<p>A new <i>α</i>-pyrone derivative, phomopyrone A (<b>1</b>), together with two known compounds (<b>2</b>–<b>3</b>), was isolated from the culture of the mangrove endophytic fungus <i>Phomopsis</i> sp. HNY29-2B. Their structures were determined by detailed analysis of spectroscopic data. The configuration of <b>1</b> was further confirmed by X-ray diffraction. All isolated compounds were evaluated for antibacterial and antioxidative activities. Compound <b>2</b> exhibited antibacterial activities with minimal inhibition concentration (MIC) values of 25 and 50 μM against <i>Bacillus subtilis</i> and <i>Pseudomonas aeruginosa</i>, and compound <b>3</b> showed activities against <i>Staphylococcus aureus</i> and <i>B. subtilis</i> with MIC values of 25 and 50 μM, respectively.</p
