Bioactive polyketides from the sea fan-derived fungus Penicillium citrinum PSU-F51

Five new polyketides including two benzopyranones (1 and 2), one isochroman (3) and two anthraquinone-citrinin derivatives (4 and 5) were isolated from the sea fan-derived fungus Penicillium citrinum PSU-F51 together with thirteen known compounds. The structures were determined by spectroscopic methods. The anthraquinone-citrinin derivatives are rare natural products. Compound 4 displayed moderate antibacterial activity against both Staphylococcus aureus and methicillin-resistant S. aureus with equal MIC values of 16 μg/mL, while the known coniochaetone A displayed moderate antifungal activity against Candida albicans with MIC value of 16 μg/mL.