BIOTIN • 553 



oxybiotin have activities up to 10 per cent of that of biotin for a number 

 of organisms. 



NH 2 NH 2 NH 2 NH 2 



H— C C— H H— C C— H 



H 2 C CH— (CH 2 ) 4 — COOH 



V 



I I 



CH 3 CH 2 — (CH 2 )<— COOH 



cis-S ,4-diamino-2-tetrahydro- f ,t]-diaminopelargonic acid 



thiophenevaleric acid 



H-i 



NH 2 NH 2 

 I 

 C— H 



H 2 C CH— (CH 2 ) 4 — COOH 



V 



cis-3,4-diamino-2-tetrahydrofuranvaleric acid 



On the basis of the activity of the diaminocarboxylic acid derived from 

 biotin, it has been proposed that biotin may function as a coenzyme 

 involved in utilization of carbon dioxide. 60 



Slight activity has been noted for an oxybiotin analogue in which the 

 valeric acid side chain has been replaced by a methyl group. The activity 

 of the 4-pentanol derivative corresponding to oxybiotin may be the 

 result of oxidation of the compound to oxybiotin. Analogous to this 

 result, it has been reported that replacement of the alcohol group to form 

 a number of sulfur analogues results in compounds possessing slight 

 activity. Thus, DL-hexahydro-2-oxo-lH-furo [3,4] imidazole-4- (5-pen- 

 tanesulfonic acid) has slight growth-promoting activity for both Lacto- 

 bacillus arabinosus and Saccharo?nyces cerevisiae; and both DL-hexa- 

 hydro-2-oxo-4- (5-benzylthiopentyl) -lH-furo [3,4] imidazole and DL-hex- 

 ahydro-2-oxo-4-(5-mercaptopentyl)-lH-furo [3,4] imidazole are slightly 

 active in replacing biotin for Lactobacillus arabinosus. 61 



Inhibitory Analogues of Biotin 



Desthiobiotin and Related Compounds. Desthiobiotin, which was 

 obtained by du Vigneaud and associates 10 during structural studies on 

 cleavage of biotin with Raney's nickel, was found to possess growth- 

 promoting activity comparable to biotin for Saccharo?nyces cerevisiae.* 1 

 On the other hand, it was found to prevent competitively the utilization 

 of biotin by Lactobacillus casei. i2 < 51 The activities of this derivative 

 stimulated the preparation and testing of numerous analogues. These 

 compounds are listed in Table 14. The inhibitory activities, unless indi- 



