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).