Transformation of steviol-16alpha,17-epoxide by
Streptomyces griseus and Cunninghamella bainieri
楊禮明;林淑娟;廖嘉鴻
Chang SF;Yang LM;Hsu FL;Hsu JY;Liaw JH;Lin SJ
Abstract
Eight new ent-beyerane metabolites, 5-8, 12, and 14-16, and four new ent-kaurane metabolites, 3, 10, 11, and 13, together with two known metabolites, 4 and 9, were isolated from the microbial transformations of steviol-16alpha,17-epoxide using Streptomyces griseus ATCC 10137 and Cunninghamella bainieri ATCC 9244. The structures of the metabolites were characterized by IR, HRFABMS, and 1D and 2D NMR data. In addition, a GRE (glucocorticoid response element)-mediated luciferase reporter assay was used to initially screen for the biological activity of the 11 metabolites and stevioside. Steviol (1), steviol-16alpha,17-epoxide (2),
ent-11alpha,13,16alpha,17-tetrahydroxykauran-19-oic acid (3),
ent-17-hydroxy-16-ketobeyeran-19-oic acid (4), ent-9alpha,13-dihydroxy-16beta,17-epoxykauran-19-oic acid (10),
ent-9alpha,17-dihydroxy-16-ketobeyeran-19-oic acid (12), ent-1beta,17-dihydroxy-16-ketobeyeran-19-oic acid (14), and stevioside showed
significant effects; in particular, stevioside showed almost equal potency as dexamethasone.
