Coenzyme Q10 and melatonin protect cryopreserved equine sperm against lipoperoxidation

The objective of the experiment was to evaluate the effect of the addition of different concen-trations of the antioxidants Coenzyme Q10 (CoQ10) and melatonin to equine semen freezing diluent, alone or in combination, during the cryopreservation process. Twenty ejaculates (n = 5 stallions) were divided in groups: Control (C, without the addition of antioxidants), melatonin 0.75 mM (MEL1), melatonin 1.5 mM (MEL2), CoQ10 40 mu g/mL (Q1), CoQ10 200 mu g/mL (Q2), and CoQ10 40 mu g/mL+ 0.75 mM melatonin (Q1 +MEL1). Q1 and Q2 groups demonstrated intact plasma membrane and high mitochondrial membrane potential after 30 (M-30) and 60 (M-60) min of incubation compared with the control group (Q1: 64.8 % & PLUSMN; 9.9 %, Q2: 65.2 % +/- 10.5 %, C: 55.1 %+/- 10.0 %; M-30 and Q1: 63.3 %+/- 10.4 %, Q2: 64.6 %+/- 10.8 %, C: 53.1 & PLUSMN; 10.6 %; M-60; P < 0.05). Melatonin conferred greater membrane stability at all evaluated times compared with the control group (MEL1: 42.1 % +/- 6.0 %; MEL2: 44.0 % +/- 6.7 %, C: 35.9 % +/- 5.9 %; M-0; MEL1: 40.8 +/- 5.6 %; MEL2: 42.6 %+/- 7.2 %, C: 33.1 +/- 6.6 %; M-30 and MEL1: 37.5 +/- 7.4 %; MEL2: 39.1 %+/- 7.2 %; C: 31.3 % & PLUSMN; 6.5 %; M-60; P < 0.05). The use of antioxidants alone or in combination resulted in lower levels of lipoperoxidation at all times evaluated compared with in the control group (P < 0.05). In conclusion, CoQ10 and melatonin were effective in the cryopreservation of equine semen by decreasing lipoperoxidation and promoting a higher per-centage of spermatozoa with a high mitochondrial potential, total and progressive motility, and prevention of membrane lipid disorder.