Menaquinone menadione

The K vitamins include vitamin Ki, phylloquinone or phytonadione, and vitamin K2 which is a group of compounds, the menaquinones. Menadione, vitamin K3, is a precursor of menaquinone-4. Vitamin K is present in alfalfa and fish livers. Other dietary sources include green vegetables, soybean oil and eggs. A normal diet together with the bacterial synthesis of vitamin K in the gut are usually sufficient to prevent deficiencies in healthy adults. 

Menaquinone, menadione see vitamin K]. p-Menthadienes. Doubly unsaturated, monocyclic monoterpenes derived from p-menthane. C,oH 6, Mr 136.23, liquids, sensitive to light, air, and heat. Occurrence p-M. are widely distributed in nature. The table (see below) lists those plants from which laiger amounts of p-M. can be isolated from the essential oils. /S-Terpinene and (-)-j8-phellandrene occur in very small amounts only. 

Figure 1 Chemical structures of phylloquinone, menaquinones, menadione, warfarin, and dicumarol.

Figure 45-7. The vitamin K vitamers. Menadiol (or menadione) and menadiol diacetate are synthetic compounds that are converted to menaquinone in the liver and have vitamin Kactivity.

Dimerization chlorpromazine dithranol protriptyline vanillin ethinyloestradiol folic acid frusemide menadione menaquinone-1... 

Hypoprothrombinemia may occur in malabsorption syndromes and also the use of broad-spectrum antibiotics may produce a hypoprothrombinemia that responds readily to small doses of vitamin K. In premature infants and in infants with hemorrhagic disease of the newborn the use of vitamin K may be indicated. However, the main indication for the use of vitamin K is to antagonize the anticoagulant activity of coumarins. Oral absorption of phytonadione and the menaquinones is by the lymph while menadione and its water-soluble derivatives are absorbed directly. The absorption of phytonadione is energy-dependent and saturable. Intravenous administration of phytonadione has produced flushing, dyspnea, chest pains, and cardiovascular collapse. 

Vitamin K activity is associated with several quinones, including phylloquinone (vitamin Kj), menadione (vitamin K3), and a variety of menaquinones (vitamin K2). These quinones promote the synthesis of proteins that are involved in the coagulation of blood. These proteins include prothrombin, factor VII (proconvertin), factor IX (plasma thromboplastin), and factor X (Stuart factor). A detailed discussion of blood coagulation is found in Chapter 22. The vitamin K quinones are obtained from three major sources. Vitamin K is present in vari-... 

The structure of vitamin K is characterized by methylnaphthoquinone rings with a side chain at position 3. It exists naturally in two forms phylloquinone (vitamin Kt 6.13) occurs only in plants, while menaquinones (vitamin K2 6.14) are a family of compounds with a side chain consisting of between 1 and 14 isoprene units. Menaquinones are synthesized only by bacteria (which inhabit the human gastrointestinal tract and thus provide some of the vitamin K required by the body). Menadione (vitamin K3 6.15) is a synthetic compound with vitamin K activity. Unlike Kj and K2, menadione is water soluble and is not active until it is alkylated in vivo. 

Vitamin K Menadione Menaquinone Phylloquinone Menadione Menequinone Phylloquinon y-Carboxylation of glutamate residue in clotting and other proteins... 

Vitamin K (menadione, menaquinone, and phyloquinone) are responsible for they-car-boxylation of glutamate residues in clotting factors and other proteins. A deficiency of vitamin K is seen in newborns but is rare in adults it causes bleeding. The vitamin has little toxicity. 

Another important family of quinones, related in structure to those already discussed, are the vitamins K (Fig. 15-24, Box 15-F). These occur naturally as two families. The vitamins K, (phylloquinones) have only one double bond in the side chain and that is in the prenyl unit closest to the ring. This suggests again the possibility of chromanol formation. In the vitamin K2 (menaquinone) series, a double bond is present in each of the prenyl units. A synthetic compound menadione completely lacks the polyprenyl side chain and bears a hydrogen in the corresponding position on the ring. Nevertheless, menadione serves as a synthetic vitamin K, apparently because it can be converted in the body to forms containing polyprenyl side chains. 

VITAMIN K. Sometimes referred to as the antihemmorhagic vitamin, and. earlier in its development, the prothrombin factor or Koagulations-vitamin, vitamin Kis a substituted derivative of naphthoquinone and occurs in several forms. The designationphylloquinone. or Ki, refers to 2-methyl-3-phytyl-l,4 naphthoquinone the designations famoquinone and prertyl-menaquinone, or K2, refer to 2-difarnesyl-3-methyl-1, 4-naphthoquinone. Menadione, sometimes called oil-soluble vitamin K3, is 2-methyl-1,4-naphthoquinone. The structure of phylloquinone is ... 

A simple and effective chemical method was developed for quantitatively reducing quinones, based on their reaction with metallic zinc and zinc ions [248]. Comparison of this method with conventional electrochemical reduction [249-252] revealed the chemical method to be considerably superior. A reduction reaction of vitamin Kj and other quinones in the presence of Zn° and Zn2+ eliminates the need to apply large negative potentials and may also be performed in the absence of any applied electrochemical potential. Some quinones used, such as UQ-10, menadione, and vitamin K, of the menaquinone series (MKs 4-10) could all be reduced to their corresponding hydroquinones in these conditions. 

Common Name Menadione Menaphthone Menaquinone Methylnaphthochinon(um) Vitamin K3... 

K Menaquinones (K2) Menadione (K3) Acetomenaphthone 50-100 p,g Water Soluble Vitamins... 

Vitamin K — Fat-soluble vitamin K is a group name for fat-soluble compounds which have in common a methylated naphthoquinone ring structure. Vitamin K is found in nature in two forms - Ki or phylloquinone is found in plants and vitamin K2 or menaquinone can be synthesized by many bacteria. Vitamin K3 (menadione) is a synthetic form of this vitamin. Vitamin K is used... 

Figure 5.1. Vitamin K vitamers and the vitamin K antagonists dicoumarol and war-farin. Relative molecular masses (Mr) phyUoquinone, 450.7 menaquinone-4, 447.4 menaquinone-5, 512.8 menaquinone-6, 580.0 menaquinone-7, 649.0 menaquinone-8,717.1 menadione, 172.2 menadiol diacetate, 258.3 dicoumarol, 336.3 and warfarin 308.3.

PhyUoquinone is vitamin Ki, menaquinones are vitamin K2, and the synthetic compounds menadione and menadiol are vitamin K3. In addition to menadione itself, menadiol diacetate (acetomenaphthone) is used in pharmaceutical preparations, and two water-soluble derivatives, menadione sodium bisulfite and menadiol sodium phosphate, have been used for administration of the vitamin by injection and in patients with malabsorption syndromes that would impair the absorption of menadione, phylloquinone, and menaquinones, which are lipid soluble. 

There are different physiological forms known as vitamins K, namely vitamin Kj (phylloquinone, phytonadi-one) and vitamin K2 (farnoquinone). There are active anologs and related compounds knows as vitamins K, namely menadiol diphosphate, menadione (vitamin K3 ), menadione bisulfite, phthiocol, synkayvite, menadiol (vitamin K4), menaquinone-n (MK-n), ubiquinone (Q-n), and plastoquinone (PQ-n) [3]. 

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