RÉSUMÉ
Objective To observe the free radical scavenging action of volatile oil from Piper longum L.growing in Hainan Province and to explore the relationship of the action with molecular structure.Methods 1,1-Diphenyl-2-picrylhydrazyl radical(DPPH) method was used to determine the scavenging action.The components of volatile oil were analyzed by GC-MS,and their molecular structures were identified by databank.Results(1)The volatile oil from Piper longum L.had scavenging actions on free radicals in a concentration-dependent manner.(2)Forty one compounds were found in volatile oil from Piper longum L.growing in Hainan Province,in which the amount of carbon-carbon double bond(C=C) was in predomination.Conclusion Carbon-carbon double bond(C=C)is the essential functional group for free radical scavenging action of volatile oil from Piper longum L.