Anticancer effect of antioxidant-rich methanolic extract of Rauvolfia serpentina (L.) Benth. ex Kurz leaves in HepG2 and HeLa cells: A mechanistic insight

Rauvolfia serpentina (L.) Benth. ex Kurz is a pharmaceutically, and agriculturally important medicinal plant traditionally used against snake and insect bites, dysentery, abdominal pain, fever, and insanity. However, no detailed study has been done on anticancer potency of crude leaf extract of Rauvolfia serpentina. Therefore, we investigated the anticancer activity of methanolic extract of Rauvolfia serpentina leaf (MERSL) in human hepatocarcinoma HepG2 and cervical cancer HeLa cells along with its antioxidant capacity. GC-MS analysis revealed the presence of many anticancer phytochemicals including campesterol, stigmasterol, beta-sitosterol, alpha-amyrin, lupeol, phytol, and D-pinitol. The antioxidant activity of MERSL was confirmed by DPPH (IC50 = 106.16 mu g/ml), ABTS (IC50 = 146.67 mu g/ml), FRAP (IC50 = 1.4 mg/ml), and total antioxidant capacity assay in vitro, and reduction of H2O2-induced ROS in noncancer fibroblast F111 cells. Crystal violet assay showed that MERSL reduced cell viability in HepG(2) (IC50 = 274.12 mu g/ml) and HeLa (IC50 = 231.33 mu g/ml) at 24 h, but not in F111 cells at these IC50 concentrations. Further, wound healing and clonogenic assays confirmed anticancer activity, which resulted in decreased cell migration and revival capacity in HepG2 and HeLa cells. Apoptotic changes were visualized by acridine orange-ethidium bromide and DAPI staining using fluorescence and confocal microscopy. Also, comet assay indicated DNA damage. An increase in intracellular ROS, calcium influx, reduction of mitochondrial mass and membrane potential, and cell cycle arrest, established by flow cytometry and fluorimetry, highlighted the possible underlying mechanism of cell death by MERSL in HepG2 and HeLa cells. Therefore, this study evidenced that Rauvolfia serpentina leaves could be an encouraging pharmacological application for developing anticancer strategies.