STUDIES ON FREE RADICAL SCAVENGING ACTIVITIES OF EXTRACTS FROM LEAVES OF SOME SUBTROPICAL ESSENTIAL OIL TREES

A DPPHmicroplate assay was made to determine the free radical scavenging activity of80% methanol extracts from leaves of some subtropical essential oil trees.Results revealed that all extracts from trees have different free radical scavenging capacities.Their free radical scavenging capacities increased with the raising of concentration and incubation time at 37 ℃.Of all trees,Pistasia chinensis Bunge,Liquidambar formosana Hance,Myrica rubra(Lour.) Sieb.et Zucc.,Rosa banksiae Ait. and R.cymosa Tratt. have the strongest free radical scavenging capacity with a DPPH decreasing rate of 90.6%,85.7%,79.1%,62.5% and 61.3%,respectively at a concentration of 0.5 mg/mL after incubated for 20 min.Phoebe sheareri(Hemsl.) Gamble,Pinus elliottii Engelm.,Lindera praecox Bl.,L.erythrocarpa Makino,R.chinensis Jacq.,Juniperus formosana Hayata and Litsea coreana Levl.var.sinensis(Allen) Yang et P.H.Huang have also moderate free radical decreasing ratio under the same conditions.