Antioxidant and Anti-Inflammatory Activities of Essential Oils: A Short Review

Miguel, Maria Graça

Among the oxygen radicals, hydroxyl is the most reactive one, inducing severe damage to the adjunct biomolecules. There are several ways to ascertain the ability to form hydroxyl radicals. One of them is the deoxyribose test. This method includes a mixture of ferric chloride (FeCl 3 ) and ethylenediamine tetraacetic acid (EDTA), which in the presence of ascorbic acid forms Fe 2+ -EDTA, and oxidized form of ascorbic acid. After addition of hydrogen peroxide (H 2 O 2 ), Fe 3+ -EDTA and HO • are formed. This is the so-called Fenton reaction, which generates the highly reactive hydroxyl radical (Fe 2+ + H 2 O 2 → Fe 3+ + HO− + HO • ). Hydroxyl radicals that are not scavenged by any component of the mixture attack the deoxyribose and degrade it into several fragments. Some of these fragments are capable of reacting with thiobarbituric acid after heating and in an acidic pH, originating a pink pigment that can be quantified by spectrophotometry [5] . There are other methods that did not use deoxyribose but other components such as benzoic acid or safranine. Using these methods several authors have evaluated the hydroxyl radical scavenging ability of essential oils [51, 53, 54, 57, 83, 84] .