Two new <i>α</i>-pyrone derivatives from the marine-derived <i>Streptomyces</i> sp. SYPHU 0003

Four <i>α</i>-pyrone derivatives (<b>1–4</b>) were isolated from marine-derived <i>Streptomyces</i> sp. SYPHU 0003, among which two new compounds (<b>1</b> and <b>2</b>). The structures and absolute configurations of compounds <b>1–4</b> were established by comprehensive spectroscopic analyses (MS and NMR), combined with ECD calculations and modified Mosher′s method. Antibacterial activity revealed that compounds <b>1–4</b> exhibited identical activity against <i>Acinetobacter baumannii</i> with the MIC values of 64 μg mL⁻¹.