarily on the history of Europe and the broader concept of modernity. There i ...
period saw the flourishing of illustrated
herbal A herbal is a book containing the names and descriptions of plants, usually with information on their medicinal, Herbal tonic, tonic, culinary, toxic, hallucinatory, aromatic, or Magic (paranormal), magical powers, and the legends associated wi ...
s across Europe, starting with the 1526 '' Grete Herball''.
John Gerard John Gerard (also John Gerarde, 1545–1612) was an English herbalist with a large garden in Holborn, now part of London. His 1,484-page illustrated ''Herball, or Generall Historie of Plantes'', first published in 1597, became a popular garde ...
wrote his famous ''The Herball or General History of Plants'' in 1597, based on
Rembert Dodoens Rembert Dodoens (born Rembert van Joenckema, 29 June 1517 – 10 March 1585) was a Flemish people, Flemish physician and botanist, also known under his Latinization (literature), Latinized name Rembertus Dodonaeus. He has been called the father o ...
, and
Nicholas Culpeper Nicholas Culpeper (18 October 1616 – 10 January 1654) was an English botanist, herbalist, physician and astrologer.Patrick Curry: "Culpeper, Nicholas (1616–1654)", ''Oxford Dictionary of National Biography'' (Oxford, UK: OUP, 2004) His boo ...
published his ''The English Physician Enlarged''. Many new plant medicines arrived in Europe as products of Early Modern exploration and the resulting
Columbian Exchange The Columbian exchange, also known as the Columbian interchange, was the widespread transfer of plants, animals, and diseases between the New World (the Americas) in the Western Hemisphere, and the Old World (Afro-Eurasia) in the Eastern Hemis ...
, in which livestock, crops and technologies were transferred between the Old World and the Americas in the 15th and 16th centuries. Medicinal herbs arriving in the Americas included garlic, ginger, and turmeric; coffee, tobacco and coca travelled in the other direction. In Mexico, the sixteenth century ''Badianus Manuscript'' described medicinal plants available in Central America.


19th and 20th centuries

The place of plants in medicine was radically altered in the 19th century by the application of
chemical analysis Analytical chemistry studies and uses instruments and methods to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separa ...
.
Alkaloid Alkaloids are a broad class of natural product, naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large varie ...
s were isolated from a succession of medicinal plants, starting with
morphine Morphine, formerly also called morphia, is an opiate that is found naturally in opium, a dark brown resin produced by drying the latex of opium poppies (''Papaver somniferum''). It is mainly used as an analgesic (pain medication). There are ...
from the
poppy A poppy is a flowering plant in the subfamily Papaveroideae of the family Papaveraceae. Poppies are herbaceous plants, often grown for their colourful flowers. One species of poppy, '' Papaver somniferum'', is the source of the narcotic drug ...
in 1806, and soon followed by ipecacuanha and
strychnos ''Strychnos'' is a genus of flowering plants, belonging to the family Loganiaceae (sometimes Strychnaceae). The genus includes about 200 accepted species of trees and lianas. The genus is widely distributed around the world's tropics and is n ...
in 1817,
quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to ''Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...
from the
cinchona ''Cinchona'' (pronounced or ) is a genus of flowering plants in the family Rubiaceae containing at least 23 species of trees and shrubs. All are native to the Tropical Andes, tropical Andean forests of western South America. A few species are ...
tree, and then many others. As chemistry progressed, additional classes of potentially active substances were discovered in plants. Commercial extraction of purified alkaloids including morphine began at Merck in 1826.
Synthesis Synthesis or synthesize may refer to: Science Chemistry and biochemistry *Chemical synthesis, the execution of chemical reactions to form a more complex molecule from chemical precursors **Organic synthesis, the chemical synthesis of organi ...
of a substance first discovered in a medicinal plant began with salicylic acid in 1853. Around the end of the 19th century, the mood of pharmacy turned against medicinal plants, as
enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
s often modified the active ingredients when whole plants were dried, and alkaloids and glycosides purified from plant material started to be preferred. Drug discovery from plants continued to be important through the 20th century and into the 21st, with important anti-cancer drugs from yew and Madagascar periwinkle.


