BIOTIN 



559 



CO 



/\ 



HN NH 



\ / 



HC — CH 



H 2 C CH— (CH 2 ) 3 — COOH 



H2C — OH2 



y-{2,3-ureylenecyclohexyl)butyric acid 



CO 



HN NH 



HC— CH 

 / \ 



H 2 C CH— (CH 2 ) 4 — COOH 



H 2 C — CH 2 



b-{2 ,3-ureylenecyclohexyl) 

 valeric acid 



CO 



/ 



HN 



NH 



HC— CH 

 / \ 



H 2 C CH 2 



H 2 C — CH— (CH 2 ) 3 — COOH 

 y-(8,4-ureylenecyclohexyl)butyric acid 



analogues and stereoisomers, the biological activities of the diastereoiso- 

 mers were almost identical. 



Table 17. Ureylenebenzene and Cyclohexane Derivatives as Inhibitory Biotin Analogues 



Stereoisomeric modifications distinguished only by melting point. 

 6 Inhibits growth of Lactobacillus arahinosus. 



Avidin 



On a well balanced diet to which relatively large quantities of dried 

 egg white have been added, rats lose their hair and develop a severe 

 dermatitis and skin hemorrhages; these symptoms are accompanied by 



