A new anthraquinone compound, 5-acetyl-2-methoxy-1,4,6-trihydroxy-anthraquinone (1), together with four known naphthoquinones (2-5), were isolated from the culture of the mangrove fungus (No. b77). All the isolated compounds (1-5) and the acetyl derivative (1a) were established by comprehensive analysis of the spectral data, especially 1D- and 2D-NMR (HMQC and HMBC) spectra. In the primary bioassays, compound 3 showed strong inhibitory effects on the growth of hepG2 and hep2 cells, with IC(50) values of 1.0 and 2.5 microg mL(-1), respectively.