Phytomenadione, also known as vitamin K₁ or phylloquinone, is a

vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrie ...

found in food and used as a

dietary supplement A dietary supplement is a manufactured product intended to supplement one'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 in order ...

. It is on the World Health Organization's List of Essential Medicines. As a supplement it is used to treat certain

bleeding disorders Coagulopathy (also called a bleeding disorder) is a condition in which the blood's ability to coagulate (form clots) is impaired. This condition can cause a tendency toward prolonged or excessive bleeding (bleeding diathesis), which may occur spo ...

. This includes warfarin overdose, vitamin K deficiency, and obstructive jaundice. It is also recommended to prevent and treat vitamin K deficiency bleeding in infants. Use is typically recommended by mouth, intramuscular injection or injection under the skin. When given by injection benefits are seen within two hours. Many countries in the world choose intramuscular injections in newborn to keep them safe from severe bleeding (VKDB). It is considered a safe treatment and saves many children from death and severe neurologic deficit every year. Side effects when given by injection may include pain at the site of injection. Severe

allergic reactions Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derm ...

may occur when it is injected into a vein or muscle, but this has mainly happened when large doses of a certain type of supplement containing

castor oil Castor oil is a vegetable oil pressed from castor beans. It is a colourless or pale yellow liquid with a distinct taste and odor. Its boiling point is and its density is 0.961 g/cm3. It includes a mixture of triglycerides in which about ...

were given intravenously. Use during pregnancy is considered safe, use is also likely okay during

breastfeeding Breastfeeding, or nursing, is the process by which human breast milk is fed to a child. Breast milk may be from the breast, or may be expressed by hand or pumped and fed to the infant. The World Health Organization (WHO) recommends that bre ...

. It works by supplying a required component for making a number of

blood clotting factors Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism o ...

. Found sources include green vegetables, vegetable oil, and some fruit. Phytomenadione was first isolated in 1939. In 1943

Edward Doisy Edward Adelbert Doisy (November 13, 1893 – October 23, 1986) was an American biochemist. He received the Nobel Prize in Physiology or Medicine in 1943 with Henrik Dam for their discovery of vitamin K (K from "Koagulations-Vitamin" in German) an ...

and

Henrik Dam Carl Peter Henrik Dam ( da, Carl Peter Henrik Dam), (21 February 1895 – 17 April 1976) was a Danish biochemist and physiologist. He was awarded the Nobel Prize in Medicine in 1943 for joint work with Edward Doisy in discovering vitamin K a ...

were given a

Nobel Prize The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...

for its discovery.

Terminology

Phytomenadione is often also called phylloquinone, vitamin K, or phytonadione. A

stereoisomer In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in ...

of phylloquinone is called vitamin k₁ (note the difference in capitalization).

Chemistry

Vitamin K is a fat-soluble vitamin that is stable in air and moisture but decomposes in sunlight. It is a polycyclic

aromatic In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double b ...

, based on 2-

methyl In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in ...

- 1,4-naphthoquinone, with a 3- phytyl

substituent A substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety in the resultant (new) molecule. (In organic chemistry and biochemistry, the terms ''substituent'' and ''functional group'', as well as '' side ...

. It is found naturally in a wide variety of green plants, particularly in leaves, since it functions as an electron acceptor during

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...

, forming part of the electron transport chain of

photosystem I Photosystem I (PSI, or plastocyanin–ferredoxin oxidoreductase) is one of two photosystems in the photosynthetic light reactions of algae, plants, and cyanobacteria. Photosystem I is an integral membrane protein complex that us ...

Biological function

The best-known function of vitamin K in animals is as a cofactor in the formation of

coagulation factor Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism o ...

s II ( prothrombin), VII, IX, and X by the liver. It is also required for the formation of anticoagulant factors protein C and S. It is commonly used to treat

warfarin Warfarin, sold under the brand name Coumadin among others, is a medication that is used as an anticoagulant (blood thinner). It is commonly used to prevent blood clots such as deep vein thrombosis and pulmonary embolism, and to prevent st ...

toxicity, and as an antidote for coumatetralyl. Vitamin K is required for bone protein formation.

Biosynthesis

Vitamin K₁ is synthesized from chorismate, a compound produced from shikimate via the shikimate pathway. The conversion of chorismate to vitamin K₁ comprises a series of nine steps: # Chorismate is isomerized to isochorismate by isochorismate synthase, or MenF (menaquinone enzyme). # Addition of 2-oxoglutarate to isochorismate by PHYLLO, a multifunctional protein comprising three different enzymatic activities (MenD, H, and C). # Elimination of pyruvate by PHYLLO. # Aromatization to yield o-succinyl benzoate by PHYLLO. # O-succinylbenzoate activation to corresponding CoA ester by MenE. # Naphthoate ring formation by naphthoate synthase (MenB/NS). # Thiolytic release of CoA by a thioesterase (MenH). # Attachment of phytol chain to the naphthoate ring (MenA/ABC4). #

Methylation In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These ...

of the precursor at position 3 (MenG). Vitamin K₁ is required for plant

, where it participates in the

Photosystem I Photosystem I (PSI, or plastocyanin–ferredoxin oxidoreductase) is one of two photosystems in the photosynthetic light reactions of algae, plants, and cyanobacteria. Photosystem I is an integral membrane protein complex that us ...

electron transport chain An electron transport chain (ETC) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples ...

. As a result, it is rich in leaves.

References

External links