Change of secondary metabolites in leaves of Ginkgo biloba L. in response to UV-B induction

A novel treatment by introducing ultraviolet-B (UV-B) radiation to Ginkgo biloba leaves was investigated for the first time to enrich their health-related compounds. This study was aimed to quantify and identify secondary metabolites involved in the response to UV-B in freshly collected Ginkgo leaves. In this study, leaves were put in the inducing device with or without UV-B radiation of 82.90 mu W cm(-2) intensity. After radiation, methanol extractable compounds were quantified using high performance liquid chromatography (HPLC) by measuring change of flavonoids concentration. Leaves age and radiation time effects were investigated. Younger leaves (April) and moderate radiation time (120 min) showed distinct increase of flavonoids after UV-B screening (with an increase up to 56%). Furthermore, compound Gb1 which are thought to trigger an array of defensive response named 3-(4'-hydroxyphenyl)-1-thiol-2-propylene showed a significant enhancement in UV-B treated leaves. Our findings showed that UV-B radiation time-, leaf age-, phytochemical-specific were key factors that influenced the change of secondary metabolism. UV-B would be a novel and feasible processing method to increase the health-related compounds of fresh collected products. Industrial relevance: This study generally aims to provide a convenience and feasible approach to enhance the phytochemical compounds in fresh nature products exampled by an excellent herb plant Ginkgo biloba L where showed a significant effect. Featured by the shorter period required, the easier procedures to carry out as well as the fewer experimental costs, short-term and moderate UV-B radiation can be applied to either targeted postharvest treatment of agriculture or pretreatment of processing industry to stimulate the production of health-related compounds in natural fresh product. In this regard, our study aimed to provide an innovation method for food and pharmaceutical technology. (C) 2010 Elsevier Ltd. All rights reserved.