DPPH FREE-RADICAL SCAVENGING ABILITY Q N J) I N• 02NhN02 y N02 / HOR Q N J) I NH 02NhN02 y N02 Figure 1. The reaction of DPPH free radical and antioxidant. DETERMINATION OF TOTAL PHENOLIC CONTENT 511 The essential oils were diluted with ethanol to a suitable concentration for analysis. The total phenolic content of essential oils was assessed approximately by using the Folin­ Ciocalteau phenol reagent method (22). To 500 µl of the essential oil were added 1.0 ml of Folin-Ciocalteau reagent and 1 ml of sodium carbonate (7.5% w/v), and the contents were mixed and allowed to stand for 30 min. Absorption at 765 nm was measured in a UV-vis spectrophotometer. The total phenolic amounts were expressed as gallic acid equivalents (GAE) in milligrams per gram of sample, using a standard curve generated with gallic acid. GAS CHROMATOGRAPHY-MASS SPECTROMETRY The analyses of the volatile compounds were run on a Thermo GC-MS system (GC-MS Trace DSQ-Mass Spectrometer, MSD 201351, Thermo, USA). A TR-5MS column was used (5% phenyl polysilphenylene-siloxane, Thermo 30 m·0.25 mm ID., film thickness 0.25 um). The oven temperature was programmed as follows: isothermally at 40°C for 1 min then increased to 250°C, at a rate of 10°C/min and subsequently held isother­ mally for 40 min then increased to 300°C, at a rate of 4 ° C/min. The carrier gas was helium (1 ml/min). The injection port temperature was 220°C and the detector tem­ perature was 280°C. Ionization of the sample components was performed in the EI mode (70 eV). The injected volume was 1 µl. The linear retention indices for all the com­ pounds were determined by co-injection of the samples with a solution containing a homologous series of C8-C22 n-alkanes (23 ). The individual constituents were identified by their identical retention indices referring to the compounds known from the litera­ ture data (24), and also by comparing their mass spectra with spectra of either the known compounds or those stored in the Trace DSQ-MASS spectral database (Thermo, USA). RESULTS AND DISCUSSION DPPH RADICAL SCAVENGING ACTIVITY Information on the forty-five essential oils is listed in Table I. Cinnamon leaf, clove bud, jasmine absolute, and thyme red essential oils have apparently shown DPPH radical scavenging activity in the forty-five kinds of commonly used essential oils. In 10 mg/ml

Table I Information on Forty-Five Essential Oils No. Name Scientific name Department Basil Ocimum basilicum Lamiaceae 2 Bergamot Cutrus aurantium var. Rutaceae bergamia 3 Cajeput ambon Melaleuca cajeputi Myrtaceae 4 Camphor Cinnamomum camphora Lauraceae 5 Cardamom Elettaia cardamomum Zingiberaceae 6 Cedarwood atlas Cedrus atlantica Pinaceae 7 Cinnamon leaf Cinnamomum zeylanicum Lauraceae 8 Clary sage Salvia sclarea Lamiaceae 9 Clove bud Eugenia caryophyllata Myrtaceae 10 Coriander C oriandrum sativum Apiaceae 11 Cypress Cupressus sempervirens Cupressaceae 12 Everlasting Helichrysum italicum Asteraceae 13 Fennel Foeniculum vulgare Apiaceae 14 Frankincense Boswellia carterii Burseraceae 15 Geranium Pelargonium graveolen Geraniaceae 16 Ginger Zingiber officinale Zingiberaceae 17 Grapefruit Citrus X paradisi Rutaceae 18 Jasmine absolute Jasminum grandiflorum Oleaceae 19 Juniperberry J uniperus communis Cupressaceae 20 Lemon Citrus limon Rutaceae 21 Lemon eucalyptus Eucalyptus citriodors Myrtaceae 22 Mandarin Citrus reticulats Rutaceae Extraction Origin method Madagascar Distillation Italy Expression Vietnam Distillation China Distillation Guatemala Distillation Morocco Distillation Madagascar Distillation France Distillation Madagascar Distillation Australia Distillation France Distillation France Distillation France Distillation India Distillation Morocco Distillation Cochin Distillation Australia Distillation India Distillation France Distillation Sicily Expression Sicily Distillation Italy Expression Extraction part Flower, leaf Pericarp Leaf, shoot Leaf Seed Wood Leaf, bark Flower bud, bud Bract Seed Leaf, strobile Flower Seed Resin Flower, leaf Root Pericarp Petal Fruit Pericarp Leaf, withe Pericarp Vl ....... N 0 z r 0 1-rj n 0 V'J tTJ 1--f n V'J n tTJ z n tTJ