ANALOGUES 



C2H5OOC COOC2H5 



I I 



+ 



CH— CH 



II II 



CH C . (CH2), . CH^OH 



\/ 

 O 



ClOC COCl 



I I 



c — c 



II II 



CH C . (CHa)^ . CHaOAc 



o 



HOOC COOH 



II II 



CH C . (CHa)^ . CHaOH 



\/ 

 O 



C2H5OOC . NH NH . COOC2H6 



H 



CO 



NH 



NH 



I H I 

 CHj CH 



V 



(CH2), 



cultures of L. arabinosus and 5. faecalis, ^^ and subtracting the true 

 biotin content, as indicated by the response of S. faecalis, from the 

 apparent biotin content, as indicated by L. arabinosus. It can also 

 be estimated by first destroying biotin with Raney nickel, which does 

 not affect oxybiotin and then assaying the solution microbiologically.^^ 



Oxybiotin cured egg-white injury in the rat, being 5 to 10 % as 

 effective as ^-biotin in this respect. 2*' ^^» ^^ It also cured s3miptoms 

 of biotin deficiency in chicks, having 17 to 33 % of the activity of 

 ^-biotin.39. 40 j^g activity fell off with increasing dosage, and oxy- 

 biotin was found in liver and muscle when large doses were given. ^^^ 



The diamino-carboxylic acid, 3 : 4-diaminotetrahydrofuran-2 -val- 

 eric acid, from oxybiotin was inactive for 5. cerevisiae and for L. 

 arabinosus. ^^ Replacement of the carboxyl group of oxybiotin by a 

 primary alcohol group gave a compound with 1/300 the activity of 

 biotin. Oxybiotin, its methyl ester and the corresponding alcohol 

 combined with avidin in the same molecular proportion as did biotin. ^^ 



Rubin et al.^ assumed that oxybiotin was converted to biotin or a 

 vitamer of similar activity, but it is now certain that oxybiotin does 

 not owe its activity to conversion into biotin. K. Hofmann and 

 T. Winnick^i developed a method of estimating oxybiotin by first 

 destro5dng any biotin present by oxidation with o-oi N-potassium 



451 



