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

Miguel, Maria Graça

Another method to evaluate antioxidant ability is based on the reduction of Fe 3+ to Fe 2+ in which the yellow colour of the test solution changes to various shades of green and blue, depending on the reducing power of each sample. The presence of reducing agents causes the conversion of Fe 3+ /ferricyanide complex to the ferrous form that may be followed at 700 nm due to the formation of Perl's Prussian blue Fe 4 [Fe(CN) 6 ] 3 . Increasing absorbance at 700 nm indicates an increase in reductive ability [44] . Several authors along with other antioxidant activity assays also tested the reducing power of the essential oils of Himalayan Lauraceae species [44] , Myrtus communis var. italica [46] , Hymenocrater longiflorus [47] , Origanum onites L. [82] and Psammogeton canescens [49] . In this case, the antioxidant activity measured by the β-carotene bleaching and DPPH tests showed weak activity. The authors attributed such activity to the low concentration of phenolic compounds present in the essential oils, nevertheless the reducing power of the same samples is similar to that of the reference ascorbic acid, mainly at higher concentrations [49] .