University Publications

Introduction: Medicinal plants play a vital role in drug discovery, and there is a worldwide interest in searching for new safe photochemical compound drugs. As the long-term uses of NSAIDs cause adverse side effects and damage human biological system such as liver, gastrointestinal tract etc. Objective: The goals of this research is to analyze the chemical compounds of lemon peel essential oil using GC-MS and to investigate its in-vitro capabilities to inhibit protein denaturation as an anti-inflammatory and its antioxidant properties. Methodology: Essential oil was prepared by using hydrodistillation technique. Ten milliliters of the essential oil of lemon were analyzed using Gas Chromatography-mass spectroscopy (GC/MS) at the Department of Biochemistry, the University of Science and Technology. The anti-inflammatory activity was carried out according to modification of the in-vitro protein denaturation bioassay methods of Jagtap et al (2011) and Shallangwa et al (2013). Ten milliliters of oil were mixed with DMSO and diluted with PBS (0.2M, pH7.4). The test mixtures (5 ml each) made up of 0.2 ml of egg albumin, 2.8 ml of PBS (pH7.4) and 2ml of varying concentrations of the extract. Test solution was incubated at 37oC in Corsair Heating and Catering limited incubator for 15 min. Denaturation was induced at 60oC in water-bath for 10min after cooling the turbidity was measured at 660nm. Diclofenac sodium was used as reference drug. Each experiment was done in triplicate and average was taken. The percentage of inhibition of denaturation was calculated. The antioxidant activity of the oil was assessed against the standard (Ascorbic acid), based on radical scavenging effect of the stable 1, 1-DPPH-free radical activity. The diluted working solutions of the test extracts were prepared in methanol, where oil was prepared in DMSO. A solution of 0.004% of DPPH was prepared in methanol and only 1 ml of it was mixed with 1 ml of sample solution or standard solution. These mixtures were kept in dark for 30 min. The optical density was measured at 517 nm and percentage of inhibition was calculated. Results and discussion: Analysis of the essential oil by GC-MS has shown that lemon essential oil is rich with D-Limonene and Geraniol. Inhibition of protein albumin denaturation by essential oil was increased in a dose-dependent manner at concentration of 400 to 2000µg/ml (123% and 138.5%, respectively). However, essential oil exhibited moderate antioxidant activity; the maximum activity was determined at 1000µg/ml. (60.84+0.25%). IC50 value for essential oil was amounted to 912.74µg. The presence of these bioactive components (Limonene and Geraniol) may be behind the anti-inflammatory and antioxidant activities of lemon essential oil. Conclusion and recommendation: The essential oil of lemon was capable of limiting the process of protein denaturation, and possess antioxidant activity; these activities are related to the major terpenoids and other lemon constituents detected by GC-MS. Therefore, we recommend further investigation for designing potent anti-inflammatory and antioxidant drugs