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Fat soluble VITAMINS Fat soluble VITAMINS Vitamin KVitamin K

Learning objectives Role of vitamin K regarding prothrombin formation

in liver. Natural and synthetic form of vitamin K. From where we get vit K naturally. Daily requirement of vit K. Deficiency symptoms of vit K. Why generally recommend vit K inj to newly born

babies. Toxic effect of high dose of vit K. Chemistry, functions, deficiency and daily

requirement of Tocopherol.

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Vitamin K Vitamin K is essential for the formation of

prothrombin couple in the liver & therefore maintaining the normal prothrombin level in the blood.

It exist in several forms, for example, in plants as phylloquinone (vitamin K1), & in intestinal bacterial flora as menaquinone (vitamin K2).

A synthetic form of vitamin K3 – menadione.

Vitamin K

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Structures of vit K

C11H8O2C11H8O2

Vitamin K1 Vitamin K2

Vitamin K3 (Menadione)

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Source Source In plants (vit K1) it is chiefly present in green in green

leafyleafy tissues (alfalfa, spinach), also found in cauliflower, cabbage, tomatoes, soya beans, rice etc.

In human alimentary canal, it is synthesized by intestinal floraintestinal flora & endogenously supplied to supplied to the bodythe body.

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Requirement: Requirement:

120 120 μμg/dayg/day for adult males & 90 90 μμg/dayg/day for adult females.

Functions of vit K:Functions of vit K: Vit K is required in the hepatic synthesis of

prothrombinprothrombin & blood clottingblood clotting factors II, VII, IX & X.

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Deficiency of vit k (Hypovitaminosis)Deficiency of vit k (Hypovitaminosis) A true vit k deficiency is unusualunusual because

adequate amountsadequate amounts are generally produced by intestinal bacteriaintestinal bacteria or obtained from the dietdiet.

In case of chemotherapy (antibioticsantibiotics) amount of vit K is depressed, that can lead to hypoprothrombinemia in malnourishedmalnourished individual, e.g: a debilitated geriatric patient.

Newborns have sterile intestinesterile intestine which lack the bacteria that synthesize vit K. So, it is recommended that all newbornsall newborns receive a single IM dosesingle IM dose of vit K as prophylaxisprophylaxis against hemorrhagic disease.

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Hypervitaminosis Hypervitaminosis

Prolonged administration of large doses of synthetic vit K (menadione) can produce hemolytic anemiahemolytic anemia & jaundicejaundice in the infant, due to toxic effects on RBCstoxic effects on RBCs; therefore, it is no no longer usedlonger used to treat vit K deficiency.

Normal Hemolytic anemia Jaundice

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Vitamin E

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Vitamin E (TocopherolTocopherol)

The vitamin E consist of eight naturally eight naturally occurringoccurring tocopherols, of which α-tocopherol is the most activemost active.

They are commercially important, as they are antioxidantantioxidant for fats, oils, vitamin A & carotenes.

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Structural formula of -tocopherol

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Occurrence Plant source: All green plantsgreen plants contain

considerable amount of tocopherols. Vegetable Vegetable fatsfats are the richestrichest naturalnatural source (wheat germ oil).

Legumes, nuts, cereals are also important source.

Only a small amountssmall amounts are present in olive & coconut oils.

Animal tissue contain relatively less amounts. Milk is poor in this factor.

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Requirements of vit E: The RDA for α-tocopherol is 15mg15mg for adults. The vit E requirement increasesincreases as the intakeintake

of polyunsaturated fatty acidpolyunsaturated fatty acid increases.

Deficiency of Vit E: In human – not takes placenot takes place due to its wide

occurrence in vegetablevegetable. Vit-E deficiency may be found in

lipoproteinemialipoproteinemia & in diseases such as sprue, obstructive jaundice etc.

Vit E deficiency in adults, is usually associated with defective lipid defective lipid absorption or transport. The signs are; sensitivitysensitivity of erythrocytes to peroxide, & the appearance appearance of abnormal cellular membrane.

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Functions Vit E participates in the formationformation of

intercellular substance, collagencollagen & elastic elastic fibersfibers derived from it.

It is important antioxidantantioxidant & protectprotect easily oxidizable vit A. Tocopherols are usually added to commercial oily foodscommercial oily foods to prevent their oxidation.

Vitamin E Prevents massive hepatic necrosishepatic necrosis produced on diet deficient in Sdeficient in S containing amino acids.

It protects lungs tissueslungs tissues from polluted air. Also protects & stabilizes the cell membranecell membrane. Vitamin E also takes part in the synthesis of synthesis of

hemeheme. More recent functions are its curative action

on menopausal disordersmenopausal disorders, male sterilitymale sterility & prurituspruritus etc.

“Every healthy person, after 45 yrsafter 45 yrs must take vit-E daily to prevent heart heart attackattack & to retard aging aging processprocess”.

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References & keys Mushtaq Ahmad vol-IIMushtaq Ahmad vol-II

Hashmi’s Textbook of Medical BiochemistryHashmi’s Textbook of Medical Biochemistry

Debilitate = weak Geriatric: old age people Sprue: tropical disease - deficiency of nutrients absorption from intestine,

diarrhoea, enemia.