ANTIOXIDANT ACTIVITIES OF ESSENTIAL OILS 397 of variance (ANOVA). Differences were considered signifi cant at p 0.05. Data were cal- culated by employing the statistical software SPSS (version 13.0, SPSS Inc., Chicago, IL). RESULTS AND DISCUSSION ANALYSIS OF CHEMICAL COMPOSITION BY GC-MS The name, scientifi c name, department, origin, extraction method, and extraction part for the twenty-fi ve essential oils studied herein are listed in Table I. GC-MS was used to analyze the chemical components of the essential oils cinnamon bark extra, ajowan, and oregano. The GC-MS data revealed the presence of fi ve chemical components, which are Table I Essential Information for the Twenty-Five Essential Oils Studied No. Name Scientifi c name Department Origin Extraction method Extraction part 1 Ajowan Trachyspermum ammi Apiaceae India Distillation Seed 2 Anis extra Pimpinella anisum Apiaceae Turkey Distillation Whole plant 3 Bay laurel Laurus nobilis Lauraceae Turkey Distillation Leaf 4 Benzoin Styrax benzoin Styracaceae Indonesia Solvent extraction Resin 5 Cinnamon bark extra Cinnamomum verum Lauraceae Sri Lanka Distillation Bark 6 Fir Abies sibirica Pinacea Siberia Distillation Conifer 7 Frankincense Boswellia carterii Burseraceae India Distillation Resin 8 Galbanum Ferula galbanifl ua Apiaceae Iran Distillation Resin 9 Ginger Zingiber offi cinalis Zingiberaceae Vietnam Distillation Root 10 Grapefruit extra Citrus paradisi Rutaceae Israel Cold compression Pericarp 11 Ho-oil Cinnamomum camphora Lauraceae China Distillation Leaf 12 Jasmine (arab.) Jaminum sambac Floral-scented oils India Solvent extraction Flower 13 Lavender Kashmir Lavendula angustifolia Lamiaceae India Distillation Whole plant 14 Lemongrass extra Cymbopogon fl exuosus Poaceae Nepal Distillation Leaf 15 Lemonmint Mentha citrata Lamiaceae India Distillation Whole plant 16 Litsea Litsea cubeba Lauraceae China/Vietnam Distillation Fruit 17 Nutmeg Myristica fragrans Myristicaceae Indonesia Distillation Fruit 18 Oregano Origanum vulgare Lamiaceae Turkey Distillation Whole plant 19 Palmarosa Cymbopogon martini Poaceae Nepal Distillation Whole plant 20 Patchouli Pogostemon cablin Lamiaceae Indonesia Distillation Whole plant 21 Pepper extra Piper nigrum Piperaceae Madagascar Distillation Fruit 22 Peppermint Mentha piperita Lamiaceae India Distillation Whole plant 23 Sandalwood Santalum album Santalaceae India Distillation Wood 24 Spikenard Nardostachys jatamansi Valerianaceae Nepal Distillation Root 25 Wintergreen Gaultheria fragrantissima Ericaceae Nepal Distillation Leaf

JOURNAL OF COSMETIC SCIENCE 398 summarized in Table II and account for 98.96% of total cinnamon bark extra essential oil. The major component (90.61%) was found to be trans-cinnamaldehyde (Table II), while the four other components were eugenol (2.58%), p-cymene (2.28%) β-caryophyllene (2.10%), and linalool (1.39%), respectively. There are two major chemical components, carvacrol (61.20%) and p-cymene (37.44%) in the essential oil ajowan (representing 98.64% of the oil). The essential oil oregano contains four major chemical components, namely thymol (77.09%), p-cymene (10.01%), linalool (9.59%), and carvacrol (2.06%), which represent 98.75% of the oil. In order to study the antioxidant activities of these major chemical components, these essential oils were purchased in their pure form. DPPH FREE-RADICAL SCAVENGING ACTIVITY The DPPH free-radical scavenging activity data of the twenty-fi ve essential oils are listed in Table III. At a concentration of 1 mg ml−1, the cinnamon bark extra essential oil showed 93.75 ± 0.01% DFRS. This DFRS activity was followed by the essential oils benzoin (90.64 ± 0.01%), nutmeg (86.88 ± 0.01%), spikenard (72.40 ± 0.01%), ajowan (70.30 ± 0.01%) and oregano (59.20 ± 0.01), respectively. The remaining essential oils had apparent DFRS values below 50%. The EC50 value of cinnamon bark extra was 64.31 μg ml−1 (Figure 1), followed by benzoin (292.46 μg ml−1), nutmeg (481.26 μg ml−1), spikenard (540.86 μg ml−1), and ajowan (629.67 μg ml−1). Compared to the positive control BHT, cinnamon bark extra essential oil showed the best DFRS (Figure 2). The EC50 values of the essential oils Cleistocalyx operculatus (12), Artemisia scoparia (13), Satureja cuneifolia (27), and Thymus caramanicus (28) are 807 μg ml−1, 66 μg ml−1, 65 μg ml−1, and 263 μg ml−1, respectively. Therefore, the DFRS of cinnamon bark extra (Cin- namomum verum) is better than that of Cleistocalyx operculatus and Thymus caramanicus and similar to that of Artemisia scoparia and Satureja cuneifolia. Table II Composition of the Essential Oils from Cinnamon Bark Extra, Ajowan, and Oregano Peak area % a Rt Compoundb M. f.c Cinnamon bark extra Ajowan Oregano 10.32 p-Cymene C10H14 2.28 37.44 10.01 12.53 Linalool C10H18O 1.39 9.59 19.96 trans-Cinnamaldehyde C9H8O 90.61 20.92 Carvacrol C10H14O 61.20 2.06 21.29 Thymol C10H14O 77.09 23.35 Eugenol C10H12O2 2.58 25.45 β-Caryophyllene C15H24 2.10 Unknown 1.04 1.36 1.25 a Rt: Retention time (min). b The components were identifi ed by their mass spectra and retention indices (Rls) and by the Wiley and NIST mass spectral databases and previously published Rls. c M. f.: Molecular formula.