Structural modification of echinocystic acid (EA), a pentacyclic triterpenoid with wide spread biological activities was investigated by microbial transformation. Microbe-mediate transformation of EA was carried out by filamentous fungus Cunninghamella blakesleana CGMCC 3.910. Four metabolites 3β, 7β, 16α-trihydroxy-olean-12-en-28-oic acid (EA-2); 3β, 7β, 16β,19β-tetrahydroxy-olean-12-en-28-oic acid (EA-3); 3β, 7β, 16α, 21β-tetrahydroxy-olean-12-en-28-oic acid (EA-4); 3β, 7β, 16α-trihydroxy-olean-11, 13(18)-dien-28-oic acid (EA-5) were produced. Structures of transformed products were elucidated by 1D and 2D NMR and HR-MS data. EA-3 and EA-4 were new compounds.
Keywords: Biocatalysis; Echinocystic acid; Fungus; Pentacyclic triterpenoids.