Abstract: In order to study the chemical composition and medical efficacy of Tea tree oil produced in China,the essential oil of Melaleuca ahemifolia leaves and shoots from Sichuan was extracted by water vapor distillation,analyzed by GC/MS technology,and the antimicrobial activity against Propionibacterium acnes was analyzed by agar diffusion method.The results showed that more than 100 kinds of ingredients were identified and determined in the tea tree oil,including 44 kinds components more than 0.1%,accounted for 95.75% of total area of the peak,and the major components were terpene(60.14%) and terpene alcohol(34.18%).The terpinen-4-ol(24.43%) was the highest.Antimicrobial activity of tea tree oils was observed against Propionibacterium acnes,and the inhibition increased with concentration of oil increase.Having in account the important antimicrobial properties observed in present work,we consider that teatree oil might be useful on pharmaceutical as natural antibiotic,themonoterpene,sesquiterpene and Terpinen-4-ol may be important compositions.

Key words: tea tree oil, propionibacterium acnes, chemical composition, antimicrobial activity