Glutathione S-Transferase and β-Glucuronidase Enzymes Inhibitory and Cytotoxic Activities of Ethanolic and Methanolic Extracts of Sri Lankan Finger Millet (Eleusine coracana (L.) Gaertn.) Varieties

Abstract

Background: The adverse side effects of cancer management and the increasing rate of mortality associated with cancers create a necessity to discover alternative strategies in cancer management and new anticancer agents especially derived from plant materials. Aims: This study was focused on evaluating glutathione S-transferase and β-glucuronidase enzymes inhibitory activities and cytotoxicities against human lung and breast cancer cell lines of ethanolic and methanolic extracts of Ravi, Rawana and Oshadha finger millet varieties in view of the anticancer potential.  Methodology: Flours of whole grains of the finger millet varieties were extracted with ethanol and methanol separately. Glutathione S-transferase and β-glucuronidase enzymes inhibitory activities of the extracts were evaluated using standard methods. Cytotoxic effects on brine shrimps were evaluated as a preliminary assessment of toxicity. Growth inhibitory properties were studied on human lung and breast cancer cell lines and mouse embryo normal cell line using the MTT assay. Results: The findings revealed dose-dependent glutathione S-transferase and β-glucuronidase enzymes inhibitory activities of ethanolic and methanolic extracts of Ravi, Rawana and Oshadha finger millet varieties. All extracts were non-cytotoxic upon normal cells and showed growth inhibitory properties upon human breast cancer cells. Methanolic extract of Oshadha showed the highest glutathione S-transferase (IC50 value: 236.18 µg/mL) and β-glucuronidase (IC50 value: 125.31 µg/mL) inhibitory activities and highest cytotoxicity upon human breast cancer cells. However, all extracts did not qualify as promising sources of cytotoxic agents against human lung cancer cells at the tested concentrations. Conclusion: The findings of the present study suggested the potential of ethanolic and methanolic extracts of Ravi, Rawana and Oshadha finger millet varieties to enhance the efficacy of chemotherapy and to prevent and manage liver, colon and breast cancers. The specific compounds which are responsible for each activity will be studied in future.