ESSENTIAL OIL EXTRACTED FROM PLECTRANTHUS AMBOINICUS INDUCES APOPTOSIS IN THE LUNG CANCER CELLS VIA MITOCHONDRIAL PATHWAY

Abstract

The use of medicinal plants in the form of extracts and oils dates back to pre-historic times. The aim of the study was to determine the effect of Essential oil (EO) extracted from leaves of Plectranthus amboinicus on lung cancer cell line, A549. MTT assay was performed to check the efficacy of Essential oil to induce death in cancerous A549 cells and normal HEK293 cells. Acridine Orange/Ethidium Bromide staining, Hoechst staining and DNA fragmentation assays were used to confirm the apoptosis inducing ability of EO on A549 cells. RT-PCR and western blotting was performed to check the expression of pro- and anti-apoptotic factors. Calorimetric assay was done to check caspase-3 and caspase-9 activities. Essential oil at lower concentrations was found to induce cell death selectively in the lung cancer cells (IC50 = 10.74 µg/mL). The transcriptional expression studies of the pro-apoptotic Bax and anti-apoptotic Bcl-2; and the western blot analysis of pro-apoptotic BAK and BAD showed that EO upregulated the expression of pro-apoptotic factors and down regulated the expression of anti-apoptotic factors in A549 cells. Caspase-9 and 3 activities were found to be upregulated in the calorimetric studies. The down regulation of anti-apoptotic factors and upregulation of pro-apoptotic factors show that the Essential oil induced apoptosis in the lung cancer cells via the intrinsic or the mitochondrial pathway.