Context

Medicinal plants are used with the intention of maintaining health, to be administered for a specific condition, or both, whether in
modern medicine Medicine is the science and practice of caring for patients, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pract ...
or in traditional medicine. The
Food and Agriculture Organization The Food and Agriculture Organization of the United Nations; . (FAO) is a specialized agency of the United Nations that leads international efforts to defeat hunger and improve nutrition and food security. Its Latin motto, , translates ...
estimated in 2002 that over 50,000 medicinal plants are used across the world. The
Royal Botanic Gardens, Kew Royal Botanic Gardens, Kew is a non-departmental public body in the United Kingdom sponsored by the Department for Environment, Food and Rural Affairs. An internationally important botanical research and education institution, it employs 1,10 ...
more conservatively estimated in 2016 that 17,810 plant species have a medicinal use, out of some 30,000 plants for which a use of any kind is documented. In modern medicine, around a quarter of the drugs prescribed to patients are derived from medicinal plants, and they are rigorously tested. In other systems of medicine, medicinal plants may constitute the majority of what are often informal attempted treatments, not tested scientifically. The
World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...
estimates, without reliable data, that some 80 percent of the world's population depends mainly on traditional medicine (including but not limited to plants); perhaps some two billion people are largely reliant on medicinal plants. The use of plant-based materials including herbal or natural health products with supposed health benefits, is increasing in developed countries. This brings attendant risks of toxicity and other effects on human health, despite the safe image of herbal remedies. Herbal medicines have been in use since long before modern medicine existed; there was and often still is little or no knowledge of the pharmacological basis of their actions, if any, or of their safety. The World Health Organization formulated a policy on traditional medicine in 1991, and since then has published guidelines for them, with a series of monographs on widely used herbal medicines. Medicinal plants may provide three main kinds of benefit: health benefits to the people who consume them as medicines; financial benefits to people who harvest, process, and distribute them for sale; and society-wide benefits, such as job opportunities, taxation income, and a healthier labour force. However, development of plants or extracts having potential medicinal uses is blunted by weak scientific evidence, poor practices in the process of
drug development Drug development is the process of bringing a new pharmaceutical drug to the market once a lead compound has been identified through the process of drug discovery. It includes preclinical research on microorganisms and animals, filing for regu ...
, and insufficient financing.


Trade

The markets for medicinal and
aromatic In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated system, conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugati ...
plants are grouped in manufacturing categories of pharmaceuticals and dietary supplements, food and beverages, personal care products and cosmetics, with the pharmaceutical and supplement category accounting for about 60% of the total. As of 2023 by one estimate, the global market was US$68 billion per year, growing by 10-20% annually. China and India are the leading producers of natural products, and are also the leading exporters and domestic consumers. Major importers include the United States, the European Union, and Japan.


Phytochemical basis

All plants produce chemical compounds which give them an
evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...
ary advantage, such as defending against herbivores or, in the example of salicylic acid, as a
hormone A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physio ...
in plant defenses. These phytochemicals have potential for use as drugs, and the content and known pharmacological activity of these substances in medicinal plants is the scientific basis for their use in modern medicine, if scientifically confirmed. For instance, daffodils ('' Narcissus'') contain nine groups of alkaloids including
galantamine Galantamine is a type of acetylcholinesterase inhibitor. It is an alkaloid extracted from the bulbs and flowers of ''Galanthus nivalis'' (common snowdrop), '' Galanthus caucasicus'' (Caucasian snowdrop), '' Galanthus woronowii'' (Voronov's snow ...
, licensed for use against
Alzheimer's disease Alzheimer's disease (AD) is a neurodegenerative disease and the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems wit ...
. The alkaloids are bitter-tasting and toxic, and concentrated in the parts of the plant such as the stem most likely to be eaten by herbivores; they may also protect against
parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...
s. Modern knowledge of medicinal plants is being systematised in the Medicinal Plant Transcriptomics Database, which by 2011 provided a sequence reference for the
transcriptome The transcriptome is the set of all RNA transcripts, including coding and non-coding, in an individual or a population of cells. The term can also sometimes be used to refer to all RNAs, or just mRNA, depending on the particular experiment. The ...
of some thirty species. Major classes of plant
phytochemical Phytochemicals are naturally-occurring chemicals present in or extracted from plants. Some phytochemicals are nutrients for the plant, while others are metabolites produced to enhance plant survivability and reproduction. The fields of ext ...
s are described below, with examples of plants that contain them.


