Microbial transformations of hypolipemic E-guggulsterone

Biotransformation of E-guggulsterone (pregna-4,17(20)-cis-diene-3,16-dione) (1) by Aspergillus niger resulted in the formation of four near hydroxyl derivatives identified as 7 beta-hydroxypregna-4,17(20)-trans-diene-3,16-dione (2), 7 beta-hydroxypregna-4,17(20)-cis-diene-3,16-dione (3), 7 beta-hydroxypregn-4-ene-3,16-dione (4), and 7 beta,15 beta-dihydroxypregn-4-ene-3,16-dione (5). The biotransformation of 1 with Cephalosporium aphidicola also resulted in the formation of four new steroidal derivatives as 11 alpha-hydroxypregna-4,17(20)-trans-diene-3,16-dione (6), 11 alpha-hydroxypregna-4,17(20)-cis-diene-3,16-dione (7), 11 alpha,15 beta-dihydroxypregna-4,17(20)-trans-diene-3,16-dione (8), and 11 alpha,15 beta-dihydroxypregna-4,17(20)-cis-diene-3,16-dione (9). The structures of these compounds were elucidated on the basis of 1D and 2D NMR spectroscopic techniques.