Comparison of the antioxidant properties of emu oil with other avian oils

Abstract

The antioxidant properties of emu oil were compared with oils derived from the fat of other avian species. We first examined their free radical scavenging activity against the 2,2-diphenyl-1-picryl hydracyl radical. The concentration of emu oil in the test solution that caused 50% neutralisation (IC50) was variable (24.5 ± 5.9 mg/mL, range 5.3–55.4 mg/mL), but similar to values obtained for other ratites (10.7 ± 5.9 mg/mL). In contrast, the IC50 values for duck and chicken oil were much higher (118.0 ± 8.1 mg/mL). The variability in the radical scavenging activity of emu oil preparations may reflect variations in the diets of the birds, the processing protocol and/or the storage age of the oil. We also evaluated some of the ratite oils for their inhibitory capacity on human erythrocyte membrane oxidation, by measuring the reduction of the thiobarbituric acid-reactive substance (TBAR) production. Emu oil had a greater effect in decreasing TBAR production than either the ostrich or rhea oil, suggesting that it offers more protection than the other ratite oils against oxidative damage. In conclusion, we demonstrated that emu oil has both antioxidant properties in vitro and a protective role against oxidative damage in a model biological membrane system. The antioxidant or radical scavenging properties of emu oil appear to be due to minor constituents in the non-triglyceride fraction of the oil, while its high ratio of unsaturated to saturated fatty acids (UFA : SFA) offers protection against oxidative damage.