Riboflavin (Vitamin B2)

Question 1

What is the structure of riboflavin?

Answer 1

Isoalloxazine linked to ribitol (ribose alcohol)

Question 2

What are the coenzyme forms of riboflavin?

Answer 2

FMN (Flavin Mononucleotide)
FAD (Flavin Adenine Dinucleotide)

Question 3

What are the roles of FAD and FMN in metabolism?

Answer 3

Participates in Oxidation-reduction reactions i.e. electron transfer in biochemical reactions

Question 4

What are flavoenzymes?

Answer 4

Enzymes containing riboflavin

Question 5

What are the functions of FAD and FMN?

Answer 5

Question 6

What are the sources of riboflavin?

Answer 6

Excellent source: Milk (2 cups of milk will supply 1/2 the RDA)
Good sources: Mushrooms, leafy green vegetables, meat, eggs, yeast and liver

Question 7

What factors may lead to the destruction of riboflavin?

Answer 7

Milling of cereals (up to 60% loss)
UV light destroys riboflavin (up to 70% loss)

Question 8

High dose of riboflavin effect on urine

Answer 8

Orange color urine

Question 9

What are some clinical uses of riboflavin?

Answer 9

Used in phototherapy treatment of neonatal jaundice - light irradiates the infants, breaks down bilirubin (compound causing the jaundice) and naturally occurring riboflavin within the infant’s blood, so extra supplementation is necessary
High dose riboflavin is used to prevent migraines

Question 10

What are some symptoms of riboflavin deficiency?

Answer 10

Riboflavin deficiency is classically associated with the oral-ocular-genital syndrome
Glossitis: Inflammation of tongue
Cheilosis: Swollen, cracked bright red lips
Angular Stomatitis: Inflammation at the corners of mouth
Seborrhic dermatitis: Scaly plaques in the areas of greatest sebum production
Circum-corneal vascularization: Development of blood capillaries around the cornea
Photophobia
Scrotal dermatitis

Question 11

How is riboflavin activity assessed?

Answer 11

Activity of RBC Glutathione reductase enzyme is used to assess riboflavin status