An ethnobotanical study of the genus Smilax in Thailand and its botanical authentication for Hua-khao-yen crude drugs

The first ethnobotanical work of the genus Smilax in Thailand was carried out to investigate the medicinal use of the Smilax species by folk healers, using the semi-structured interview, questionnaire survey, and literature review. Three quantitative indices were calculated, i.e. the Use Value (UV), the Relative Frequency Citation (RFC), and the Informant Agreement Ratio (IAR). Eleven species were recorded. Three of which, i.e. S. bracteata, S. hemsleyana, and S. leucophylla, are new records as medicinal species in Thailand. The genus has the potential use for the treatment of the genitourinary illnesses (IAR=1.00) and the neoplasms (IAR=0.71). Smilax glabra was the most used species with UVs=0.67, RFC=0.39. The results indicate the species being threatened due to over harvesting from the natural habitat. Furthermore, this study shows that the semi-structured interview coupled with the questionnaire survey is useful to gather the ethnobotanical data of a specific plant group. Botanical authentication of the commercial crude drugs based on chromatographic fingerprinting and macroscopic characters was carried out to verify the botanical identity of the homonym Hua-khao-yen crude drugs. Smilax glabra and Premna herbacea (Lamiaceae) were authenticated as the source of Hua-khao-yen-nuea and the Hua-khao-yen tai crude drugs, respectively.