Apoptotic effect of eugenol in human colon cancer cell lines.
Cell Biol Int. 2010 Nov 2. Epub 2010 Nov 2. PMID: 21044050
Eugenol, a natural compound available in honey and various plants extracts including cloves and Magnoliae Flos, is exploited for various medicinal applications. Since most of the drugs used in the cancer are apoptotic inducers, the apoptotic effect and anticancer mechanism of eugenol were investigated against colon cancer cells. Antiproliferative effect was estimated using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay (MTT). Earlier events like mitochondrial membrane potential (MMP), thiol depletion and lipid layer break were measured by using flow cytometry. Apoptosis was evaluated using Propidium Iodide (PI) staining, Terminal deoxynucleotidyl transferase (TdT) mediated dUTP nick end labelling (TUNEL) assay and DNA fragmentation assay. MTT assay signified the antiproliferative nature of eugenol against the tested colon cancer cells. PI staining indicated increasing accumulation of cells at sub-G1 phase. It was 33.29± 4.93 and 37.84 ± 4.28 for HT-29 and HCT-15 after 48 h for eugenol treated cells. Eugenol treatment resulted in reduction of intracellular non-protein thiols and increase in the earlier lipid layer break. Further events like dissipation of MMP and generation of reactive oxygen species (ROS) wereaccompanied in the eugenol-induced apoptosis. Augmented ROS generation resulted in the DNA fragmentation of treated cells as shown by DNA fragmentation and TUNEL assay. Further activation of poly-adenosine diphosphate-ribose polymerase (PARP), p53 and caspase-3 were observed in the western blot analyses. Our results demonstrated molecular mechanism of eugenol-induced apoptosis in human colon cancer cells. This research will further enhance eugenol as a potential chemopreventive agent against colon cancer.