Mollicellins O⁻R, Four New Depsidones Isolated from the Endophytic Fungus Chaetomium sp. Eef-10.

Four new depsidones, mollicellins O⁻R (compounds 1 ⁻ 4 ), along with three known compounds 5 ⁻ 7 , were isolated from cultures of the fungus Chaetomium sp. Eef-10, an endophyte isolated from Eucalyptus exserta . The structures of the new compounds were elucidated by analysis of the 1D and 2D NMR and HR-ESI-MS spectra. The known compounds were identified by comparison of their spectral data with published values. Compounds 1 ⁻ 7 were evaluated for antibacterial activities against Staphylococcus aureus (sensitive and resistant strains), Escherichia coli , Agrobacterium tumefaciens , Salmonella typhimurium , Pseudomonas lachrymans , Ralstonia solanacearum , Xanthomonas vesicatoria and cytotoxic activities against two human cancer cell lines (HepG2 and Hela). Mollicellin H ( 6 ) displayed best antibacterial activity, with IC50 values of 5.14 µg/mL against S. aureus ATCC29213 and 6.21 µg/mL against S. aureus N50, MRSA, respectively. Mollicellin O ( 1 ) and mollicellin I ( 7 ) also exhibited antibacterial activities against S. aureus ATCC29213 and S. aureus N50. Mollicellin G ( 5 ) was active against both two human cancer cell lines, with IC50 values of 19.64 and 13.97 µg/mL while compounds 6 and 7 only showed cytotoxic activity against one cell line. In addition, mollicellin O ( 1 ) showed antioxidant activity based on DPPH radical scavenging, with an IC50 value of 71.92 µg/mL.