Evaluation of dose and time-dependent effects of methyl butyrate, a major essential oil component, on cancer cell survival in vitro.

Aroma has been used as a complementary or adjunct therapy to the main line of treatment since time immemorial. Essential oils (EOs) extracted from various plant parts are known to stimulate brain function and are, thus, used as a therapy to manage and alleviate diseases. Methyl butyrate (MB), an ester with a characteristic fruity smell, is reported to be one of the principal constituents of naturally occurring EOs of many plants. The current study elucidates the efficacy of MB in inhibiting growth and viability of human lung carcinoma (A549 and NCI-H23) and breast carcinoma (MCF-7) cells. The mechanism of MB-induced cytotoxicity was determined by acridine orange-ethidium bromide (AO-EtBr) staining. Intracellular ROS generation was determined using the dichloro-dihydro-fluorescein-diacetate (DCFH-DA) dye. The findings revealed that MB, being volatile, exhibited considerable cytotoxicity in all three cell lines at a concentration of 52 mM without being added directly to the medium. Gel electrophoresis of isolated DNA from treated cells showed the absence of fragmentation, the hallmark of apoptosis. MB appeared to induce necrosis in the studied cancer cell lines. The IC50 value of MB against A549 cells was found to be 49 mM using MTT assay and necrosis/necroptosis was found to be the major mechanism responsible for cell death of MB-treated A549 cells. MB induced G2/M phase arrest in the cell cycle of treated A549 cells vis-à-vis untreated controls. Few studies dealing with the beneficial effects of volatile components of EOs on stress and anxiety management in patients with critical illnesses have been reported and even fewer studies have explored their therapeutic potential in cancer. The present study is the first of its kind to report the cytotoxic and anticancer effects of MB, a major bioactive component of many naturally occurring EOs and warrants further investigation and validation in animal as well as other cell culture models of cancer.