A new trithiodiketopiperazine derivative, adametizine C (1), and five new alkane derivatives (7-11), were isolated from the mangrove sediment-derived fungus Penicillium ludwigii SCSIO 41408, together with five known dithiodiketopiperazine derivatives (2-6). Their structures were elucidated on the basis of spectroscopic analysis, and the absolute configuration of 1 was determined by X-ray crystallographic analysis. In a variety of bioactivity screening, 1-5 exhibited some selective antifungal or antibacterial activities. Compounds 1-3 showed cytotoxicity against prostate cancer cell line 22Rv1 with half maximal inhibitory concentration (IC50) values of 13.0-13.9 μM; moreover, 3 showed obvious activity against another prostate cancer PC-3 cells with an IC50 value of 5.1 μM. Further experiments revealed that 3 could significantly reduce PC-3 cells colony formation and induce apoptosis in a dose-dependent manner. Several compounds also exhibited obvious inhibitory activities of lipopolysaccharide-induced nuclear factor-κB with IC50 values range from 8.2 to 21.5 μM, and 1, 5, and 9 were further evaluated for their effects on receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis. Adametizine C (1), with the strongest inhibitory activity against RANKL-induced osteoclast differentiation in bone marrow macrophage cells with 10 μM, was suggested to be the promising lead compound for the treatment of osteoclast-related diseases.
Keywords: NF-κB; PC-3; mangrove-sediment-derived fungus; osteoclast differentiation; penicillium ludwigii; thiodiketopiperazines.
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