Antibacterial Polyketides from the Deep-Sea Cold-Seep-Derived Fungus sp. CS-258.

Thirty-two fungal polyketide derivatives, including eleven new compounds, namely (3,5')-5-hydroxytalaroflavone (), talaroisochromenols A-C (, , and ), (8,9,10a)-5-hydroxyaltenuene (), (8,9,10a)-5-hydroxyaltenuene (), (8,9,10a)-5-hydroxyaltenuene (), nemanecins D and E ( and ), 2,5-dimethyl-8-iodochromone (), and talarofurolactone A (), together with one new naturally occurring but previously synthesized metabolite, 6-hydroxy-4-methoxycoumarin (), were isolated and identified from the deep-sea cold-seep-derived fungus sp. CS-258. Among them, racemic ((±)-) or epimeric (-, , and ) mixtures were successfully separated by chiral or gradient elution HPLC. Meanwhile, compound represents a rarely reported naturally occurring iodinated compound. Their planar structures as well as absolute configurations were determined by extensive analysis via NMR, MS, single-crystal X-ray diffraction, Mosher's method, and ECD or NMR calculation (with DP4 probability analysis). Possible biosynthetic routes of some isolated compounds, which are related to chromone or isochromone biosynthetic pathways, were put forward. The biological analysis results revealed that compounds , -, , , and showed broad-spectrum antibacterial activities against several human and aquatic pathogens with MIC ranges of 0.5-64 μg/mL.