New chlorinated xanthone and anthraquinone produced by a mangrove-derived fungus Penicillium citrinum HL-5126.

Two new chlorinated metabolites 4-chloro-1-hydroxy-3-methoxy-6-methyl-8-methoxycarbonyl-xanthen-9-one (1) and 2'-acetoxy-7-chlorocitreorosein (2), together with three known compounds (3-5), were obtained from the EtOAc extract of the endophytic fungus Penicillium citrinum HL-5126 isolated from the mangrove Bruguiera sexangula var. rhynchopetala collected in the South China Sea. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. All compounds were evaluated for their antibacterial and topoisomerase I inhibitory activities. Compound 2 exhibited antibacterial activity against Vibrio parahaemolyticus with an MIC value of 10 μm.