Alkaloids

Alkaloids Alkaloids are a broad class of naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large variety of organisms i ...
are bitter-tasting chemicals, very widespread in nature, and often toxic, found in many medicinal plants. There are several classes with different modes of action as drugs, both recreational and pharmaceutical. Medicines of different classes include
atropine Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically give ...
, scopolamine, and
hyoscyamine Hyoscyamine (also known as daturine or duboisine) is a naturally occurring tropane alkaloid and plant toxin. It is a secondary metabolite found in certain plants of the family Solanaceae, including Hyoscyamus niger, henbane, Mandragora officina ...
(all from
nightshade Solanaceae (), commonly known as the nightshades, is a family of flowering plants in the order Solanales. It contains approximately 2,700 species, several of which are used as agricultural crops, medicinal plants, and ornamental plants. Many me ...
), the traditional medicine
berberine Berberine is a Quaternary ammonium cation, quaternary ammonium salt from the protoberberine group of benzylisoquinoline alkaloids, occurring naturally as a secondary metabolite in some plants including species of ''Berberis'', from which its name ...
(from plants such as ''
Berberis ''Berberis'' (), commonly known as barberry, is a large genus of deciduous and evergreen shrubs from tall, found throughout temperate and subtropical regions of the world (apart from Australia). Species diversity is greatest in South America a ...
'' and '' Mahonia''),
caffeine Caffeine is a central nervous system (CNS) stimulant of the methylxanthine chemical classification, class and is the most commonly consumed Psychoactive drug, psychoactive substance globally. It is mainly used for its eugeroic (wakefulness pr ...
(''
Coffea ''Coffea'' is a genus of flowering plants in the family Rubiaceae. ''Coffea'' species are shrubs or small trees native to tropical and southern Africa and tropical Asia. The seeds of some species, called coffee beans, are used to flavor variou ...
''),
cocaine Cocaine is a tropane alkaloid and central nervous system stimulant, derived primarily from the leaves of two South American coca plants, ''Erythroxylum coca'' and ''Erythroxylum novogranatense, E. novogranatense'', which are cultivated a ...
(''
Coca Coca is any of the four cultivated plants in the family Erythroxylaceae, native to western South America. Coca is known worldwide for its psychoactive alkaloid, cocaine. Coca leaves contain cocaine which acts as a mild stimulant when chewed or ...
''),
ephedrine Ephedrine is a central nervous system (CNS) stimulant and sympathomimetic agent that is often used to prevent hypotension, low blood pressure during anesthesia. It has also been used for asthma, narcolepsy, and obesity but is not the preferred ...
('' Ephedra''), morphine (opium poppy),
nicotine Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...
(
tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...
),
reserpine Reserpine is a drug that is used for the treatment of hypertension, high blood pressure, usually in combination with a thiazide diuretic or vasodilator. Large clinical trials have shown that combined treatment with reserpine plus a thiazide diur ...
(''
Rauvolfia serpentina ''Rauvolfia serpentina'', the Indian snakeroot, devil pepper, serpentine wood, Sarpagandha (as known locally) or Chandrika, is a species of flower in the milkweed family Apocynaceae. It is native to the Indian subcontinent and East Asia (from Ind ...
''),
quinidine Quinidine is a class I antiarrhythmic agent, class IA antiarrhythmic agent used to treat heart rhythm disturbances. It is a diastereomer of Antimalarial medication, antimalarial agent quinine, originally derived from the bark of the cinchona tre ...
and
quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to ''Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...
(''
Cinchona ''Cinchona'' (pronounced or ) is a genus of flowering plants in the family Rubiaceae containing at least 23 species of trees and shrubs. All are native to the Tropical Andes, tropical Andean forests of western South America. A few species are ...
''),
vincamine Vincamine is a monoterpenoid indole alkaloid found in the leaves of ''Vinca minor'' (lesser periwinkle), comprising about 25–65% of its indole alkaloids by weight. It can also be synthesized from related alkaloids. Uses Vincamine is sold in ...
(''
Vinca minor ''Vinca minor'' (common names lesser periwinkle or dwarf periwinkle) is a species of flowering plant in the dogbane family, native to central and southern Europe. Other vernacular names used in cultivation include small periwinkle, common peri ...
''), and
vincristine Vincristine, also known as leurocristine and sold under the brand name Oncovin among others, is a chemotherapy medication used to treat a number of types of cancer. This includes acute lymphocytic leukemia, acute myeloid leukemia, Hodgkin lym ...
('' Catharanthus roseus''). File:Opium poppy.jpg, The opium poppy ''
Papaver somniferum ''Papaver somniferum'', commonly known as the opium poppy or breadseed poppy, is a species of flowering plant in the family Papaveraceae. It is the species of plant from which both opium and poppy seeds are derived and is also a valuable orname ...
'' is the source of the
alkaloids Alkaloids are a broad class of naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large variety of organisms i ...
morphine and
codeine Codeine is an opiate and prodrug of morphine mainly used to treat pain, coughing, and diarrhea. It is also commonly used as a recreational drug. It is found naturally in the sap of the opium poppy, ''Papaver somniferum''. It is typically use ...
. File:Nicotine.svg, The alkaloid
nicotine Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...
from
tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...
binds directly to the body's
Nicotinic acetylcholine receptor Nicotinic acetylcholine receptors, or nAChRs, are Receptor (biochemistry), receptor polypeptides that respond to the neurotransmitter acetylcholine. Nicotinic receptors also respond to drugs such as the agonist nicotine. They are found in the c ...
s, accounting for its pharmacological effects. File:Koeh-018.jpg, Deadly nightshade, ''Atropa belladonna'', yields
tropane alkaloid Tropane alkaloids are a class of bicyclic .2.1alkaloids and secondary metabolites that contain a tropane ring in their chemical structure. Tropane alkaloids occur naturally in many members of the plant family Solanaceae. Certain tropane alkaloi ...
s including
atropine Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically give ...
, scopolamine and
hyoscyamine Hyoscyamine (also known as daturine or duboisine) is a naturally occurring tropane alkaloid and plant toxin. It is a secondary metabolite found in certain plants of the family Solanaceae, including Hyoscyamus niger, henbane, Mandragora officina ...
.


