Chemical and physical properties of vitamin K Domina Petric, MD

Essential features of the chemical structure: Derivative of 2-methyl-1,4-naphthoquinone. Ring structure has a hydrophobic constituent at the 3-position and can be alkylated with an isoprenoid side chain. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Chemical structures of the vitamin K group: Phylloquinones Menaquinones Menadione Sigmaaldrich.com November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Vitamin K nomenclature Vitamin K is the generic descriptor for 2-methyl-1,4-naphthoquinone and all of its derivatives exhibiting qualitatively the biological (antihemorrhagic) activity of phylloquinone. Naturally occurring forms of the vitamin have an unsaturated isoprenoid side chain at C-3 of the naphthoquinone nucleus. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Vitamin K nomenclature The phylloquinone group includes forms with phytyl side chains and side chains that are further alkylated, thus consisting of several saturated isoprenoid units. The vitamers of this group have only one double bond in their side chains: on the proximal isoprene unit. These vitamers are synthesized by green plants. They are properly referred to as phylloquinones and are abbreviated as K. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Vitamin K nomenclature The menaquinone group also includes vitamers with side chains consisting of variable numbers of isoprenoid units. Each isoprene unit has a double bond. These vitamers are synthesized by bacteria. They are abbreviated as MK13 and were formerly referred to as vitamin K2. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Vitamin K nomenclature The compound 2-methyl-1,4-naphthoquinone (without a side chain) is called menadione. It does not exist naturally, but has biological activity by virtue of the fact that animals can alkylate it to produce such metabolites as MK-4. Menadione is made in several forms: menadione sodium bisulfite complex, menadione dimethylpyrimidinol bisulfite. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Vitamin K nomenclature The abbreviations K-n and MK-n are used for the phylloquinones and menaquinones to indicate specific vitamers with side chains consisting of n isoprenoid units. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Chemical and physical properties of vitamin K Phylloquinone (K1) is a yellow oil at room temperature, but the other vitamers K are yellow crystals. The vitamers K, MK, and most forms of menadione are insoluble in water, slightly soluble in ethanol, and readily soluble in ether, chloroform, fats and oils. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Chemical and physical properties of vitamin K The vitamers K are sensitive to light and alkali, but are relatively stable to heat and oxidizing environments. Their oxidation proceeds to produce the 2,3-epoxide form. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Vitamin K biopotency The biopotency of vitamers K depends on both the nature and length of their isoprenoid side chains. The menaquinones (K-2) tend to have greater biopotencies than the corresponding phylloquinone analogs. Members of each series with four or five isoprenoid side chains are the most biopotent. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Literature Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008. November 20, 2018