In vitro protective effects of plants frequently used traditionally in cancer prevention in Thai traditional medicine: An ethnopharmacological study.

Thai traditional medicine (TTM) has been used widely in cancer management in Thailand. Although several Thai medicinal plants were screened for pharmacological activities related to cancer treatment, such evidence still suffers from the lack of linking with TTM knowledge. To document knowledge and species used in cancer prevention in TTM and to preliminary investigate pharmacological activities related to the documented knowledge of twenty-six herbal drugs used in cancer/mareng prevention. Fieldwork gathering data on TTM concept and herbal medicines used in cancer prevention was performed with TTM practitioners across Thailand. Later, water and ethanol extracts from twenty-six herbal drugs mentioned as being used in cancer prevention were screened for their protective effect against tert-butyl hydroperoxide-induced cell death in HepG2 cells. Then active extracts were investigated for their effects on NQO1 activity, glutathione level, and safety in normal rat hepatocytes. The fieldwork helped in the development of TTM cancer prevention strategy and possible experimental models to test the pharmacological activities of selected medicinal plants. Fifteen plant extracts showed significant protective effect by restoring the cell viability to 40-59.3%, which were comparable or better than the positive control EGCG. Among them, ethanol extracts from S. rugata and T. laurifolia showed the most promising chemopreventive properties by significantly increased NQO1 activity, restored GSH level from oxidative damage, as well as showed non-toxic effect in normal rat hepatocytes. TTM knowledge in cancer prevention was documented and used in the planning of pharmacological experiment to study herbal medicines, especially in cancer, inflammation, and other chronic diseases. The proposed strategy should be applied to in vivo and clinical studies in order to further confirm the validity of such a strategy. Other traditional medical systems that use integrated approaches could also apply our strategy to develop evidence that supports a more rational uses in traditional medicine.