Glycosides

Anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic hydrocarbon, aromatic organic compound with formula . Several isomers exist but these terms usually refer to 9,10-anthraquinone (IUPAC: 9,10-dioxoanthracene) wherein th ...
glycosides In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...
are found in medicinal plants such as
rhubarb Rhubarb is the fleshy, edible stalks ( petioles) of species and hybrids (culinary rhubarb) of ''Rheum'' in the family Polygonaceae, which are cooked and used for food. The plant is a herbaceous perennial that grows from short, thick rhizomes. ...
, cascara, and Alexandrian senna. Plant-based
laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lubri ...
s made from such plants include senna,
rhubarb Rhubarb is the fleshy, edible stalks ( petioles) of species and hybrids (culinary rhubarb) of ''Rheum'' in the family Polygonaceae, which are cooked and used for food. The plant is a herbaceous perennial that grows from short, thick rhizomes. ...
and ''
Aloe ''Aloe'' (; also written ''Aloë'') is a genus containing over 650 species of flowering plant, flowering succulent plant, succulent plants.WFO (2022): Aloe L. Published on the Internet;http://www.worldfloraonline.org/taxon/wfo-4000001341. Acc ...
''. The
cardiac glycoside Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses include treatments for ...
s are powerful drugs from medicinal plants including
foxglove ''Digitalis'' ( or ) is a genus of about 20 species of herbaceous perennial plants, shrubs, and biennials, commonly called foxgloves. ''Digitalis'' is native to Europe, Western Asia, and northwestern Africa. The flowers are tubular in sha ...
and
lily of the valley Lily of the valley (''Convallaria majalis'' ), sometimes written lily-of-the-valley, is a woodland flowering plant with sweetly scented, pendent, bell-shaped white flowers borne in sprays in spring. It is native throughout the cool temperate No ...
. They include
digoxin Digoxin (better known as digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart disease, heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. ...
and
digitoxin Digitoxin is a cardiac glycoside used for the treatment of heart failure and certain kinds of heart arrhythmia. It is a phytosteroid and is similar in structure and effects to digoxin, though the effects are longer-lasting. Unlike digoxin, whic ...
which support the beating of the heart, and act as
diuretic A diuretic () is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. A diuretic tablet is sometimes colloquially called a water tablet. There are several categories of diuretics. All diuretics ...
s. File:Senna alexandrina Mill.-Cassia angustifolia L. (Senna Plant).jpg, '' Senna alexandrina'', containing anthraquinone glycosides, has been used as a
laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lubri ...
for millennia. Digitalis purpurea2.jpg, The
foxglove ''Digitalis'' ( or ) is a genus of about 20 species of herbaceous perennial plants, shrubs, and biennials, commonly called foxgloves. ''Digitalis'' is native to Europe, Western Asia, and northwestern Africa. The flowers are tubular in sha ...
, ''Digitalis purpurea'', contains
digoxin Digoxin (better known as digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart disease, heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. ...
, a
cardiac glycoside Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses include treatments for ...
. The plant was used on heart conditions long before the glycoside was identified. File:Digoxin.svg,
Digoxin Digoxin (better known as digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart disease, heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. ...
is used to treat
atrial fibrillation Atrial fibrillation (AF, AFib or A-fib) is an Heart arrhythmia, abnormal heart rhythm (arrhythmia) characterized by fibrillation, rapid and irregular beating of the Atrium (heart), atrial chambers of the heart. It often begins as short periods ...
,
atrial flutter Atrial flutter (AFL) is a common abnormal heart rhythm that starts in the atrial chambers of the heart. When it first occurs, it is usually associated with a fast heart rate and is classified as a type of supraventricular tachycardia (SVT). ...
and sometimes
heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome caused by an impairment in the heart's ability to Cardiac cycle, fill with and pump blood. Although symptoms vary based on which side of the heart is affected, HF ...
.


