Apoptosis Inducing Effects of Thymus Linearis Methanolic Extract in HCT-116 Cells and LC-MS Chemical Profiling of Its Active Constituents

Background: Cancer is one of the major problems at present, to which vast research is being dedicated to find an effective remedy. Medicinal plants are endowed with numerous molecules that could be effective in multiple diseases including cancer. Thymus linearis, being rich in phenols, terpenoid, and flavonoids have the potential to provide anti-cancer entities. Methods: The extracts of Thymus linearis were investigated for in vitro anticancer activity using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay on a panel of cancer cell lines. The cellular and nuclear morphology was studied using microscopic techniques. Agarose gel electrophoresis was used for DNA fragmentation analysis. Protein expression was determined by western blotting. LC-MS was used for phytochemical identification. Results: Among all the extracts, Thymus linearis methanolic (TLM) extract was found to exhibit antiproliferative activity on cell lines to varying degrees. TLM was found to be most potent against HCT-116 with an IC50 of 158μg/ml after 48hrs treatment while being nontoxic to HEK-293 and FR-2 cells under similar concentrations. TLM decreased clonogenic potential of HCT-116 cells. It induced cell shrinkage, membrane blebbing and nuclear fragmentation characteristic of apoptotic in a dose dependent manner in HCT-116 cells. Prominent internucleosomal DNA cleavage was observed in HCT-116 cells after 48hrs TLM treatment. Western blot analysis revealed the up regulation of expression of Bax, caspases 9 and caspases 3 and downregulation of Bcl-2 proteins. The LC-MS data revealed the presence of Salvianolic acid H, Synparvolide C, Thymuside A and Jasmonic acid; 12-Hydroxy, O-β-D-glucopyranoside and polyphenolic flavonoids to which antiproliferative activity can be attributed. Conclusion: The results suggest that Thymus linearis methanolic extract could be valuable source of anti-cancer agents.