Effect of PUFAs-ω3 and ω6 on oxidative stress of sheep erythrocytes.

Background: In recent years, the use of long-chain polyunsaturated fatty acids (PUFA) ω3 and ω6, as food supplements in livestock has increased due to their beneficial properties related to their antioxidant activity. It has been demonstrated however that a high intake of these substances has prooxidant and cell-damaging effects, especially if their circulating concentrations are unbalanced. Starting from these premises, and taking advantage of previous findings, the present study aimed at defining the optimal circulating concentrations and PUFAs ω3/ω6 ratio, to ensure the antioxidant/oxidant balance in sheep RBCs.

Results: All tested concentrations (25-300 µg/mL in PBS) of PUFAs-ω3 after 4 h of treatment on sheep RBCs, showed antioxidant properties with a significant decrease in reactive oxygen species (ROS) versus the control group (CTRL) (p < 0.05). Furthermore, ω6 showed an antioxidant effect at low concentrations (25-200 g/mL) but a pro-oxidant effect at the highest concentrations (250 and 300 µg/mL) with a significant increase in ROS production (123.6 ± 2.1 and 131.4 ± 6.5% sloope RFU of CTRL respectively p < 0,001), malondialdehyde (MDA) (p < 0.01), and haemolysis (p < 0.01) versus CTRL group (1.1 ± 0.1%), and, also with a decrease of Trolox equivalent antioxidant capacity (TEAC) (p < 0,05). The ratio ω3/ω6 of 1:10 (25/250 µg/mL) and 1:4 (25/100 µg/mL) showed an intracellular ROS level like the CTRL group whereas, the ratio 1:2 (100/200 µg/mL) resulted in a significant decrease in ROS production (62.71 ± 2.31% slope RFU of CTRL, p < 0.001) and MDA (p < 0.001), with an increase in TEAC (p < 0.05), and a decrease haemolysis versus the control group (p < 0,01).

Conclusions: Our results showed that a beneficial effect on the oxidative state of sheep RBCs was obtained with in vitro administration of low concentrations of ω6 and with all tested concentrations of ω3. The addition of ω6 at high concentrations leads to an imbalance in the PUFA ω3/ω6 ratio, compromising the oxidative state and viability of the RBCs. The maximum antioxidative effect was found at ω3/ω6 ratio 1:2).