New pyranonaphthazarin and 2-naphthoic acid derivatives from the mangrove endophytic fungus Leptosphaerulina sp. SKS032

Abstract Two new compounds, named leptospyranonaphthazarin A ( 1 ) and leptosnaphthoic acid A ( 2 ), together with four known compounds ( 3–6 ) were isolated from an endophytic fungus Leptosphaerulina sp. SKS032. Their structures were assigned using spectroscopic methods, computational methods, and single-crystal X-ray diffraction analysis. In the antibiotic assay, compounds 1 , 2 , and 6 exhibited antibacterial activities against Staphylococcus aureus with minimal inhibitory concentration (MIC) values of 25.0, 50.0, and 50.0 μg/mL, respectively.