Chemically biotin is a rather complex substance containing a sulphur heterocycle ring, and a nitrogen heterocyclic ring, fused toge­ther. Its structure is as follows :

Biotin is very much soluble in water but insoluble in fat sol­vents. It is reasonably stable towards dilute acids, alkali and heat.

Occurrence and availability of Biotin:

It is found in abundance in egg- yolks, liver, kidney, milk, yeast, wheat and other seeds. Its other good sources are roasted peanuts, cauliflower, dried peas, chocolate and dried lima beans.

It may be synthesized by intestinal bacteria which is a potent source than that obtained from the diet.

Daily requirement:

Biotin is generally required by all animals investigated 50 far. It is essential for rats, pigs, rabbits, monkeys, dogs and men and chicks. The daily requirement of a man is 0-5 mg.

Biotin deficiency or avitaminosis:

The deficiency of biotin in rat’s cause’s special dermatitis, marked by sealiness and desquam­ation (shedding of scales), the spectacled eye condition is also apt to appear. In addition, there is a loss of weight leading to extreme emaciation and death.

It can also prevent the birth of young. Deficiency of this vitamin in hens results in high embryonic morta­lity and skeletal deformities in chicks.

In man, although the deficiency of biotin has not been noticed but experimental deficiency leads to polar desquamation, noticeable susceptibility to fatigue and muscular pains, and heart distresses.