Camboginol and Morelloflavone from Garcinia dulcis (Roxb.) Kurz Flower Extract Promote Autophagic Cell Death against Human Glioblastoma Cells through Endoplasmic Reticulum Stress.

Garcinia dulcis is a tropical plant native to Southeast Asia that is traditionally used as a folk remedy to cure several pathological symptoms. Camboginol and morelloflavone have been revealed by previous studies as the principal bioactive compounds from the flower extract of G. dulcis. The disease-preventing properties of camboginol or morelloflavone, including anti-cancer, from various parts of G. dulcis have been revealed by recent studies. Glioblastoma is the aggressive malignant stage of brain cancer and suffers from chemotherapeutic resistance. This study aimed to test the anti-cancer effect of G. dulcis flower extract against the proliferation of A172 human glioblastoma cells. The extract had cytotoxic activity and promoted cell cycle arrest at the S and G2/M phases. Autophagic cell death was promoted by cytotoxic concentrations of the extract, as observed by enhancing autophagic flux and the expression of autophagic markers. Autophagic cell death induced by the extract might be associated with endoplasmic reticulum (ER) stress. Conclusively, it was indicated by this study that the extract from the flower of G. dulcis had a protective effect against the proliferation of A172 human glioblastoma cells through the induction of ER stress-mediated cytotoxic autophagy.