GKK1032B from endophytic Penicillium citrinum induces apoptosis of human osteosarcoma MG63 cells via caspase pathway

Chemical investigation of the culture extract of an endophytic Penicillium citrinum from Dendrobium officinale, afforded nine citrinin derivatives ( 1 – 9 ) and a peptide-polyketide hybrid GKK1032B ( 10 ). The structures of these compounds were determined on the basis of spectroscopic methods. The absolute configurations of 1 and 2 were determined for the first time by calculations of electronic circular dichroism (ECD) data. Among them, GKK1032B ( 10 ) showed significant cytotoxicity against human osteosarcoma cell line MG63 with an IC50 value of 3.49 μmol·L–1, and a primary mechanistic study revealed that it induced the apoptosis of MG63 cells via caspase pathway.