Vitamin B2 is water soluble vitamin. It is yellow vitamin. It produce from plants. It is stable to heat in natural acid solution

2. Ribose alcohol: D-Ribitol
Tricyclic Heterocyclic structure
Isoalloxazine
Ribityl is alcohol derived from pentose
sugar D-ribose
 A= Pyrimidine ring
 B= Azine ring
 C=Benzene ring

3. FAD & FMN both are biological active form
FMN: phosphoric acid ribityl alcoholic
group at C5 flavin-ribityl-po4
FAD: linked to adenine nucleotide through
pyrophosphate linkage
Flavoprotein = FMN/FAD + Protein
Metallo-flavinprotein

4. Higher plants form Riboflavin protein
Occurs in ‘free form’ & ‘nucleotide’
Human and animal can’t synthesize
Metabolism
Absorb in small intestine
Blood/plasma level: 2.5 - 4.0µgm% . Conc
in R.B cells 15 - 30µg/100gm,leucocyte
and platelets 250µg/100gm

5. 50% as nucleotide in urine, Daily urinary
excretion 0.1 – 0.4mg
Milk: 40 – 80% free form
Faeces: 500 – 750µg daily from
unabsorbed bacteria
FMN/FAD act as coenzyme in H-transfer
reaction

6.  Antagonist
 Dichlororiboflavin: Replace two –CH3 groups
In riboflavin with Cl atoms
 Iso-riboflavin:-CH3 group shifted to another
position
 No definite disease entity
 In human lesions of mouth, tongue, skin with
weakness report

7. Adults: 1.5 – 1.8mg
Women in later hall of pregnancy: 2.0mg
Children : 0.6mg
Adolescence: 2.0 – 2.5mg