Antioxidative Indenone and Benzophenone Derivatives from the Mangrove-Derived Fungus NSHSJ-2.

Seven new polyketides, including four indenone derivatives, cytoindenones A-C (, -), 3'-methoxycytoindenone A (), a benzophenone derivative, cytorhizophin J (), and a pair of tetralone enantiomers, (±)-4,6-dihydroxy-5-methoxy--tetralone (), together with a known compound () were obtained from the endophytic fungus NSHSJ-2 isolated from the fresh stem of the mangrove plant . Compound represented the first natural indenone monomer substituted by two benzene moieties at C-2 and C-3. Their structures were determined by the analysis of 1D and 2D NMR, as well as mass spectroscopic data, and the absolute configurations of (±)- were determined on the basis of the observed specific rotation value compared with those of the tetralone derivatives previously reported. In bioactivity assays, compounds , - showed potent DPPH· scavenging activities, with EC values ranging from 9.5 to 16.6 µM, better than the positive control ascorbic acid (21.9 µM); compounds - also exhibited DPPH· scavenging activities comparable to ascorbic acid.