GKK1032B from endophytic Penicillium citrinum induces the apoptosis of human osteosarcoma MG63 cells through caspase pathway activation

Abstract: Chemical investigation of the culture extract of an endophytic Penicillium citrinum from Dendrobium officinale, afforded nine citrinin derivatives ( 1 – 9 ) and one peptide-polyketide hybrid GKK1032B ( 10 ). The structures of these compounds were determined by spectroscopic methods. The absolute configurations of 1 and 2 were determined for the first time by calculation 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 activation.