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