Polyphenols

Polyphenol Polyphenols () are a large family of naturally occurring phenols. They are abundant in plants and structurally diverse. Polyphenols include phenolic acids, flavonoids, tannic acid, and ellagitannin, some of which have been used historically as ...
s of several classes are widespread in plants, having diverse roles in defenses against plant diseases and predators. They include hormone-mimicking
phytoestrogen A phytoestrogen is a plant-derived xenoestrogen (a type of estrogen produced by organisms other than humans) not generated within the endocrine system, but consumed by eating plants or manufactured foods. Also called a "dietary estrogen", it ...
s and astringent
tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...
s. Plants containing phytoestrogens have been administered for centuries for gynecological disorders, such as fertility, menstrual, and menopausal problems. Among these plants are '' Pueraria mirifica'',
kudzu Kudzu (), also called Japanese arrowroot or Chinese arrowroot, is a group of climbing, coiling, and trailing deciduous perennial vines native to much of East Asia, Southeast Asia, and some Pacific islands. It is invasive species, invasive in ...
,
angelica ''Angelica'' is a genus of about 90 species of tall Biennial plant, biennial and Perennial plant, perennial herbaceous, herbs in the family Apiaceae, native to temperate and subarctic regions of the Northern Hemisphere, reaching as far north as ...
,
fennel Fennel (''Foeniculum vulgare'') is a flowering plant species in the carrot family. It is a hardy, perennial herb with yellow flowers and feathery leaves. It is indigenous to the shores of the Mediterranean but has become widely naturalized ...
, and
anise Anise (; '), also called aniseed or rarely anix, is a flowering plant in the family Apiaceae native to the eastern Mediterranean region and Southwest Asia. The flavor and aroma of its seeds have similarities with some other spices and herbs, ...
. Many polyphenolic extracts, such as from grape seeds,
olive The olive, botanical name ''Olea europaea'' ("European olive"), is a species of Subtropics, subtropical evergreen tree in the Family (biology), family Oleaceae. Originating in Anatolia, Asia Minor, it is abundant throughout the Mediterranean ...
s or maritime pine bark, are sold as
dietary supplement A dietary supplement is a manufactured product intended to supplement a person's diet by taking a pill (pharmacy), pill, capsule (pharmacy), capsule, tablet (pharmacy), tablet, powder, or liquid. A supplement can provide nutrients eithe ...
s and
cosmetics Cosmetics are substances that are intended for application to the body for cleansing, beautifying, promoting attractiveness, or altering appearance. They are mixtures of chemical compounds derived from either Natural product, natural source ...
without proof or legal
health claim A health claim on a food label and in food marketing is a claim by a manufacturer of food products that their food will reduce the risk of developing a disease or condition. For example, it is claimed by the manufacturers of oat cereals that oa ...
s for medicinal effects. In Ayurveda, the astringent rind of the
pomegranate The pomegranate (''Punica granatum'') is a fruit-bearing deciduous shrub in the family Lythraceae, subfamily Punica, Punicoideae, that grows between tall. Rich in symbolic and mythological associations in many cultures, it is thought to have o ...
, containing polyphenols called
punicalagin Punicalagin (''Pyuni-cala-jen'') is an ellagitannin, a type of phenolic compound. It is found as alpha and beta isomers in pomegranates (''Punica granatum''), '' Terminalia catappa'', '' Terminalia myriocarpa'', and in '' Combretum molle'', the ...
s, is used as a medicine, with no scientific proof of efficacy. File:Angelica sylvestris 3.jpg,
Angelica ''Angelica'' is a genus of about 90 species of tall Biennial plant, biennial and Perennial plant, perennial herbaceous, herbs in the family Apiaceae, native to temperate and subarctic regions of the Northern Hemisphere, reaching as far north as ...
, containing
phytoestrogen A phytoestrogen is a plant-derived xenoestrogen (a type of estrogen produced by organisms other than humans) not generated within the endocrine system, but consumed by eating plants or manufactured foods. Also called a "dietary estrogen", it ...
s, has long been used for gynaecological disorders. File:Phytoestrogens2.png,
Polyphenol Polyphenols () are a large family of naturally occurring phenols. They are abundant in plants and structurally diverse. Polyphenols include phenolic acids, flavonoids, tannic acid, and ellagitannin, some of which have been used historically as ...
s include
phytoestrogen A phytoestrogen is a plant-derived xenoestrogen (a type of estrogen produced by organisms other than humans) not generated within the endocrine system, but consumed by eating plants or manufactured foods. Also called a "dietary estrogen", it ...
s (top and middle), mimics of animal
estrogen Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three ...
(bottom).


