| Abstract: | Ceanothic acid (1) is the major triterpene isolated from Parliurus ramosissitnus (Rhamnaceae) which possesses three methyl groups corresponding to the 4,4,14α-trimethyl groups in lanosterol (5). Microbial transformation of 1 and its 3-dehydro-2,28-dimethyl ester derivative (3) with Mycobacterium sp. (NRRL B-3805) resulted in the methylation of the carboxylic functions and C-1 epimerization, respectively. Although this work indicates that 1 is not a suitable substrate for 4,4,14α-tridemethylation, esterification of the carboxylic function and the C-1 epimerization reaction in ceanothic acid and its derivative is the first observation with this microorganism. |
