Antiproliferative activity of chrysin (5, 7-dihydroxyflavone) from Indigofera tinctoria on human epidermoid carcinoma (A431) cells

Introduction: Indigofera tinctoria widely used in Indian and Chinese medicinal system to cure various diseases. Based on the ethnomedicinal value of this plant, the present investigation was aimed to isolate the bioactive compound from Indigofera tinctoria and evaluate the antiproliferative activity against human epidermoid carcinoma (A431) cells. Methods: Chrysin (CH) was purified from the chloroform extract of I. tinctoria leaves by silica gel column chromatography and its antiproliferative effect against A431 cells was evaluated by MTT assay. Apoptotic effects were analysed by DNA fragmentation, nucleic acid content and acridine orange/ethidium bromide staining. Cell cycle arrest was analysed by flow cytometry. The apoptotic markers such as cytochrome c, caspase 9, caspase 3 and inhibitor of caspase activated DNase (ICAD) expression were analysed by western blot. Results: MTT assay results revealed that the CH has inhibited the proliferation of A431 cells with IC50 value of 23.52 mu g/mL and exhibited potent cytotoxicity; where as there is no promising toxic effect against normal HaCaT cells. DNA fragmentation analysis indicated that the CH treated A431 cells displayed the fragmented DNA. Further, CH induced remarkable cell death through apoptosis (87.65 +/- 1.80%) and arrested the cell cycle at Sub G(1) phase. Moreover, the CH could enhance the expression of cytochrome c, caspase 9, caspase 3 and inhibit the ICAD in a dose dependent manner. Conclusion: The present investigation concluded that the CH purified from I. tinctoria has potentially inhibited the proliferation of human epidermoid carcinoma (A431) cells and induce the apoptosis through caspase dependent manner.