Evaluation of essential oil composition and antioxidant capacity of hydromethanolic extracts of Tetraclinis articulata,depending on location and seasonal variations

This work describes the seasonal and geographical variation in essential oils composition,the in vitro lipid peroxidation inhibitions,the anti-radical activities and total phenolic contents of two aqueous methanol (methanol: water,80:20 and 50:50 v/v) and essential oils fractions of aromatic wild plant,tetraclinis articulata (vahl) masters,grown in two arboreta in the north east tunisia. chemical composition of the essential oils was evaluated by gc/ms and gc/fid. the inhibition of lipid peroxidation and dpph radical scavenging ability were studied to evaluate the antioxidant activity for six extracts of tetraclinis articulata. the results show that essential oil content was not affected by geographical origin and was significantly affected by season (p≤ 0.05). the essential oil yields ranged from 0.10% to 0.26%,the maximum amount was observed during winter (january) and the minimum was obtained in spring (may). gc/ms analysis revealed 29 constituents in this plant. for both geographical origins (korbous and jbel abderrahmen) and four season periods (january; april; may and november 2010),highly significant differences were observed for oil compositions (p≤ 0.05). the main compounds identified in the leaves of this plant were a-pinene (26.3 -36.6%),bornyl acetate (19.0 - 25.4%),camphor (5.5 - 15.3%),and limonene (5.3 - 8.9%). others representative components were detected such as β-myrcene (3.9 - 6.6%),borneol(3.0 - 6.8%) and caryophyllene (0.2 - 5.1%). for the antioxidant data,the methanol: water (50:50 v/v) fraction of the january harvest exhibited the highest dpph radical scavenging activity,and exerted the highest percentage inhibition of the induced autoxidation of methyl linoleate. the total phenolic content of various extracts was in the range of 17.7±0.7 to 30.1±1.0 eq. gallic acid/g. this study demonstrated that inhibition of lipid peroxidation and the dpph radical scavenging ability of tetraclinis articulata leaf are correlated with the amount of phenolic constituents.