New 1-O-Acyl α-L-Rhamnopyranosides and Rhamnosylated Lactones from Streptomyces sp., Inhibitors of 3α-Hydroxysteroid-dehydrogenase (3α-HSD)

抄録

Chemical screening with extracts of Streptomyces sp. (strain GT 61150) resulted in the detection, isolation, and structure elucidation of two new acyl α-L-rhamnopyranosides (1 and 2) and three new rhamnosyllactones A, B₁ and B₂ (3-5). Rhamnosyllactones B₁ and B₂ were obtained as a 5:1 mixture. The structures were confirmed by spectroscopic analysis, especially 2D-NMR techniques. The rhamnosyltransferase of our strain is able to connect the sugar moiety to heteroaromatic carboxylic acids and enols. The metabolites 1 and 4/5 as well as previously reported acylrhamnosides 6-11 inhibit the enzyme 3α-hydroxysteroid-dehydrogenase (3α-HSD).