Antioxidant activity and mechanism of inhibitory action of gentisic and α-resorcylic acids
Azadeh Mardani-Ghahfarokhi, Reza Farhoosh
Abstract
Abstract The antioxidant activity of gentisic (GA) and α-resorcylic (α-RA) acids was investigated by considering their molecular structures in various oxidative environments, including DPPH · scavenging assay, stripped olive and soybean oils, and the corresponding oil-in-water emulsions. The mechanism of action in the oils was evaluated in the presence of different concentrations of the antioxidants at 60 °C, using the kinetic parameters the stabilization factor ( F ), the oxidation rate ratio (ORR), the activity ( A ), and the average rate of antioxidant consumption ( $$\overline{r}_{{{\text{AH}}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mover> <mml:mi>r</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mtext>AH</mml:mtext> </mml:msub> </mml:math> ). GA was significantly more potent antioxidant than α-RA in all the environments. Although the less polar α-RA showed better activity in the emulsions rather than in the bulk oils, GA with an ortho -hydroxy structure had higher capacity to scavenge DPPH · , and LOO · in the oils and emulsions. The lower performance of α-RA was attributed to its participation in side reactions of chain initiation (AH + LOOH → A · + L · + H 2 O) and propagation (A · + LH → AH + L · ) as competed with the main chain termination reaction (LOO · + AH → LOOH + A · ).