Quercetin and rutin: effects of two flavonoids on induced oxidative stress in human ejaculated sperm

Quercetin (Q) and rutin (R) are two natural flavonoids with antioxidant properties. We evaluated the toxicity of Q and R at 20μM, 30μM, 50μM, 100μM, 200μM, 400μM in swim up selected human sperm. The antioxidant activity (Q and R 20μM and 30μM) was tested on lipid peroxidation (LPO) induced by tert-butylhydroperoxide in human sperm. LPO was evaluated using the C11-BODIPY581/591 probe and sperm structural damages were assessed by transmission electron microscopy in samples incubated with and without Q and R. A significant dose dependent toxic effect was observed for both compounds on sperm viability (Q and R: r= -0.98 P<0.001), on sperm progressive motility (Q: r=-0.98, R: r=-0.97; P<0.001), and on non progressive motility (Q; r=-0.58, P<0.01; R: r=-0.50, P<0.05). Both flavonoids, used at 20μM and 30μM, showed antioxidant properties on LPO induced in human sperm and a general protective effect against ultrastructural damages of LPO. In conclusion, we observed that Q exhibited a little higher toxicity than R; on the other hand R is little low protective on induced LPO. Our preliminary results demonstrated the scavenger properties of these flavonoids in vitro on human sperm. Keywords: human sperm, lipid peroxidation, quercetin, rutin, TEM