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.

中文翻译：

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灰链霉菌和枯草芽胞杆菌转化甜菊醇-16α，17-环氧化物。

从微生物中分离出八种新的五氢苯丙醚代谢物5-8、12和14-16，以及四种新的五氢呋喃新物代谢物3、10、11和13，以及两种已知的代谢物4和9。用灰链霉菌ATCC 10137和Cunninghamella bainieri ATCC 9244转化甜菊醇16α，17-环氧化合物。通过IR，HRFABMS以及1D和2D NMR数据对代谢产物的结构进行了表征。此外，使用GRE（糖皮质激素反应元件）介导的萤光素酶报告基因检测法初步筛选了11种代谢产物和甜菊糖的生物活性。甜菊醇（1），甜菊醇16alpha，17-环氧（2），ent-11alpha，13,16alpha，17-四羟基kauran-19-oic酸（3），ent-17-羟基-16-ketobeyeran-19-oic酸（4），ent-9alpha，13-二羟基-16beta，17-环氧花兰素-19-oic酸（10），ent-9alpha，17-二羟基-16-酮贝叶烷-19-oic酸（12），ent-1beta，17-二羟基-16-酮贝叶烷-19-oic酸（14）和甜菊糖苷显示出明显的作用; 特别是，甜菊糖苷显示出与地塞米松几乎相同的效力。