Thesis (M.Sc.)--Chulalongkorn University, 2007

In this study, Pomelo peels, consist of albedo and flavedo from the cultivars Khao Taeng-gwa (KT), Khao Yai (KY), Khao Nam Pheung (KN) and Tong Dee (TD) were extracted and screened for free-radical scavenging, tyrosinase inhibition and UV absorption activities. The result indicated that methanolic crude extract of the KT albedo possessed strongest free-radical scavenging and tyrosinase inhibition activities and showed UV-A and UV-B absorption activity. The main of bioactive compound in KT peel was identified to be naringin, a flavanone glycoside. Efficient process to isolate high purity naringin from albedo was then explored. A simple liquid-liquid extaction (dichloromethane/water) coupled with crystallization gave 2.4 % (w/w) yield of naringin in >> 97 % purity. Moreover, naringin also found in albedo of KY, KN and TD cultivars with the high yield.