Chemical Composition and Antimicrobial Activity of the Essential Oil of Iris pallida Lam.

Essential oils from the fresh rhizomes and the naturally aged rhizomes of Iris pallida Lam.were analyed by GC-MS,respctively,and the relative contents of constituents were determined by area normalization method.The antimicrobial activity of the essential oil was evaluated against 3 fungi and 12 bacteria including 7 clinical isolated strains.The results show that:twenty-six volatile components were identified and determined in the oil of the fresh rhizomes,accounting for 92.09 % of the total area of the peak,and the main compounds of the oil were tetradecanoic acid(31.77 %),hexanoic acid(15.33 %),3-methyl-butanoic acid(12.20 %),pentanoic acid(9.29 %),heptanoic acid(7.91 %),3-methyl pentanoic acid(7.25 %),octanoic acid(2.44 %),2',4'-dihydroxy-3'-methylacetophenone(1.04 %).Forty-five volatile components were identified and determined in the oil of the naturally aged rhizomes,accounting for 85.63 % of the total area of the peak,and the main compounds of the oil were tetradecanoic acid(28.02 %),tetradecanoic acid,ethyl ester(10.42 %),9,12-octadecadienoic acid(7.67 %),dodecanoic acid(6.41 %),hexanoic acid(5.14 %),hexadecanoic acid(4.44 %),dodecanoic acid ethyl ester(4.09 %),linoleic acid ethyl ester(3.87 %),hexadecanoic acid ethyl ester(3.13 %),ethyl oleate(2.85 %),α-ionone,6-methyl-(1.39 %),and decanoic acid(1.31 %);the oil of the fresh rhizomes presented a broad antimicrobial spectrum,and the minimal inhibitory concentration(MIC)value was 0.25 g/L and the minimal bactericidal concentration(MBC)value was 0.35 g/L;the oil of the naturally aged rhizomes presented a broad antimicrobial spectrum,and had better antimicrobial activity against gram-positive bacteria,MIC value was 0.05 g/L and MBC value was 0.08 g/L.