In vitro antioxidant activity of a number of plant essential oils and phytoconstituents

The antioxidant capacity of the synthetic antioxidants BHA, BHT, pyrogallol and alpha-tocopherol, the essential oils from black pepper, clove, geranium, melissa, nutmeg, oregano and thyme and 33 phytoconstituents were assessed in vitro, using an antioxidant assay. All the compounds demonstrated antioxidant capacity superior to the water soluble alpha-tocopherol analogue Trolox with the exception of the essential oil melissa and the phytoconstituents aromadendrene, myrcene and nerol. Clove, oregano and thyme were exceptionally potent in this assay, comparable with the activities of both BHA and pyrogallol. Eugenol, carvacrol, and thymol similarly demonstrated an equivalent degree of activity. These phytoconstituents are the major components present in clove, oregano and thyme essential oils, respectively.