Withania Somnifera

''Withania somnifera'', known commonly as ashwagandha, is an evergreen shrub in the Solanaceae family that is native to the Middle East and North Africa, other African regions, southern Europe, and Indian subcontinent. Several other species in the genus '' Withania'' are morphologically similar. Common names include Indian ginseng and winter cherry.

''W. somnifera'' is a short shrub 35–75 cm tall with tomentose branches, dull green elliptic leaves up to 10–12 cm long, small green bell-shaped flowers, and orange-red ripe fruit. The Latin species name ''somnifera'' means “ sleep-inducing,” while the name ashwagandha combines the Sanskrit words for “horse” and “smell,” referring to the root’s strong horse-like odor. It is cultivated mainly in dry regions of India and nearby countries like Nepal, Sri Lanka, China, and Yemen, preferring dry, stony soil with sun to partial shade, and is propagated from seeds in early spring or greenwood cuttings later. It is affected by various pests and diseases in India, which can damage plant health and reduce its secondary metabolite content.

The plant, particularly its root powder, has been used for centuries in traditional Indian medicine. ''W. somnifera'' is commonly sold as a dietary supplement containing root or leaf powder or extracts. It is undergoing research for potential effects on stress, anxiety, and sleep, but current clinical evidence is insufficient to confirm its safety or efficacy. The primary phytochemicals in ''W. somnifera'' are withanolides—structurally similar to ginsenosides in '' Panax ginseng''—along with alkaloids and sitoindosides, leading to its nickname “Indian ginseng.”

''W. somnifera'' is generally well tolerated for up to about 3 months with mostly mild side effects. It should be avoided during pregnancy or in people with hormone-sensitive conditions. It has been linked to rare cases of liver injury, particularly in people with preexisting liver conditions.

Description

This species is a short shrub growing tall. Tomentose branches extend radially from a central stem. Leaves are dull green, elliptic, and usually up to long. The flowers are small, green, and bell-shaped. The ripe fruit is orange-red.

Etymology

The Latin species name means "sleep-inducing". The name ''ashwagandha'' is a combination of the Sanskrit words ', meaning "horse", and ', meaning "smell", reflecting that the root has a strong, horse-like odor.

Cultivation

''W. somnifera'' is cultivated in many of the drier regions of India. It is also found in Nepal, Sri Lanka, China, and Yemen. It prefers dry, stony soil with sun to partial shade. It can be propagated from seeds in the early spring or from greenwood cuttings in the later spring.

Diseases and pests

''W. somnifera'' is prone to several pests and diseases. Leaf-spot disease caused by ''Alternaria alternata'' is the most prevalent disease, which occurs in a severe form in Punjab, Haryana, and Himachal Pradesh. Leaf-spot disease reduces the concentration of its secondary metabolites. The leaves are also prone to '' Alternaria dianthicola'' in India.

A treehopper (''Oxyrachis tarandus'') feeds on the apical portions of the stem, making them rough and woody in appearance and brown in colour.

The carmine red spider mite (''Tetranychus urticae'') is the most prevalent pest of the plant in India. In recent years, this plant has been serving as a new reservoir host for an invasive mealybug species '' Phenacoccus solenopsis''.

Phytochemistry

The main phytochemical constituents of ''W. somnifera'' are withanolides, a group of triterpene lactones that include withaferin A, alkaloids, steroidal lactones, tropine, and cuscohygrine. Forty withanolides, twelve alkaloids, and various sitoindosides have been isolated from this plant species. As these withanolides are structurally similar to the ginsenosides of '' Panax ginseng'', ''W. somnifera'' is commonly referred to as "Indian ginseng".

Traditional medicine and dietary supplements

The plant, particularly its root powder, has been used for centuries in traditional Indian medicine. ''W. somnifera'' is commonly sold as a dietary supplement containing root or leaf powder or extracts. It is undergoing research for potential effects on stress, anxiety, and sleep, but current clinical evidence is insufficient to confirm its safety or efficacy.

Stress and anxiety

At oral doses of 300 to 600 mg per day over a three month period, ashwagandha root extract may be useful in treating generalized anxiety disorder, although the evidence for efficacy is tentative and the treatment may cause nausea and diarrhea.

Sleep

There is limited evidence that ''W. somnifera'' extract, especially at higher doses and over longer durations, may modestly improve sleep quality and related outcomes, with more noticeable effects in people with insomnia. A 2021 review concluded that ''W. somnifera'' extract modestly improves sleep quality and quantity in adults, especially those with insomnia, and may reduce anxiety and enhance alertness.

Adverse effects

''W. somnifera'' may cause adverse effects if taken alone or together with prescription drugs. The most common side effects include diarrhea, headache, sedation, and nausea. Ashwagandha may increase testosterone levels, which could adversely interact with cancer medications.

''W. somnifera'' can cause hepatotoxicity, and its use as a supplement has been linked to herb-induced liver injury, particularly in people with preexisting liver conditions.

Use of ''W. somnifera'' is not recommended during pregnancy or in people with hormone-sensitive prostate cancer.

Gallery

File:Withania somnifera MHNT.BOT.2012.10.13.jpg, Fruits
File:Withaniae2.JPG, Druggist's jar containing dried roots of ''Withania somnifera''
File:Ashwagandha Roots.jpg, Dried graded roots of ''Withania somnifera''

References

External links

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Flora of Lebanon
Flora of Nepal
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