ANTIOXIDANT ACTIVITIES OF ESSENTIAL OILS 399 At a concentration of 1 mg ml−1, the essential oil cinnamon bark extra and three of its main components (trans-cinnamaldehyde, eugenol, and p-cymene) were analyzed for their DFRS activity. In Figure 3, it is clear that the DFRS increases is in the following order: eugenol cinnamon bark extra essential oil trans-cinnamaldehyde p-cymene. Eugenol was the major chemical component attributed to the high DFRS value for the cinnamon bark extra essential oil. The other major components, trans-cinnamaldehyde and p-cymene, yielded DFRS values of 6.01% and 4.55%, respectively. TOTAL PHENOLIC CONTENT (TPC) The TPC of the twenty-fi ve essential oils studied herein were expressed as equivalents of gallic acid (GAE 10 mg−1). The results are shown in Table III, and the essential oils were Table III DFRS, TPC, TEAC, and FTC Assays of the Twenty-Five Essential Oils No. Name DPPH free- radical scavenging activity (%)* Total phenolic content (μg of GAE 10 mg−1)* TEAC (μM of trolox mg−1) Inhibition of linoleic acid peroxidation (%)* 1 Ajowan 70.30 ± 0.01 1845.20 ± 0.04 4374.72 ± 0.01 25.26 ± 0.03 2 Anis extra 4.24 ± 0.01 15.51 ± 0.02 206.83 ± 0.02 — 3 Bay laurel 40.89 ± 0.01 28.23 ± 0.02 204.49 ± 0.01 4.89 ± 0.04 4 Benzoin 90.64 ± 0.01 90.53 ± 0.10 508.89 ± 0.01 18.59 ± 0.03 5 Cinnamon bark extra 93.75 ± 0.01 544.35 ± 0.01 1190.23 ± 0.01 10.46 ± 0.05 6 Fir — 6.39 ± 0.02 88.58 ± 0.01 — 7 Frankincense 1.26 ± 0.01 10.01 ± 0.04 44.09 ± 0.01 — 8 Galbanum — 9.56 ± 0.02 48.78 ± 0.01 — 9 Ginger 4.26 ± 0.01 16.72 ± 0.03 115.51 ± 0.01 — 10 Grapefruit extra — 6.86 ± 0.03 79.22 ± 0.01 — 11 Ho-oil — 4.59 ± 0.01 82.73 ± 0.01 — 12 Jasmine (arab.) 31.93 ± 0.01 47.75 ± 0.04 278.25 ± 0.04 13.70 ± 0.03 13 Lavender Kashmir — 8.03 ± 0.04 121.36 ± 0.01 — 14 Lemongrass extra 16.90 ± 0.01 21.22 ± 0.03 99.12 ± 0.01 — 15 Lemonmint — 8.58 ± 0.01 95.61 ± 0.01 — 16 Litea 3.69 ± 0.01 9.21 ± 0.02 89.75 ± 0.01 — 17 Nutmeg 86.88 ± 0.01 85.24 ± 0.04 363.71 ± 0.01 5.81 ± 0.05 18 Oregano 59.20 ± 0.01 1665.36 ± 0.04 4023.49 ± 0.01 29.17 ± 0.02 19 Palmarosa 5.13 ± 0.01 7.31 ± 0.02 97.95 ± 0.01 — 20 Patchouli 1.39 ± 0.01 22.16 ± 0.01 46.44 ± 0.01 — 21 Pepper extra 6.18 ± 0.01 10.84 ± 0.02 17.17 ± 0.01 — 22 Peppermint 1.79 ± 0.01 13.92 ± 0.01 176.39 ± 0.01 — 23 Sandalwood 1.91 ± 0.01 13.86 ± 0.04 89.75 ± 0.01 — 24 Spikenard 72.40 ± 0.01 58.44 ± 0.08 253.66 ± 0.01 — 25 Wintegreen 4.66 ± 0.01 7.01 ± 0.01 3847.87 ± 0.01 — Values are mean ± S.D. (n = 3). The concentrations of each essential oil for DFRS, TPC, TEAC, and FTC assay were 1 mg ml−1, 10 mg ml−1, 1 mg ml−1, and 1 mg ml−1, respectively. * Antioxidant activity has not been observed.

JOURNAL OF COSMETIC SCIENCE 400 found to have various phenolic levels, which ranged from 4.59 to 1845.20 μg of GAE 10 mg−1. For each 10 milligrams of essential oil, ajowan had the highest TPC (1845.20 ± 0.04 g of GAE), followed by oregano (1665.36 ± 0.04 μg of GAE) and cinnamon bark extra (544.35 ± 0.01 μg of GAE). The lowest TPC values were given by the essential oils, ho-oil (4.59 ± 0.01 μg of GAE) followed by fi r (6.39 ± 0.02 μg of GAE). The TPC of the essential oils Psammogeton canescens (14), Pistacia lentiscus, Myrtus communis extract (15), and Satureja cuneifolia (27) are 340, 4830, 3070, and 1855 μg of GAE, re- spectively. Therefore, the TPC of the essential oil ajowan (Trachyspermum ammi) is better than that of Psammogeton canescens, similar to that of Satureja cuneifolia, but lower than that of Pistacia lentisus or Myrtus communis extract. TROLOX EQUIVALENT ANTIOXIDANT CAPACITY (TEAC) ASSAY The TEAC assay was used to analyze the concentration of the twenty-fi ve essential oils relative to that of a standard sample of trolox (25-800 μM), and the results are shown in Table III. At a concentration of 1 mg ml−1, ajowan was the best essential oil (4374.72 ± 0.01 μM of trolox mg−1) based on the TEAC assay results. The TEAC assay results for Figure 1. DPPH free-radical scavenging activity in different concentrations for cinnamon bark extra essential oil. Figure 2. Concentration-dependent effect of DPPH free-radical scavenging activity of cinnamon bark extra essential oil and BHT.