How to obtain UA and what’s challenges for application
UA is widely distributed as triterpene saponin aglycone or free acid in various medicinal plants as well as several fruits, such asLigustrum lucidum 33, Centella asiatica34, Lysimachia clethroides35, Crataegus pinnatifida 36and Malus domestica 37. However, its percentage varies from species to species due to related biosynthetic enzymes and metabolism 38. Currently, industrial production of UA mainly depends on extraction of natural plants. A variety of extraction methods have been developed to extract UA from different plants.