Oroxylum indicum Vent Root Bark Extract Inhibits the Proliferation of Cancer Cells and Induce Apoptotic Cell Death

Abstract

Oroxylum indicum Vent is a medium-sized deciduous tree that belongs to the family Bignoniaceae. The roots of this tree are used as one of the ten ingredients to prepare the Dasamula formulation in the Ayurvedic system of medicine in India. Although traditional uses are attributed to the medicinal plant, there are limited scientific data on its potential. The present study thus analyzed the cytotoxic and apoptotic potential of the plant against different cancer cells. MTT assay was used to determine cytotoxicity using HeLa, HCT 15, and MDA-MB-231 cells, with the IC50 values, revealed at concentrations of 92.43, 133.0, and 112.84 µg/mL respectively. However, the extract was less toxic to non-cancer cells. HeLa cells further treated with OIM were subjected to flow cytometric analysis for studying the cell cycle stages. When untreated cells at G1 phase were found at a relative percentage of 71.9%, it increased to 79.3 and 86% with OIM treatment at concentrations of 50 and 100 µg/mL; cells in the S phase decreased from 10.3 to 8.2 and 7.5%, concluding the arrest of the cell cycle at G1 phase. With further study of apoptotic morphology with dual acridine orange–ethidium bromide staining and Annexin–Hoechst staining, cells at early and late apoptotic stages were observed with OIM treatment at 100 µg/mL concentration. Although such effects were noticed with OIM treatment, it could not be concluded that the extract had remarkable anti-proliferative effects, since the small changes noticed in cell cycle arrest and apoptotic induction were attained at a high concentration of OIM 100 µg/mL. The biological activities of plants and their extracts are attributed to the presence of multifarious compounds present in them. LC-MS Q-TOF analysis confirmed the presence of biochanin A and baicalein in OIM. HPLC-based quantification of baicalein and chrysin was shown to be 3.36 and 1.11 mg/gram dry weight. To conclude, the above results suggest that the root bark of O. indicum has a broad spectrum of biological activities, including anticancer and apoptotic properties.