Methyl protodioscin from Polygonatum sibiricum inhibits cervical cancer through cell cycle arrest and apoptosis induction

Methyl protodioscin (MPD) is a steroid saponin which has been well known for its pharmacological properties. Herein, we evaluated the anti-cancer activity of MPD for proliferation inhibition and apoptosis induction in Hela cells. MPD was purified from the rhizoma of Polygonatum sibiricum primarily and identified by HPLC, UPLC-TOF-MS/MS and NMR analysis, respectively. Results showed that MPD repressed cell proliferation at IC50 of 18.49 μM, altered cell morphology, arrested the cell cycle in G2/M phase, facilitated the generation of intracellular ROS and led to cell apoptosis in a concentration-dependent manner. Furthermore, MPD treatment promoted death receptor pathway and mitochondrial pathway efficiently. The inhibition of Caspase-8 and Caspase-9 proteins in these pathways abolished the apoptosis significantly, further demonstrated the mechanism of MPD-induced apoptosis. These findings offer novel information that MPD may be considered as a possible natural anti-cancerous agent in the form of functional foods or medicinal products.