Antioxidant Activities of Essential Oil Mixtures toward Skin Lipid Squalene Oxidized by UV Irradiation

Abstract

Antioxidant activities of essential oil mixtures—thyme or clove leaf with cinnamon leaf, rose, or parsley seed—toward skin lipid, squalene oxidized by UV irradiation were investigated using the malonaldehyde/gas chromatography assay. At all concentrations (50, 100, or 500 μg/mL) tested, thyme oil mixed with 500 μg/mL clove oil showed over 90% inhibitory effect against malonaldehyde formation. The order of potency of all oils mixed together at 500 μg/mL was thyme/clove leaf (93%) > clove leaf/parsley seed = clove leaf /rose (87%) > thyme/parsley seed (83%) > clove leaf/cinnamon leaf (77%) > thyme/parsley seed (71%) > thyme/cinnamon leaf (7%). In comparison, the inhibitory activities of 500 μg/mL of BHT or α-tocopheroltoward malonaldehyde formation were 85% and 76%, respectively. Pro-oxidant effects were observed for some mixtures of thyme with cinnamon leaf or rose oils. The potent antioxidant effects resulting from a mixture of thyme and clove leaf oils may be due to the presence of thymol and eugenol.

Keywords :

• Antioxidants
• Essential oil
• Oxidation
• Skin lipid
• Squalene
• UV irradiation