Vertirhodins A-F, C-Linked Pyrrolidine-Iminosugar-Containing Pyranonaphthoquinones from Streptomyces sp. B15-008.

Six novel pyranonaphthoquinones, vertirhodins A-F (1-6), were discovered from a soil-derived Streptomyces sp. B15-008. Their chemical structures and absolute configurations were determined using nuclear magnetic resonance and comparison of experimental and theoretical electronic circular dichroism spectra. The vertirhodins feature an unusual C-8 N-methyl-2-pyrrolidinemethanol moiety, a 5,14-epoxide rarely seen in streptomyces-derived natural products, and a C-13 hydroxyl group that forms the semiquinone. A plausible ver biosynthetic gene cluster was identified through whole genome sequencing and provides insights into these features.