Table III MIC and MBC Concentration Values of EOs (v/v %)on Standard Strains Causing Acne Bacteria Activity Or La Le Sa Ci Te Eu Lau S epidermidis ATCC 12228 MIC MBC 0.03125 0.03125 1.00 2.00 16.00 32.00 32.00 32.00 0.25 0.50 0.50 1.00 4.00 8.00 – C acnes ATCC 6919 MIC MBC 0.0625 0.0625 16.00 32.00 – 16.00 16.00 2.00 4.00 1.00 2.00 32.00 64.00 4.00 4.00 Or: oregano La: lavender Le: lemon Sa: sandalwood Ci: cinnamon Te: tea tree Eu: eucalyptus Lau: laurel. 22 JOURNAL OF COSMETIC SCIENCE

23 CHARACTERIZATION AND ACTIVITY OF ESSENTIAL OILS effect the combination of tea tree/sandalwood (FICI: 1.03) and lemon/eucalyptus (FICI: 1.00) exhibited an additive effect, and lemon/lavender (FICI: 2.00) showed no interactive effect against S epidermidis. The binary combination of lemon/sandalwood showed no interactive effect with FICI values of 1.95 and 2.13 against either bacterium (48). In this study, different interactions in the dual combination of EOs were observed. ANTIOXIDANT ACTIVITY OF ESSENTIAL OILS Free radical scavenging activity. The antioxidant amount of each EO was calculated by the IC 50 (effective concentration) value and is displayed in Table VI. The C verum EO showed the greatest (IC 50 :35.08 µg/ml) antioxidant activity. It is likely due to the high antioxidant capacity of eugenol (49). Our results were similar to previous studies with IC 50 values: 62.01 mg/ml (Origanum vulgare) (50) 57 µg/ml (28) and 2.23 mg GAE/l (51) (E globulus) 48.35 µg/ml (M alternifolia) (52) 31.30 µg/ml (L angustifolia) (30) and 35.35 µg/ml (C limon) (53). On the other hand, some studies have reported different IC 50 values. For O vulgare 23.96 and 0.332 (mg/ml) (37,38) for E globulus 10 (mg/ml) (33) for M alternifolia 12.5 (µg/ml) (28) for L angustifolia 2.51 (v/v) (31) for C limon 15.056 (µg/ml) (27) for C verum 13.3, 0.03, and 111.5 (µg/ml) (54–56) and for S album 0.87 (µg/ml) and 74.85 (mg/ml) (57,58). Several biochemical mechanisms and various factors like plant maturity, plant species, and organs (leaf, stem, e.g.), geographical origin, extraction method, and harvest season may affect the antioxidant properties of EOs (59). Table IV FIC and FICI Values in Dual Combination of EOs Against S epidermidis EOs in combination (EO1/EO2) S epidermidis ATCC 12228 FIC1/FIC2 FICI Remarks Or/Ci 1.00/0.13 1.13 NI Or/La 1.00/0.02 1.02 NI Or/Te 1.00/1.00 2.00 NI Or/Sa 1.00/0.00 1.00 AD Ci/La 0.25/0.13 0.38 S Ci/Te 0.50/0.13 0.63 AD Ci/Sa 0.50/0.00 0.50 S La/Te 1.00/0.06 1.06 NI La/Sa 0.13/1.00 1.13 NI Te/Sa 0.25/1.00 1.25 NI Eu/Le 1.00/0.02 1.02 NI Or/Eu 4.00/0.031 4.03 A Eu/Ci 0.02/0.25 0.27 S Eu/La 0.25/0.25 0.50 S Eu/Te 0.13/0.25 0.38 S Sa/Eu 1.00/1.00 2.00 NI Or/Le 1.00/0.50 1.50 NI Le/Ci 0.00/0.25 0.25 S Le/La 1.00/0.13 1.13 NI Le/Te 0.50/1.00 1.50 NI Sa/Le 0.25/0.5 0.75 AD Or: oregano, La: lavender, Le: lemon, Sa: sandalwood, Ci: cinnamon, Te: tea tree, Eu: eucalyptus FICI ≤ 0.5: synergy (S) 0.5 FICI ≤ 1: additive (AD) 1 FICI ≤ 4: no interactive effect (NI) FICI 4: antagonistic (A).