New Derivatives from Microbial Transformation of ent-Kaur-16-en-19-oic Acid by Cunninghamella echinulata.

Biotransformation of ent-kaur-16-en-19-oic acid using fungus Cunninghamella echinulata resulted in two novel hydroxylated metabolites together with five known compounds. Their structures were elucidated by means of extensive NMR and HR-ESI-MS data analysis. The eight compounds were measured for their cytotoxicity against the human breast carcinoma (MCF-7) and human hepatoblastoma (HepG-2) cell lines. Seven compounds showed no cytotoxicity to the two cell lines. One compound displayed moderate cytotoxicity against HepG-2 and MCF-7 with the IC50 values of 12.6 and 27.1 μM, respectively.