The six Dioscorea species, D. brevipetiolata, D. bulbifera, D. depauperata (Dd), D. glabra (Dg), D. pyrifolia and D. hamiltonii were analyzed for phytochemicals, toxicity in PBMCs, and biological activity in two cancer cell lines by MTT and comet assays, and pesticide efficiency. Via GC-MS, lidocaine was found to be the predominant compound in two of the studied species. To confirm the systematics, lidocaine was also found in lower amounts in 11 species. The MTT assay showed no toxicity in all six of the studied species. The comet assay showed the key result that the ethanol extracts of Dd and Dg violently broke DNA into pieces. Biological activity of these two species' extracts showed toxicity on HepG2 and no effects on HCT-116. The water extracts of Dd and Dg, applied to Brassica chinensis showed high efficiency as a bioprotectant. In summary, lidocaine seems to be the predominant identifying compound of the genus Dioscorea in Thailand, which is useful in systematics. At least the two species, Dd and Dg, may be used for human hepatocyte cancer treatment and as an alternative pesticide for economically important vegetables. Dioscorea species containing lidocaine or extracted lidocaine have promise for natural product creation.
Keywords: Brassica chinensis; Dioscorea depauperata; Dioscorea glabra; HCT-116; HepG2; human hepatocyte cancer; insect bioprotectant efficiency; lidocaine.