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Abstract SUMMARY The essential oils of lemongrass, geranium, french basil, coriander, spearmint, peppermint and neroli bigarade were obtained by steam distillation. 1- The physical properties (specific garvity at 15°C, refractive index at 200e, optical rotation and solubility in alcohol) of each oil were as follow: Lemongrass oil: 0.8534, 1.4883, -0.11 ° and soluble in (0.6-1.1) volume of 80% alcohol. Geranium oil: 0.8994,1.4730, -10.980 and soluble in (2.1-8.8) volume of 70% alcohol. French basil oil: 0.9047, 1.4816, -12.7Ioandsolublein(1.4- 3.8) volume of75% alcohol. Corinader oil: 0.8826, 1.4722, + 11.89° and soluble in (2.2-3.1) volume of 70% alcohol. Spearmint oil: 0.9283,1.4817, -31.69° and soluble in (1.6-2.6) volume of 70% alcohol. peppermint oil: 0.9108,1.4650, -19.43° and soluble in (3.1-4.1) volume of 70% alcohol. Neroli bigarade oil: 0.8922, 1.4682, +9.86 and soluble in (0.9- 4.6) volume of 80% alcohol. ----------------- 84 2- The chemical properties (acid number, ester number, ester number after acetylation and free alcohols %) of each oil were as follow: Lemongrass oil: 3.84, 20.28 and 214.81. Geranium oil: 4.4, 51.41, 212.35 and 51.24% as geraniol. French basil oil: 4.76, 7.79, 129.63 and 36.86% as linalool, Corinader oil: 9.72, 18.14, 125.4 and 46.97% as linalool. Spearmint oil: 0.82, 33.32 and 121.12. peppermint oil: 0.64, 19.15, 156.87 and 42.76% as menthol. Neroli bigarade oil: 2.75, 136.24, 164.38 and 27.9% linalool. 3- The chemical composition of the essential oils were determined by gas liquid chromatography and the main components of these oils were citra] 33.750/0(lemongrass), citronellol 13.98%, geraniol 25.99% (geranium), linalooI29.53%, 44.28% (french basil, coriander), carvone 30.76% (spearmint), menthol 31.07% (peppermint) and linaly acetate 29.07%, linalool 15.42% (neroli bigarade). 4- The essential oil and their main components were tested for antimicrobial activity by using filter paper disc diffusion method and the results were as follow: a) All tested essentials had antibacterial activity against growth of Gram-negative and positive bacteria. Lemongrass oil had the highest effect while coriander, and neroli bigarade oils had the lowest one. The Gram-positive bacteria were 85 more sensitive twords the tested essential oil than Gramnegati ve ones. b) All tested essential oils had antifungal activity against growth of fungi and yeasts under study. Lemongrass oils had the highest effect while peppermint oil had the lowest one. The tested yeasts were more sensitiv towards the essential oils under study than that of fungi. c) The main components of the essential oil under study had different effects against growth of Gram-negative and positive bacteria with an exception in case of linalyl acetate which had no effect on growth of E. coli. Geraniol, citronellol and citral had a high effect while linalool, carvone, menthol and linalyl acetate had a mild effect on growth of tested bacteria. Gram-positive bacteria were more sensitive towards the essential oils than that of Gramnegative ones. d) The main components of the tested essential oils had different effects against growth of fungi and yeasts under study with an exception in case oflinalool which had no effect against growth of A. niger. Citral, geraniol and citronellol had a high effect against growth of fungi and yeasts while, linalool, carvone, menthol and linalyl acetate had lower effect against growth of the tested fungi and yeasts. Yeasts were found to be more sensitive towards the main component if compared with fungi. |