8/9. Phylloquinon (vit K)

Question 1

Where do you find vit k?

Answer 1

Green plants, fresh alfalfa, meat, fish

Question 2

Structure and name : vit k1

Answer 2

Phylloquinone (in green plants, 20 carbons)

Question 3

Structure and name : vit k2

Answer 3

menaquinone ( product of bacterial synthesis, many different versions, 6 isoprene units are usual, but can change)

Question 4

Structure and name : vit k3

Answer 4

menadion (chemically synthesized, the side chain is formed in the mitochondria of hepatic cells.)

Question 5

Metabolism of vit K

Answer 5

Animals cannot synthesize naphtoquinone rings, plants and bacteria can from shikmic acid. In the proximal small intestines the bile has a direct role in the absorption process. There is a bacterial synthesis of Vit K2 in the colon.

Question 6

Where is Vit K stored?

Answer 6

It cannot be stored, therefore a continuous intake is necessary.

Question 7

How is vit K excreted?

Answer 7

Excreted by urine as glucoronide sulphate.

Question 8

Biochemical role:

Answer 8

-

Question 9

Deficiency:

Answer 9

Young chicks: hemorrhage (bleeding and long clotting time) Other species: difficult to get because they are supplimented with vit K2 from ruminal bacteria. Can get it if they are prevented from coprophagy. (rabbit) -Can also happen if they get drugs like antibiotics, microflora. -Newborn can get it, not permeable to placenta. -Bile is essential, no bile = no absorption End result: low blodd plasma prothrombin, long clotting time, hemorrhagic syndrome.

Question 10

Antagonists:

Answer 10

Dicumarol: chemically similar, sweet clover disease, bleeding syndrom. Warfarrin: anticoagulant, rat poison, very active, loooong clotting time.