Essential oils as powerful antioxidants: Misconception or scientific fact?

Abstract

© 2016 American Chemical Society. Many aromatic plants and spices are well-known for their various beneficial effects on human health. Recently, a considerable number of studies are focused on antioxidant activity of essential oils and aromatic plants. Considerable number of articles revealed that volatile compounds and essential oils possess strong radical scavenging capacity and ability to inhibit lipid peroxidation, especially in food and cosmetic products. However, the chemical nature of essential oils and enormous variability of oil composition made comparison of the published results very difficult. The other serious problem in interpretation of the published results is large diversity of analytical methods for determination of antioxidant capacity. These assays differ from each other in terms of reaction mechanisms, oxidant and target/probe species, reaction conditions, and in the form that the results are expressed. A single-substance/single-assay produces relative results whenever a complex mixture is involved. Therefore, a multiple-test and a simultaneous chemical characterization must be taken into account whenever assays of essential oils are performed. Furthermore, volatile compounds in essential oil, beside their protective and antioxidant activity can also act as prooxidant, by affecting the cellular redox status and damage cellular biomolecules, in the first instance proteins and DNA. All these must be taking into account when antioxidant properties of essential oils are considered. However, summing up the large numbers of recent publications, one can conclude that essential oils of plant species like oregano, thyme, sage, lemon balm, basil and some other aromatic plants are of considerable importance as the source of natural antioxidant substances.