Effect of lycopene on biomarkers of oxidative stress in rats supplemented with ω−3 polyunsaturated fatty acids

Eicosapentaenoic (C20:5 n−3, EPA) and docosahexaenoic (C22:6 n−3, DHA) fatty acids are highly susceptible to lipid oxidation and may contribute to oxidative stress. The purpose of this study was to evaluate if a diet rich in EPA and DHA could promote higher oxidation in both plasma and brain tissue of rats and if lycopene supplementation could revert the oxidation biomarkers to their baseline levels. Wistar rats were divided into four groups (7 rats/group): SOY group received AIN93M diet containing 8% soybean oil for 21 days; OMEGA group received 8% fish oil containing 2% EPA and 1% DHA instead of soybean oil for 21 days; OMEGA-L0.5 and OMEGA-L50 groups were fed a diet containing 8% fish oil for 11 days followed by lycopene supplementation (5 and 500mg/kg diet, respectively) for 10 more days. The brain homogenate oxidation measured by TBARS suggested that supplementation with EPA and DHA reduced the oxidation rate and this effect was suppressed by lycopene at both concentrations. Antioxidant capacity measured by DPPH method in plasma of groups supplemented with EPA and DHA was nil while in SOY group it was 21.4%. Lycopene was not detected in the plasma of the animals. It is likely that antioxidants present in plasma have been depleted to keep malondialdehyde concentration measured by TBARS unchanged. Both plasma malondialdehyde concentration and antioxidant activity of groups with and without lycopene supplementation did not differ. Hence, diets rich in EPA and DHA did not promote higher oxidation in rat brain homogenate but reduced plasma antioxidant capacity. Lycopene did not show antioxidant plasma protection at both doses. Taking into account that plasma α-tocopherol concentration did not change among the groups and that rats synthesize ascorbic acid, additional research should be carried out to identify the oxidative results observed in this study.