Antioxidant/lipoxygenase inhibitory activities and chemical compositions of selected essential oils.
Twenty-five essential oils were tested for antioxidant activities using a conjugated diene assay, the aldehyde/carboxylic acid assay, the DPPH free radical scavenging assay, and the malonaldehyde/gas chromatography (MA/GC) assay. They were also tested for lipoxygenase inhibitory activities using the lipoxygenase inhibitor-screening assay. Thyme oil exhibited the greatest antioxidant effect in all assays (80-100%) except in the DPPH assay (60%). Clove leaf oil showed activities comparable to those of thyme oil (53-100%). Cinnamon leaf oil showed strong activities in the aldehyde/carboxylic acid assay (100%) and DPPH assay (84%), but only moderate activities in the conjugated diene assay (24%) and MA/GC assay (48%). Basil oil exhibited a strong effect in the DPPH assay (86%) and moderate activities in the MA/GC assay (35%). Bergamot oil exhibited 100% antioxidant activity in the aldehyde/carboxylic acid assay. Eucalyptus and chamomile oils showed appreciable activities only in the conjugated diene assay. Bitter orange oil exhibited moderate antioxidant activity (53%) only in the MA/GC assay. Aloe vera oil exhibited the greatest lipoxygenase inhibitory activity (96%), followed by thyme oil (86%) and bergamot oil (85%) at a concentration of 0.5 microg/mL. Chamomile oil showed slight lipoxygenase inhibitory activity at 0.5 microg/mL but strong lipoxygenase inducing activity at 5 microg/mL (-123%). Thyme and clove leaf oils contained high levels of thymol (23%) and eugenol (77%), respectively, as a principal of the antioxidant activity. The results obtained in the present study suggest that some essential oils possess strong medicinal activities, which can be utilized for treatment of certain diseases.
Wei
Alfreda
A
Department of Environmental Toxicology, University of California, Davis, California 95616, USA.
Shibamoto
Takayuki
T
D000975:Antioxidants / Q000032:analysis*; D016859:Lipoxygenase Inhibitors / Q000032:analysis*; D009822:Oils, Volatile / Q000032:analysis*; D010938:Plant Oils / Q000032:analysis*; D010944:Plants / Q000737:chemistry*
D000975:Antioxidants; D016859:Lipoxygenase Inhibitors; D009822:Oils, Volatile; D010938:Plant Oils