Free radical scavenging activity of extracts from Thai plants in Guttiferae and Schisandraceae families

Abstract

Five Thai plants from the Guttiferae (Hypericum hookerianum Wight & Arn, Garcinia speciosa Wall, Garcinia xanthochymus Hook f. ex. T. Anderson, Cratoxylum formosum ssp. pruniflorum (Kurz) Gogel, and Calophyllum polyanthum Wall ex Choisy) and one from the Schisandraceae (Schisandra verruculosa} were extracted by methanol and chloroform. The extracts were screened for free radical scavenging activity using the DPPH assay. All extracts showed a dose-dependent antioxidant activity. The most potent with the lowest IC50 values were observed in the methanol extracts from the wood of G. speciosa, which were 2.5- and 5.3-fold more potent than the two standard antioxidants, ascorbic acid and α-tocopherol, respectively. Free radical scavenging activities ranging from moderate to high were observed in both methanol and chloroform extracts from H. hookerianum, C. formosum ssp. pruniflorum, G. xanthochymus, S. verruculosa and C. polyanthum. The information from this study can explain the traditional use and the further development of these extracts into new pharmaceuticals. © 2005 Taylor & Francis Ltd.