Riboflavin (B2)

Question 1

Kinases

Answer 1

An enzyme (flavokinase) phosphorylates riboflavin to form FMN. 
Requires ATP.

Enhanced by magnesium.

Question 2

Absorption

Answer 2

Free riboflavin by energy dependent sodium independent carrier RFT2.

Bile facilitates absorption.

FMN dephosphorylated to riboflavin to enter portal blood to go to liver.

Question 3

Riboflavin carrier proteins (RCP)

Answer 3

Expressed in cells with high metabolic activity.

Pregnancy induces synthesis of RCP’s.

Mediate supply of riboflavin to fetus.

Question 4

RDA

Answer 4

1. 3 mg men

1. 1 mg women

Question 5

Assessment

Answer 5

Static: urine

Question 6

Redox

Answer 6

Dehydrogenation and hydroxylation reactions.

Question 7

B2 in energy production rxns

Answer 7

Oxidative decarboxylation of pyruvate.

Electron transport: succinate dehydrogenase composed of FAD and 3 S atoms.

Fatty acid beta oxidation

Question 8

B2 in other vitamin metabolism

Answer 8

B6, B12, and folate metabolism.

Niacin from tryptophan (NE).

Reduces glutathione which recycles vitamin C

Question 9

Deficiency

Answer 9

Ariboflavinosis: Cheilosis (mouth sores), inflamed tongue, neuropathy, weakness.

Rarely deficient in isolation. Usually alongside other deficiency due to being used in metabolism of folic acid, B6, vit K, B12, vit C recycle.

Question 10

Megadosing/ UL

Answer 10

No UL.

Migraine therapy and cataract prevention.

Question 11

Excretion

Answer 11

Urine

Question 12

Sources

Answer 12

Animal products: milk, eggs, meat.
Legumes. Green vegetables.

Found as FMN of FAD.