Bioactive Compounds and Biological Activities of Edible Yam (Dioscorea sp.) in Thailand

Yam (Dioscorea spp.) is one of the essential crops used as a starch source for human consumption, especially in Africa, Asia, and the South Pacific. Some cultivars have biofunctional properties such as antioxidant, antimicrobial, antifungal, antimutagenic, hypoglycemic, and immunomodulatory effects. However, using Dioscorea spp. as food and medicinal plants in Thailand is limited since yam is not cultivated in Thailand. This study reviewed the bioactive compounds found in Thai yams, i.e., D. hispida Dennst., D. esculenta Burk., and D. alata L. used as foods, and D. bulbifera L, D. birmanica Prain & Burkill, and D. membranacea commonly used in traditional Thai medicines. The habitats and distribution of Thai yam and nutritional benefits (starch, protein, polysaccharide, and glycoprotein) and secondary metabolites (steroidal saponins, allantoin, polyphenols, and alkaloids) were discussed. This study also addressed the alterations of some bioactive compounds in yam during food production. Moreover, knowledge about nutritive and medicinal characteristics could help determine appropriate measures in Thai yam classification and selections for future use by applying functional genes to aid the selection of multispecies plant populations from their natural habitats with the desired traits and explore the genetic potential for crop improvement and biodiversity management for sustainable utilization of Thai yam.