Chaepseubakerins A-J, ten undescribed cytotoxic [11]-chaetoglobosins from an endophytic fungus Pseudeurotium bakeri

Ten previously unreported [11]-chaetoglobosins, chaepseubakerins A-J (1-10), were characterized from the solid rice-based culture of Pseudeurotium bakeri P1-1-1, an endophyte harbored in the roots of Macrocoma tenue subsp. sullivantii Vitt. (Orthotrichaceae). Their structures were determined by spectroscopic analysis, single -crystal X-ray diffraction (Cu K alpha radiation), and chemical methods. Chaepseubakerin A (1) exhibited signifi-cant cytotoxic effects against seven human cancer cell lines, A549, A427, HCT116, HT-29, HeLa, HepG2, and MCF-7, with IC50 values of 2.9, 3.0, 4.0, 4.4, 7.1, 6.7, and 8.9 mu M, respectively. Mechanistically, 1 induced G2/M cell cycle arrest and apoptosis in A549, Hela, and HCT116 cells in a dose dependent manner.