Polyketide Derivatives, Guhypoxylonols A-D from a Mangrove Endophytic Fungus sp. GXNU-Y45 That Inhibit Nitric Oxide Production.

Four undescribed compounds, guhypoxylonols A (), B (), C (), and D (), were isolated from the mangrove endophytic fungus sp. GXNU-Y45, together with seven previously reported metabolites. The structures of - were elucidated based on analysis of HRESIMS and NMR spectroscopic data. The absolute configurations of the stereogenic carbons in - were established through a combination of spectroscopic data and electronic circular dichroism (ECD). Compounds - were evaluated for their anti-inflammatory activity. Compounds , , , and showed an inhibitory activity against the production of nitric oxide (NO), with the IC values of 14.42 ± 0.11, 18.03 ± 0.14, 16.66 ± 0.21, and 21.05 ± 0.13 μM, respectively.