Free Radical Scavenging Activities of Four Thymus Species


Bahman Nickavar, Mohammad Reza Rezakhani and Faraz Mojab


Traditional & Complementary Medicine Exhibition 2007 (TCME 2007), Putra World Trade Centre (PWTC), Kuala Lumpur, Malaysia




Free radical, Thymus, antioxidant


Recently there has been an increase of interest in free radicals in biological systems and their roles as causative agents in a variety of chronic disorders. Accordingly, attention is being focus on the protective biochemical functions of naturally occurring antioxidants in the cells of the organisms containing them and it has also been recognized that naturally occurring substances in higher plants have antioxidant activity. The genus Thymus is one of the worthwhile members of Labiatae family. Thymus species are commonly used as herbal tea, flavoring agents (condiment and spice) and medicinal plants. Infusion and decoction of aerial parts of Thymus species are used as tonic, carminative, digestive, antispasmodic, anti inflammatory, antitussive, expectorant and for the treatment of colds in traditional Iranian medicine. This study was designed to examine the in-vitro free radical scavenging (FRS) activities of the ethanol extracts obtained from aerial parts of four Thymus species(T. daenensis,T. kotschyanus,T. pubescens,T. vulgaris) using the stable DPPH and ABTS radicals. The in-vitro FRS activities were spectrophotometrically evaluated by quantitative DPPH and ABTS assays. The positive control used was rutin. The FRS activity of each extract was expressed as an IC50 value and calculated from Log concentration–response curve. The results were statistically compared by one-way ANOVA to see the significance. All examined extracts have FRS activities in both methods. In DPPH system, the most active plant wasT. pubescenswith an IC50 value of 32.49 μg/ml (IC50 = 29.91 – 35.30 μg/ml). On the other hand,T. pubescensexerted greater FRS activity than those of other species in ABTS system with an IC50 value of 165.5 μg/ml (IC50 = 154.7 - 177.2 μg/ml). The results indicate that the extract ofT. pubescenshas a very potent FRS activity compared withT. vulgaris(common thyme) extract. The results of this study indicate that some Thymus species, especiallyT. pubescensecan serve as natural source to develop the free radical scavengers and might prevent radicals attack in biological and food systems.