Terpenes

Terpenes Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predomi ...
and terpenoids of many kinds are found in a variety of medicinal plants, and in
resin A resin is a solid or highly viscous liquid that can be converted into a polymer. Resins may be biological or synthetic in origin, but are typically harvested from plants. Resins are mixtures of organic compounds, predominantly terpenes. Commo ...
ous plants such as the
conifers Conifers () are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All e ...
. They are strongly aromatic and serve to repel herbivores. Their scent makes them useful in essential oils, whether for
perfume Perfume (, ) is a mixture of fragrance, fragrant essential oils or aroma compounds (fragrances), Fixative (perfumery), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agre ...
s such as
rose A rose is either a woody perennial plant, perennial flowering plant of the genus ''Rosa'' (), in the family Rosaceae (), or the flower it bears. There are over three hundred Rose species, species and Garden roses, tens of thousands of cultivar ...
and
lavender ''Lavandula'' (common name lavender) is a genus of 47 known species of perennial flowering plants in the sage family, Lamiaceae. It is native plant, native to the Old World, primarily found across the drier, warmer regions of the Mediterranean ...
, or for
aromatherapy Aromatherapy is a practice based on the use of aromatic materials, including essential oils and other aroma compounds, with claims for improving psychological well-being. It is used as a complementary therapy or as a form of alternative medic ...
. Some have medicinal uses: for example,
thymol Thymol (also known as 2-isopropyl-5-methylphenol, IPMP), , is a toxic monoterpenoid phenol derivative of ''p''-Cymene, isomeric with carvacrol. It occurs naturally in the oil of thyme, and it is extracted from ''Thymus vulgaris'' (common thy ...
is an antiseptic and was once used as a vermifuge (anti-worm medicine). File:Thymian.jpg, The
essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the ...
of common thyme (''Thymus vulgaris''), contains the
monoterpene Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen func ...
thymol Thymol (also known as 2-isopropyl-5-methylphenol, IPMP), , is a toxic monoterpenoid phenol derivative of ''p''-Cymene, isomeric with carvacrol. It occurs naturally in the oil of thyme, and it is extracted from ''Thymus vulgaris'' (common thy ...
, an
antiseptic An antiseptic ( and ) is an antimicrobial substance or compound that is applied to living tissue to reduce the possibility of sepsis, infection, or putrefaction. Antiseptics are generally distinguished from ''antibiotics'' by the latter's abil ...
and
antifungal An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as ...
. File:Thymol2.svg, Thymol is one of many
terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predomi ...
s found in plants.


In practice


Cultivation

Medicinal plants demand intensive management. Different species each require their own distinct conditions of cultivation. The
World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...
recommends the use of
rotation Rotation or rotational/rotary motion is the circular movement of an object around a central line, known as an ''axis of rotation''. A plane figure can rotate in either a clockwise or counterclockwise sense around a perpendicular axis intersect ...
to minimise problems with pests and plant diseases. Cultivation may be traditional or may make use of conservation agriculture practices to maintain organic matter in the soil and to conserve water, for example with no-till farming systems. In many medicinal and aromatic plants, plant characteristics vary widely with soil type and cropping strategy, so care is required to obtain satisfactory yields.


Preparation

Medicinal plants are often tough and fibrous, requiring some form of preparation to make them convenient to administer. According to the Institute for Traditional Medicine, common methods for the preparation of herbal medicines include decoction, powdering, and extraction with alcohol, in each case yielding a mixture of substances. Decoction involves crushing and then boiling the plant material in water to produce a liquid extract that can be taken orally or applied topically. Powdering involves drying the plant material and then crushing it to yield a powder that can be compressed into tablets. Alcohol extraction involves soaking the plant material in cold wine or distilled spirit to form a
tincture A tincture is typically an extract of plant or animal material dissolved in ethanol (ethyl alcohol). Solvent concentrations of 25–60% are common, but may run as high as 90%.Groot Handboek Geneeskrachtige Planten by Geert Verhelst In chemistr ...
. Traditional
poultice A poultice or cataplasm, also called a fomentation, is a soft moist mass, often heated and medicated, that is applied to the skin to reduce inflammation, soothe pain, promote healing, or otherwise treat wounds or ailments. Soft materials like cer ...
s were made by boiling medicinal plants, wrapping them in a cloth, and applying the resulting parcel externally to the affected part of the body. When modern medicine has identified a drug in a medicinal plant, commercial quantities of the drug may either be synthesised or extracted from plant material, yielding a pure chemical. Extraction can be practical when the compound in question is complex.


Usage

Plant medicines are in wide use around the world. In most of the developing world, especially in rural areas, local
traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) refers to the knowledge, skills, and practices rooted in the cultural beliefs of various societies, especially Indigenous groups, used for maintaining health and treatin ...
, including herbalism, is the only source of health care for people, while in the
developed world A developed country, or advanced country, is a sovereign state that has a high quality of life, developed economy, and advanced technological infrastructure relative to other less industrialized nations. Most commonly, the criteria for eval ...
,
alternative medicine Alternative medicine refers to practices that aim to achieve the healing effects of conventional medicine, but that typically lack biological plausibility, testability, repeatability, or supporting evidence of effectiveness. Such practices are ...
including use of
dietary supplements A dietary supplement is a manufactured product intended to supplement a person's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources, or that are synthetic ...
is marketed aggressively using the claims of traditional medicine. As of 2015, most products made from medicinal plants had not been tested for their safety and efficacy, and products that were marketed in developed economies and provided in the undeveloped world by traditional healers were of uneven quality, sometimes containing dangerous contaminants.
Traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medicine, alternative medical practice drawn from traditional medicine in China. A large share of its claims are pseudoscientific, with the majority of treatments having no robust evidence ...
makes use of a wide variety of plants, among other materials and techniques. Researchers from
Kew Gardens Kew Gardens is a botanical garden, botanic garden in southwest London that houses the "largest and most diverse botany, botanical and mycology, mycological collections in the world". Founded in 1759, from the exotic garden at Kew Park, its li ...
found 104 species used for
diabetes Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...
in Central America, of which seven had been identified in at least three separate studies. The
Yanomami The Yanomami, also spelled Yąnomamö or Yanomama, are a group of approximately 35,000 indigenous people of the Americas, indigenous people who live in some 200–250 villages in the Amazon rainforest on the border between Venezuela and Brazil. ...
of the Brazilian Amazon, assisted by researchers, have described 101 plant species used for traditional medicines. Drugs derived from plants including opiates, cocaine and cannabis have both medical and recreational uses. Different countries have at various times made use of illegal drugs, partly on the basis of the risks involved in taking
psychoactive drug A psychoactive drug, psychopharmaceutical, mind-altering drug, consciousness-altering drug, psychoactive substance, or psychotropic substance is a chemical substance that alters psychological functioning by modulating central nervous system acti ...
s.


