Indimicins A–E, Bisindole Alkaloids from the Deep-Sea-Derived Streptomyces sp. SCSIO 03032

Five new bisindole alkaloids, indimicins A–E (1–5), bearing a unique 1′,3′-dimethyl-2′-hydroindole moiety, were isolated from the marine-derived Streptomyces sp. SCSIO 03032, along with two new compounds, lynamicins F and G (6 and 7). Their planar structures were elucidated by detailed interpretation of their MS and NMR spectroscopic data, and the absolute configurations were determined by X-ray crystallographic analysis (for 1), comparison of CD spectra (for 2–4), and quantum chemical calculations (for 5). Indimicin B (2) exhibited moderate cytotoxic activity toward the MCF-7 cell line.