Biotin
Biotin, one of the members of the group of B vitamins, has been known by a variety of names including bios, vitamin H, and coenzyme R. As early as 1916 the toxicity of diets high in egg white was observed. Some years later Boas described egg white injury in rats fed diets containing raw egg white as the source of protein. She described muscle incoordination, dermatitis, loss of hair, and nervous manifestations as symptoms of this syndrome. She observed that cooked egg white was not toxic and that liver, yeast, and certain other foods apparently contained a substance that protected rats against the toxicity of the raw egg protein.
The protective substance was called vitamin H by Gyorgy. Lease and Parsons showed that chicks were subject to egg white injury. Williams and co-workers some six years later demonstrated that egg white injury in rats and in chicks was actually due to an antivitamin in egg white. This substance, known as avidin, is a basic protein, and its ability to inactivate biotin was confirmed in 1941. Previous to this time a potent growth stimulant for yeast had bern isolated from dried egg yolk by Kogl and Tonnis and named biotin. Coenzyme R was the name given another growth factor isolated in 1933. It was in 1940 that Gybrgy. du Vigneaud, d their co-workers announced the identity of vitamin H (anti-egg white injury factor) nzyme R, and biotin. Du Vigneaud and co-workers characterized biotin and published its cture in 1942. Harris and others announced the synthesis of d-biotin in 1943. Improvements in the synthesis have been numerous, and at present biotin is readily available to the research rker. The elucidation of the nature of biotin is unique among vitamin studies.
Real progress developed after the demonstration of the toxic effect of egg white, and then - was shown that foods contained a protective substance, vitamin-like in nature. Later it as demonstrated that avidin of egg white combines with and inactivates biotin of foods and perrhaps that produced by bacteria in the intestine leading to a dietary deficiency.
