Microbial transformation of asiatic acid by Alternaria longipes

Abstract

Asiatic acid is a major pentacyclic triterpene isolated from Centella asiatica. It shows a variety of bioactivities. In order to obtain its derivatives, potentially useful for detailed pharmacological studies, the substrate was subjected to incubations with selected micro-organisms. In this work, asiatic acid was converted into three new compounds: 2α,3β,23,30-tetrahydroxyurs-12-ene-28-oic acid (1), 2α,3β,22β,23-tetrahydroxyurs-12-ene-28-oic acid (2), and 2α,3β,22β,23,30-pentahydroxyurs-12-ene-28-oic acid (3) by the fungus Alternaria longipes AS 3.2875. The structures of the three metabolites were determined by 1D and 2D NMR spectral data.

Keywords:

• asiatic acid
• Alternaria longipes
• microbial transformation
• triterpene

Acknowledgements

This work was financially supported by the Beijing Natural Science Foundation (No. 7102103) and the Beijing NOVA Program (No. 2009B02).