The in vitro antimicrobial and antioxidant activities of the essential oils and methanol extracts of endemic Thymus spathulifolius Atalay Sokmen a, * , Medine Gulluce b,c , H. Askin Akpulat a , Dimitra Daferera d , Bektas Tepe a , Moschos Polissiou d ,M€ unevver Sokmen e , Fikrettin Sahin f,c a Department of Biology, Faculty of Science and Literature, Cumhuriyet University, 58140 Sivas, Turkey b Department of Biology, Faculty of Art and Science, Atat€ urk University, 25240 Erzurum, Turkey c Atat€ urk University, Biotechnology Application and Research Center, 25240 Erzurum, Turkey d Laboratory of General Chemistry, Agricultural University of Athens, Iera Odos 75, Athens 11855, Greece e Department of Chemistry, Faculty of Science and Literature, Cumhuriyet University, 58140 Sivas, Turkey f Department of Plant Protection, Faculty of Agriculture, Atat€ urk University, 25240 Erzurum, Turkey Received 8 June 2003; received in revised form 15 October 2003; accepted 16 October 2003 Abstract The present study was conducted to evaluate the in vitro antimicrobial and antioxidant properties of essential oil and methanol extracts from a unique and endemic plant, Thymus spathulifolius (Hausskn. and Velen.). The antimicrobial test results showed that the essential oil of T. spathulifolius strongly inhibited the growth of test microorganisms studied, except for 4 fungi species while polar and non-polar subfractions of the methanol extract had moderate antibacterial, but not antifungal and anticandidal activity. The antioxidative potential of the samples was evaluated using two separate methods, inhibition of free radical 2,2-diphenyl-1- picrylhydrazyl (DPPH) and b-carotene–linoleic acid systems. The polar subfraction of the methanol extract was able to reduce the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an IC 50 of16.15±0.5 lg/ml, which was lower than that of synthetic antioxidant,BHT,(19.8±0.5 lg/ml). Inhibition values of linoleic acid oxidation were calculated as 92% and 89% for the oil and the polar subfraction, respectively. Gallic acid equivalent total phenolic constituent of the polar subfraction was 141.00±0.90 lg/mg (14.1%, w/w). The chemical composition of a hydrodistilled essential oil of T. spathulifolius was analyzed by a GC and GC/MS system.Atotalof28constituentsrepresenting99.2%oftheoilwereidentified;thymol(36.5%),carvacrol(29.8%), p-cymene (10.0%) and c-terpinene (6.3%) were the main components comprising 82.6% of the oil. Results presented here may suggest that the essential oil and extracts of T. spathulifolius possess antimicrobial and antioxidant properties, and therefore, they can be used as a natural preservative ingredient in food and/or pharmaceutical industry. Ó 2003 Elsevier Ltd. All rights reserved. Keywords: Thymus spathulifolius; Antimicrobial activity; Antioxidant activity 1. Introduction Synthetic antioxidants such as butylated hydroxy- anisole (BHA) and butylated hydroxytoluene (BHT) are widely used as potential inhibitors of lipid peroxidation and thereby stabilizing fat-containing food-stuffs. However, due to their unstable and highly volatile nat- ure, they have frequently brought some questions about their safety and efficiency ever since their first intro- duction to the food industry (Dapkevicius, Venskutonis, Van Beek, & Linssen, 1998). Also, increasingly adverse drug reactions to the synthetic antibiotics and the increasing resistance of some pathogens to synthetic antibiotics, has been another argument against the use of these chemicals as therapeutics (Agnihotri & Vaidya, 1996; Friedman, Henika, & Mandrell, 2002). Commercial antimicrobial drugs/chemicals used haphazardlyinthetreatmentofmanyinfectiousdiseases has inevitably led multiple drug/chemical resistance in both human and plant pathogenic microorgan- isms (Davis, 1994; Loper et al., 1991; Service, 1995). Besides, food-borne diseases are still a major problem in the World, even in well-developed countries (Mead et al., 1999). A variety of microorganisms also lead food spoilage that is encountered as one of the most * Corresponding author. Tel.: +90-346-219-1010x2907; fax: +90- 346-219-1186. E-mail address: asokmen@cumhuriyet.edu.tr (A. Sokmen). 0956-7135/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodcont.2003.10.005 Food Control 15 (2004) 627–634 www.elsevier.com/locate/foodcont