Angucycline Glycosides from Mangrove-Derived Streptomycesdiastaticus subsp. SCSIO GJ056.

Nine new angucycline glycosides designated urdamycins N1⁻N9 (1⁻9), together with two known congener urdamycins A (10) and B (11), were obtained from a mangrove-derived Streptomycesdiastaticus subsp. SCSIO GJ056. The structures of new compounds were elucidated on the basis of extensive spectroscopic data analysis. The absolute configurations of 6⁻9 were assigned by electronic circular dichroism calculation method. Urdamycins N6 (6) and N9 (9) represent the first naturally occurring (5R, 6R)-angucycline glycosides, which are diastereomers of urdamycins N7 (7) and N8 (8), respectively.