Studies on Free Radical Scavenging Activities of Extracts from Leaves of Some Subtropical Oil Trees

A DPPH-Microplate assay were made to determine the free radical scavenging activity of the 80% methanol extracts from the leaves of subtropical oil trees. The results revealed that all trees have different free radical scavenging capacities, and as the raising of concentration and the prolonging of incubation time at 37℃, their free radical scavenging capacities increased. Of all trees, Acer ginnala Maxim. ssp. theiferum (Fang) Fang, Hamamelis mollis Oliv., Pistasia chinensis Bunge, Camellia sinensis (L.) O.Ktze., A. buergerianum Miq.,Koelreuteria bipinnata Franch. var. integrifiola (Morr.) T.,Alchornea davidii Franch.,Cornus alba L.,Loropetalum chinense R.Br.,Acer elegantulum Fang et Chiu,Glochidion puberum (L.) Hutch.,Toxicodendron sylvestre O.Kuntze,Camellia oleifera Abel.,Fagus engleriana Seem., Sapium sebiferum (L.) Roxb., Koelreuteria paniculata Laxm. and Camellia japonica L. have the strongest free radical scavenging capacity. The extracts at a concentration that equals to 0.5 mg leaves per milliliter, after incubated for 20 minutes they can reach a DPPH decrease rate of 96.7%, 93.2%, 90.65%, 87.5%, 86.4%, 85.0%, 84.3%, 82.1%, 80.8%, 77.1%, 74.5%, 72.5%, 72.3%, 68.7%, 63.8%, 62.0% and 61.7% respectively.