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. It is on the

World Health Organization's List of Essential Medicines The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health s ...

. As a supplement it is used to treat certain bleeding disorders. This includes

warfarin overdose 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 strok ...

vitamin K deficiency Vitamin K deficiency results from insufficient dietary vitamin K1 or vitamin K2 or both. Signs and symptoms Symptoms include bruising, petechiae, hematomas, oozing of blood at surgical or puncture sites, stomach pains; risk of massive uncontro ...

, and

obstructive jaundice Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme me ...

. It is also recommended to prevent and treat

vitamin K deficiency bleeding Vitamin K deficiency bleeding (VKDB) of the newborn, previously known as haemorrhagic disease of the newborn, is a rare form of bleeding disorder that affects newborns and young infants due to low stores of vitamin K at birth. It commonly presents ...

in infants. Use is typically recommended by mouth, intramuscular injection or

injection under the skin Subcutaneous administration is the insertion of medications beneath the skin either by injection or infusion. A subcutaneous injection is administered as a bolus into the subcutis, the layer of skin directly below the dermis and epidermis, col ...

. 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 br ...

. It works by supplying a required component for making a number of blood clotting factors. Found sources include

green vegetables Leaf vegetables, also called leafy greens, pot herbs, vegetable greens, or simply greens, are plant leaves eaten as a vegetable, sometimes accompanied by tender petioles and shoots. Leaf vegetables eaten raw in a salad can be called salad gr ...

, vegetable oil, and some fruit. Phytomenadione was first isolated in 1939. In 1943 Edward Doisy 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, based on 2- methyl- 1,4-naphthoquinone, with a 3-

phytyl Phytane is the isoprenoid alkane formed when phytol, a constituent of chlorophyll, loses its hydroxyl group. When phytol loses one carbon atom, it yields pristane. Other sources of phytane and pristane have also been proposed than phytol. Pris ...

substituent. 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 i ...

, 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 Thrombin (, ''fibrinogenase'', ''thrombase'', ''thrombofort'', ''topical'', ''thrombin-C'', ''tropostasin'', ''activated blood-coagulation factor II'', ''blood-coagulation factor IIa'', ''factor IIa'', ''E thrombin'', ''beta-thrombin'', ''gamma- ...

), 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 Coumatetralyl is an anticoagulant of the 4-hydroxycoumarin vitamin K antagonist type used as a rodenticide. Common applications Coumatetralyl is commonly used with grains and other cereals as a rodent poison in conjunction with a tracking po ...

. 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 In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Is ...

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 Aromatization is a chemical reaction in which an aromatic system is formed from a single nonaromatic precursor. Typically aromatization is achieved by dehydrogenation of existing cyclic compounds, illustrated by the conversion of cyclohexane int ...

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 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. As a result, it is rich in leaves.

References

External links