Microbial transformation of corosolic acid by Fusarium equiseti and Gliocladium catenulatum

Abstract

The growing cultures of Fusarium equiseti CGMCC 3.3658 and Gliocladium catenulatum CGMCC 3.3655 were used for the first time in the structural modification of corosolic acid (1). Four new metabolites were obtained. F. equiseti CGMCC 3.3658 converted 1 into 2α,3β,15α-trihydroxyurs-12-en-28-oic acid (2) and 2α,3β,7β,15α-tetrahydroxyurs-12-en-28-oic acid (3). G. catenulatum CGMCC 3.3655 transformed 1 into 2α,21β-dihydroxy-A-homo-3α-oxours-12-en-28-oic acid (4), and 2α,3α,21β-trihydroxyurs-12-en-28-oic acid (5). The structures of four metabolites were determined by ¹H NMR, ¹³C NMR, DEPT, HSQC, HMBC, and NOESY spectral data. Cytotoxicities in vitro of corosolic acid and four metabolites against three tumor cell lines, viz. Hela, A549, and SGC-7901, were evaluated by the classical 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay.

Keywords:

• corosolic acid
• microbial transformation
• pentacyclic triterpene
• cytotoxicity