Pituranthos tortuosus Essential Oil from Libya: Season Effect on the Composition and Antioxidant Activity

Pituranthos tortuosus has multi-local traditional applications, production of aroma, in culinary processes, killing insects and as a remedy for diabetes, infectious diseases, dyspepsia, inflammation, fever and hepatitis. The essential oil antioxidant quality and composition of the dried aerial part of P. tortuosus collected at two successive seasons (spring and summer) were investigated. Essential oils were obtained by hydrodistilla- tion, physically evaluated and analyzed by the GC-MS. The ability of the oil-batches to restore the glutathione level in the alloxan-induced diabetic rats was used to assess the antioxidant quality. A total of twenty-eight com- pounds representing 98.65 % of the 0.8 % oil-yields and nineteen compounds representing 98.39 % of the 0.3 % oil-yields were identified in the summer and spring oil-batches, respectively. The oxygenated (38.47 %) and non-oxygenated (36.31 %) monoterpenes were accumulated in the spring oil-batch. In contrast, sesquiterpenes were accumulated in the summer oil-batch which may reflects the effect of monoterpenes emission due to summer temperature and the different biosynthetic preferability of the plant during summer and spring seasons. 1,8-cineole (13.43 %), 9-epi-caryophyllene (11.62 %) and alpha-cadinol (21.51 %) were the major constituents of summer oil-batch, while alpha-thujene (21.22 %) and linalool (27.98 %) were major components of spring oil- batch. The glutathione level was restored significantly (P< 0.05) in the animal treated with summer (33.6 %) and spring (32.8 %) oil-batches compared to the alloxan diabetic animals (21.3 %). In conclusion, major chemical changes were recognized in the summer and spring volatile oil-batches evidenced by the variations in the percentages of the monoterpenes and sesquiterpenes in these oil-batches which affect the antioxidant quality of the oils.