Microbial transformation of glycyrrhetinic acid by Mucor polymorphosporus.

Glycyrrhetinic acid (GA; 1) is one of the major constituents of a traditional Chinese medicine, the roots of Glycyrrhiza uralensis, called Gancao in Chinese. In the present paper, the biotransformation of GA by Mucor polymorphosporus (AS 3.3443) was investigated and eight metabolites were obtained. Based on their chemical and spectral data, the structures of the derivatives were respectively elucidated as 24-hydroxyglycyrrhetinic acid (2), 6 beta-hydroxyglycyrrhetinic acid (3), 7 alpha-hydroxyglycyrrhetinic acid (4), 7 beta-hydroxyglycyrrhetinic acid (5), 3-0-acetyl-7 beta-hydroxyglycyrrhetinic acid (6), 3-oxo-7 beta-liydroxyglycyrrhetinic acid (7), 15 alpha-hydroxyglycyrrhetinic acid (8), 3-oxo-15 alpha-hydroxyglycyrrhetinic acid (9), among which metabolites 3, 4, 6, 7 and 9 are new compounds.