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January 2, 1943

Current Comment

JAMA. 1943;121(1):54. doi:10.1001/jama.1943.02840010056015

STRUCTURE OF BIOTIN  Success seems to have crowned the attempts of du Vigneaud of Cornell University Medical College and his collaborators to determine the exact chemical nature of biotin. The structural formula of this substance has now been published.1 The compound is bicyclic and possesses a five membered urea ring, a ring containing sulfur in thio-ether linkage, and a fatty acid side chain. This chemical agent exerts a biologic effect in extremely great dilution and may be classed as one of the most active substances known. The growth promoting effect of biotin on an appropriate strain of yeast is noticeable when the factor is present in a concentration of only 1 part in 400 billion.2 This may be compared with the dilating effect of epinephrine on the pupil of the frog eye, which can be demonstrated in a concentration of 1 in 20 million, and with the effect