Life Science Journal 2013;10(4) http://www.lifesciencesite.com 2401 Extraction Methods Effects on Composition and Toxicity of Eucalyptus Essential Oil Mohammad Ebrahim Farashiani 1,2 , Rita Muhammad Awang 1 Fatemeh Sefidkon 2 , Dzolkhifli Omar 1 , Mohammad Hassan Assareh 3 and Mawardi Rahmani 4 , 1. Department of Plant Protection, Universiti Putra Malaysia, 43400, UPM Serdang, Selangor, Malaysia. rita@agri.upm.edu.my , EbrahimFarashiani@yahoo.com 2. Department of Plant Medicine, Research Institute of Forests & Rangelands, (RIFR), Tehran, Iran 3. Department of Biotechnology, Research Institute of Forests & Rangelands, (RIFR), Tehran, Iran 4. Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400, UPM Serdang, Selangor, Malaysia Abstract: The current investigation was designed to determine the influence of three extraction methods on the composition and insecticidal activity of essential oils extracted from Eucalyptus globulus and E. camaldulensis. The evaluated extraction methods were steam-distillation, steam water-distillation and hydro-distillation. Fumigant toxicity of the extracted essential oils was evaluated against Sitophilus oryzae. The GC and GC–MS methods were used for analyzing the oil chemical composition. Both E. globulus and E. camaldulensis showed significant differences in oil yield (w/w, based on dry weight) with direct steam distillation resulting in low oil yields (0.8%; 0.35%) compared to water distillation (2.35%; 2.22%) and water + steam distillation (2.03%; 1. 53%). We identified nineteen compounds in the essential oils of these species. 1, 8-Cineol (27.67-82%), α-Pinene (4.67-8.13%) and Limonene (2.49-10.53%) were the major components of the oils and the highest amount of 1, 8-Cineol (82%) was obtained with water distillation, while steam-distillation resulted in the lowest amount of Cineol (27%). The results of the toxicity study of the essential oils demonstrated that the highest toxicity (LC 50 = 24.89 µL/L air) was observed against S. oryzae populations treated with oils extracted by water distillation. In conclusion, the extraction of Eucalyptus essential oils by hydro-distillation had some priorities over the oil extractions by the other methods because hydro-distillation extracted oil had the highest fumigant activity, high and fast-oil yields as well as high percentage composition of 1,8-Cineol. [Farashiani ME, Muhammad Awang R, Sefidkon F, Omar D, Assareh MH, Rahmani M. Extraction Methods Effects on Composition and Toxicity of Eucalyptus Essential Oil. Life Sci J 2013;10(4):2401-2405]. (ISSN:1097- 8135). http://www.lifesciencesite.com . 321 Keywords: Eucalyptus Essential oil; extraction methods; 1, 8-Cineol, fumigant toxicity, Sitophilus oryzae 1. Introduction Eucalypt trees are evergreen and they belong to Eucalyptus genus, Myrtaceae family. Eucalyptus genus is native to Australia and there are more than 700 Eucalyptus species (Brooker and Kleinig, 2006). Eucalyptus trees are fast growing and they are planted in a wide range of climate for timber, pulp and wood- fuel crop. They are also planted for their essential oils (Brooker and Kleinig, 2006). Most of the Eucalyptus trees (about 500 species of them) produce some types of essential oils. Based on the use of Eucalyptus essential oils, they are grouped into three types namely industrial, medicinal and perfumery (Boland et al., 1991). In the European Pharmacopeia, the Eucalyptus oil with more than 70% 1, 8-cineole has been used as medicinal products (Brooker and Kleinig, 2006; FAO, 1995). The essential oils of Eucalyptus are also important as they have insecticidal properties and have been used as natural pesticides (Haouel et al., 2010; Lee et al., 2004; Lee et al., 2000; Papachristos and Stamopoulos, 2004). There are some factors that may influence the quality and quantity as well as the insecticidal properties of Eucalyptus essential oils and the method of oil distillation is probably one of the important factors. Water and steam-distillation, hydro- distillation (water-distillation) and steam-distillation are three main methods for extracting Eucalyptus essential oils (Boland et al., 1991; Handa et al., 2008). There is a considerable body of published studies describing the role of different distillation methods on the quantity, chemical composition and substance of essential oils in plants. For example Kiran et al. (2005) demonstrated that the amount of the rose- scented geranium essential oil (0.16–0.22%) obtained by hydro-distillation methods was more than steam- distillation extracted oil (0.06–0.18%) or oil extracted by water-steam distillation method (0.09–0.12%). Also, the used extraction method had significant influences on the oil component percentage (Kiran et al., 2005). The influence of extraction methods and stages of plant maturation on Thymus kotschyanus essential oil composition and content have also been reported. The most essential oil was extracted by