Transformation of Steviol-16r,17-epoxide by
Streptomyces griseus and Cunninghamella bainieri
張淑芬
Shwu-Fen Chang;Li-Ming Yang;Feng-Lin Hsu;Ju-Yin Hsu;Jia-Horng Liaw;Shwu-Jiuan
Lin
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-16a,17-epoxide using
Streptomyces griseus ATCC 10137 and Cunninghamella bainieri ATCC 9244. The structures of the metabolites were characterized by IR, HRFABMS, and ID 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-16a,17-epoxide (2),
ewf-11α,13,16α,17-tetrahydroxykauran-19-oic acid (3), ent-17-hydroxy-16-ketobeyeran-19-oic acid (4),
ent-9α,13-dihydroxy-16β,17-epoxykauran-19-oic acid (10), ent-9a,17-dihydroxy-16-ketobeyeran-19-oic acid (12),
ent-1β,17-dihydroxy-16-ketobeyeran-19-oic acid (14), and stevioside showed significant effects; in particular, stevioside showed almost equal potency as dexamethasone