Effectiveness

Plant medicines have often not been tested systematically, but have come into use informally over the centuries. By 2007, clinical trials had demonstrated potentially useful activity in nearly 16% of herbal extracts; there was limited in vitro or in vivo evidence for roughly half the extracts; there was only phytochemical evidence for around 20%; 0.5% were allergenic or toxic; and some 12% had basically never been studied scientifically. Cancer Research UK caution that there is no reliable evidence for the effectiveness of herbal remedies for cancer. A 2012
phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
study built a family tree down to
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
level using 20,000 species to compare the medicinal plants of three regions, Nepal, New Zealand and the Cape of South Africa. It discovered that the species used traditionally to treat the same types of condition belonged to the same groups of plants in all three regions, giving a "strong phylogenetic signal". Since many plants that yield pharmaceutical drugs belong to just these groups, and the groups were independently used in three different world regions, the results were taken to mean 1) that these plant groups do have potential for medicinal efficacy, 2) that undefined pharmacological activity is associated with use in traditional medicine, and 3) that the use of a phylogenetic groups for possible plant medicines in one region may predict their use in the other regions.


Regulation

The World Health Organization (WHO) has been coordinating a network called the International Regulatory Cooperation for Herbal Medicines to try to improve the quality of medical products made from medicinal plants and the claims made for them. In 2015, only around 20% of countries had well-functioning regulatory agencies, while 30% had none, and around half had limited regulatory capacity. In India, where
Ayurveda Ayurveda (; ) is an alternative medicine system with historical roots in the Indian subcontinent. It is heavily practised throughout India and Nepal, where as much as 80% of the population report using ayurveda. The theory and practice of ayur ...
has been practised for centuries, herbal remedies are the responsibility of a government department, AYUSH, under the Ministry of Health & Family Welfare. WHO has set out a strategy for traditional medicines with four objectives: to integrate them as policy into national healthcare systems; to provide knowledge and guidance on their safety, efficacy, and quality; to increase their availability and affordability; and to promote their rational, therapeutically sound usage. WHO notes in the strategy that countries are experiencing seven challenges to such implementation, namely in developing and enforcing policy; in integration; in safety and quality, especially in assessment of products and qualification of practitioners; in controlling advertising; in research and development; in education and training; and in the sharing of information.


