Strepamrisides C and D: two new rhamnosides from Streptomyces amritsarensis 13-85

Two new rhamnosides, strepamrisides C and D (1 and 2), together with two known rhamnosides, maculosin-O-α-L-rhamnopyranoside (3) and 2-pyrrolylcarbonyl-α-L-rhamnopyranoside (4) were isolated from Streptomyces amritsarensis 13–85. Their structures were elucidated by comprehensive spectroscopic analyses, including nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and chemical derivatization. Compounds 2 and 3 showed inhibitory activity against α-glucosidase.