Cytotoxic and pro-apoptotic activities of leaf extract of Croton bonplandianus Baill. against lung cancer cell line A549.

The acetone extract (AcE) of the Croton bonplandianus Baill., an exotic weed of the Euphorbiaceae family was studied for cytotoxicity, apoptosis, cell cycle arrest in A549 cell line and antioxidant capacities using MTT assay, acridine orange/ethidium bromide (AO/EB staining), cell cycle analysis and DPPH radical scavenging assay respectively. Based on the cytotoxic activity, the extract was tested for the apoptotic effect using AO/EB and Hoechst 33258 staining. The apoptosis was characterized by chromatin condensation and DNA fragmentation. Further, to determine the stage of cell death, cell cycle analysis was performed by flow cytometry and AcE was found to arrest G2/M phase in a dose dependent manner. The number of cells in G2/M phase increases with concurrent accumulation of cells in sub G₀/G₁phase indicates the induction of apoptosis at G2M phase. The free radical scavenging activity of the AcE against DPPH was considerably significant. The cytotoxic, apoptotic and antioxidant effect of the AcE could be well correlated with the presence of potent free radical scavenging secondary metabolites such as phenols (43 ± 0.05 µg/mL), flavonoids (3.5 ± 0.07 µg/mL) and tannin (0.36 ± 0.1 µg/mL). Our study has shown that A549 cells were more sensitive to AcE with an IC₅₀ of 15.68 ± 0.006 µg/mL compared to the standard drug 2.20 ± 0.008 µg/mL (cisplatin). The results suggest that Croton bonplandianus could serve as a potential source of alternative therapeutic agent for treating cancer. Further research is required to isolate the active principle compound and determination of its anticancer property.