Drug discovery

The
pharmaceutical industry The pharmaceutical industry is a medical industry that discovers, develops, produces, and markets pharmaceutical goods such as medications and medical devices. Medications are then administered to (or self-administered by) patients for curing ...
has roots in the
apothecary ''Apothecary'' () is an Early Modern English, archaic English term for a medicine, medical professional who formulates and dispenses ''materia medica'' (medicine) to physicians, surgeons and patients. The modern terms ''pharmacist'' and, in Brit ...
shops of Europe in the 1800s, where pharmacists provided local traditional medicines to customers, which included extracts like morphine, quinine, and strychnine. Therapeutically important drugs like
camptothecin Camptothecin (CPT) is a topoisomerase inhibitor. It was discovered in 1966 by M. E. Wall and M. C. Wani in systematic screening of natural products for anticancer drugs. It was isolated from the Bark (botany), bark of ''Camptotheca acuminata'' ( ...
(from '' Camptotheca acuminata'', used in traditional Chinese medicine) and
taxol Paclitaxel, sold under the brand name Taxol among others, is a chemotherapy medication used to treat ovarian cancer, esophageal cancer, breast cancer, lung cancer, Kaposi's sarcoma, cervical cancer, and pancreatic cancer. It is administered by ...
(from the Pacific yew, '' Taxus brevifolia'') were derived from medicinal plants. The
Vinca alkaloids ''Vinca'' alkaloids are a set of anti-mitotic and anti-microtubule alkaloid agents originally derived from the periwinkle plant '' Catharanthus roseus'' (basionym ''Vinca rosea'') and other ''vinca'' plants. They block beta-tubulin polymeriza ...
vincristine Vincristine, also known as leurocristine and sold under the brand name Oncovin among others, is a chemotherapy medication used to treat a number of types of cancer. This includes acute lymphocytic leukemia, acute myeloid leukemia, Hodgkin lym ...
and
vinblastine Vinblastine, sold under the brand name Velban among others, is a chemotherapy medication, typically used with other medications, to treat a number of types of cancer. This includes Hodgkin's lymphoma, non-small-cell lung cancer, bladder canc ...
, used as anti-cancer drugs, were discovered in the 1950s from the Madagascar periwinkle, '' Catharanthus roseus''. Hundreds of compounds have been identified using
ethnobotany Ethnobotany is an interdisciplinary field at the interface of natural and social sciences that studies the relationships between humans and plants. It focuses on traditional knowledge of how plants are used, managed, and perceived in human socie ...
, investigating plants used by indigenous peoples for possible medical applications. Some important phytochemicals, including curcumin,
epigallocatechin gallate Epigallocatechin gallate (EGCG), also known as epigallocatechin-3-gallate, is the ester of epigallocatechin and gallic acid, and is a type of catechin. EGCG – the most abundant catechin in tea – is a polyphenol under basic research for it ...
,
genistein Genistein (C15H10O5) is a plant-derived, aglycone isoflavone. Genistein has the highest content of all isoflavones in soybeans and soy products, such as tempeh. As a type of phytoestrogen, genistein has estrogenic activity in vitro; consequ ...
and
resveratrol Resveratrol (3,5,4′-trihydroxy-''trans''-stilbene) is a stilbenoid, a type of natural phenol or polyphenol and a phytoalexin produced by several plants in response to injury or when the plant is under attack by pathogens, such as bacterium, ba ...
are pan-assay interference compounds, meaning that ''
in vitro ''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...
'' studies of their activity often provide unreliable data. As a result, phytochemicals have frequently proven unsuitable as the lead substances in
drug discovery In the fields of medicine, biotechnology, and pharmacology, drug discovery is the process by which new candidate medications are discovered. Historically, drugs were discovered by identifying the active ingredient from traditional remedies or ...
. In the United States over the period 1999 to 2012, despite several hundred applications for new drug status, only two botanical drug candidates had sufficient evidence of medicinal value to be approved by the
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...
. The pharmaceutical industry has remained interested in mining traditional uses of medicinal plants in its drug discovery efforts. Of the 1073 small-molecule drugs approved in the period 1981 to 2010, over half were either directly derived from or inspired by natural substances. Among cancer treatments, of 185 small-molecule drugs approved in the period from 1981 to 2019, 65% were derived from or inspired by natural substances.


Safety

Plant medicines can cause adverse effects and even death, whether by side-effects of their active substances, by adulteration or contamination, by overdose, or by inappropriate prescription. Many such effects are known, while others remain to be explored scientifically. There is no reason to presume that because a product comes from nature it must be safe: the existence of powerful natural poisons like atropine and nicotine shows this to be untrue. Further, the high standards applied to conventional medicines do not always apply to plant medicines, and dose can vary widely depending on the growth conditions of plants: older plants may be much more toxic than young ones, for instance. Plant extracts may interact with conventional drugs, both because they may provide an increased dose of similar compounds, and because some phytochemicals interfere with the body's systems that metabolise drugs in the liver including the
cytochrome P450 Cytochromes P450 (P450s or CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that mostly, but not exclusively, function as monooxygenases. However, they are not omnipresent; for examp ...
system, making the drugs last longer in the body and have a cumulative effect. Plant medicines can be dangerous during pregnancy. Since plants may contain many different substances, plant extracts may have complex effects on the human body.


Quality, advertising, and labelling

Herbal medicine and dietary supplement products have been criticized as not having sufficient standards or scientific evidence to confirm their contents, safety, and presumed efficacy. Companies often make false claims about their herbal products promising health benefits that aren't backed by evidence to generate more sales. The market for dietary supplements and nutraceuticals grew by 5% during the COVID-19 pandemic, which led to the United States taking action to stop the deceptive marketing of herbal products to combat the virus.


Threats

Where medicinal plants are harvested from the wild rather than cultivated, they are subject to both general and specific threats. General threats include
climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
and
habitat loss Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...
to development and agriculture. A specific threat is over-collection to meet rising demand for medicines. A case in point was the pressure on wild populations of the Pacific yew soon after news of taxol's effectiveness became public. The threat from over-collection could be addressed by cultivation of some medicinal plants, or by a system of certification to make wild harvesting sustainable. A report in 2020 by the Royal Botanic Gardens, Kew identifies 723 medicinal plants as being at risk of extinction, caused partly by over-collection.


See also

* Australian Phytochemical Survey * Ethnomedicine * European Directive on Traditional Herbal Medicinal Products *
Plant Resources of Tropical Africa Plants are the eukaryotes that form the kingdom Plantae; they are predominantly photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars f ...


Notes


References

{{Authority control Plants and humans