A new isocoumarin from mangrove endophytic fungus (No. dz17) on the South China Sea coast

A new isocoumarin, 3,4-dihydro-6-methoxy-8-hydroxy-3,4,5-trimethylisocoumarin-7-carboxylic acid methyl ester (1), together with three known compounds, 3,4-dihydro-4,8-dihydroxy-3,5-dimethylisocoumarin (2), 3,4-dihydro-8-hydroxy-3-methylisocoumarin-5-carboxylic acid (3), and Entinclole SB (4) were isolated from the mangrove endophytic fungus (No. dz17). The structure of the compound 1 was elucidated by analysis of spectroscopic data. Primary bioassays showed that 1 exhibited weak cytotoxicity against Hep-2 and HepG2 cells.