518 JOURNAL OF COSMETIC SCIENCE Table IV Variation in Content of Essential Oil Components from Clove Bud Peak number Ra I Compound6 Mol. wt.c Mol. f.d Area(%) 27.87 Eugenol 164 C10H12O2 82.32 2 30.62 13-Caryophyllene 204 C15H24 4.75 3 34.62 Eugenol acetate 206 C12H14O3 11.17 * Unknown 1.76 a R,: Retention time (min). 6 The components were identified by their mass spectra and retention indicators (Rls), the Wiley and NIST mass spectral databases, and the previously published Rls. c Mol. wt: molecular weight. d Mol. f.: molecular formula. 100 � 80 71.1 -� 60 ·.c u ca c:: "iii) 40 c:: ca u 20 0 Eugenol 4.18 P-Carophyllene Eugenol acetate Concentration (0. ImwmL) 64.6 Clove bud Figure 5. DPPH radical scavenging activity of three pure chemical components of clove bud compared with its essential oils at a concentration of 0.1 mg/ml. benzoate (32.2%) and benzyl acetate (17.24%). In Figure 6, it is clear that the DPPH free-radical scavenging activity is in the following order: eugenol jasmine absolute essential oil p-cresol J3-farnesene indole jasmone benzyl alcohol benzyl acetate benzyl benzoate J3-linalool. The total contribution (percentage of content multiplied by the DPPH free-radical scavenging activity) of the DPPH free-radical scavenging activity is in the following order: benzyl acetate benzyl benzoate p-cresol eugenol indole J3-farnesene jasmone benzyl alcohol J3-linalool. Benzyl acetate is the major component of the DPPH free-radical scavenging activity in jasmine absolute essential oil. In Table VI, there are eight compounds: cx-pinene, camphene, p-cymene, d-limonene, crithmene, J3-linalool, thymol, and carvacrol in thyme red essential oil, and the two major compounds are thymol (63.65%) and p-cymene (23.8%). In Figure 7, it is clear that the DPPH free-radical scavenging activity is in the following order: thymol thyme red essential oil p-cymene and that thymol is the major component of the DPPH free-radical scavenging activity in thyme red essential oil. From the above description, it is clear that the phenol compound is always effective in the DPPH free-radical scavenging activity. It is conclusive that the phenol compound

DPPH FREE-RADICAL SCAVENGING ABILITY 519 Table V Variation in Content of Essential Oil Components from Jasmine Absolute Peak number Ra I Compound6 Mol. wt.c Mol. f.d Area(%) 12.45 Benzyl alcohol 108 C7H8O 2.47 2 13.87 p-Cresol 108 C7H8O 3.66 3 14.77 J3-Linalool 154 C10H1sO 2.72 4 17.09 Benzyl acetate 150 C9H10O2 17.24 5 21.68 Indal 117 C8H7N 3.44 6 23.61 Eugenol 164 C10H12O2 0.87 7 24.94 Jasmone 164 C11H6O 2.32 8 28.34 Farnesene 204 C15H24 2.52 9 36.38 Benzyl benzoate 212 C14H12O2 32.2 10 44.90 Isophyrol 296 C20H40O 7.38 11 48.83 Phytol 296 C20H40O 16.97 12 58.28 Squalene 410 C30H50 5.29 * Unknown 2.92 a R,: Retention time (min). 6 The components were identified by their mass spectra and retention indicators (Ris), the Wiley and NIST mass spectral databases and the previously published Ris. c Mol. wt: molecular weight d Mol. f.: molecular formula. - 80 � ... :� 6() ... C J ffl 20 Benzylalcohol jKn:sol Linalool Benzylacetate 88.1 36 lndol f.ugenol Jasrronc Faamescoe Benzyl benmale Jasninc absolute Coacenllllioo ( Jmg/a) Figure 6. DPPH radical scavenging activity of nine pure chemical components of jasmine absolute com­ pared with its essential oils at a concentration of 1 mg/ml. shows hydrogen-donating ability and that the resonance structures are stabilized by the benzene ring (Figure 8). Correlation of the phenolic content and the scavenging activity of essential oils is shown in Figure 9. Below 500 mg/g of GAE, it is clear that the total phenolic content and the DPPH free-radical scavenging activity are in direct proportion. CONCLUSION This research reports the DPPH radical scavenging activity and the total phenolic content of forty-five kinds of commonly used essential oils. GC-MS was employed to analyze the main chemical compositions of these essential oils.