Aromatic Polyketides and Hydroxamate Siderophores from a Marine-Algae-Derived Streptomyces Species.

Four new aromatic polyketides, wailupemycins M-P (1-4), and two new hydroxamate siderophores, streptamides A (5) and B (6), together with the previously reported nocardamine (7), were isolated from the marine-algae-derived Streptomyces sp. OUCMDZ-3434. Wailupemycins M-P (1-4), possessing an α-pyrone moiety, were isolated from the extract of a liquid fermentation, and the siderophores (5-7) were isolated from the extract of a solid fermentation. Their structures were assigned based on detailed spectroscopic analysis and quantum chemical calculations. Compounds 5-7 were capable of binding Fe(III). Compound 5 can form a tighter Fe(III) complex than that of deferoxamine B mesylate (DFB).