Microbial hydroxylation and glycosidation of oleanolic acid by <i>Circinella muscae</i> and their anti-inflammatory activities

Abstract

Biotransformation of oleanolic acid (OA) by <i>Circinella muscae</i> AS 3.2695 was investigated. Nine hydroxylated and glycosylated metabolites (<b>1-9</b>) were obtained. Their structures were elucidated as 3β,7β-dihydroxyolean-12-en-28-oic acid (<b>1</b>), 3β,7β,21β-trihydroxyolean-12-en-28-oic acid (<b>2</b>), 3β,7α,21β-trihydroxyolean-12-en- 28-oic acid (<b>3</b>), 3β,7β,15α-trihydroxyolean-12-en-28-oic acid (<b>4</b>), 7β,15α-dihydroxy- 3-oxo-olean-12-en-28-oic acid (<b>5</b>), 7β-hydroxy-3-oxo-olean-12-en-28-oic acid (<b>6</b>), oleanolic acid-28-O-β-D-glucopyranosyl ester (<b>7</b>), 3β,21β-dihydroxyolean-12-en-28- oic acid-28-O-β-D-glucopyranosyl ester (<b>8</b>), and 3β,7β,15α-trihydroxyolean-12-en- 28-oic acid-28-O-β-D-glucopyranosyl ester (<b>9</b>) by spectroscopic analysis. Among them, compounds <b>4</b> and <b>9</b> were new compounds. In addition, anti-inflammatory activities were assayed and evaluated for the isolated metabolites. Most of the metabolites exhibited significant inhibitory activities on lipopolysaccharides-induced NO production in RAW 264.7 cells.