Effects Of Flavonoids From Cuscuta Chinensis On Human Sperm Viability

In recent years,as people's lifestyles change,the incidence of infertility increases.According to statistics,male infertility accounts for 30-50%of infertility cases.Poor sperm quality,low numbers,abnormal morphology,and low sperm motility are important causes of infertility.As a traditional Chinese medicine,Cuscuta chinensis has the effect of nourishing kidney and securing essence.The water extract from Cuscuta chinensis has protective effect on sperm cells.However,it is unclear what components in the extract are really functional.In this study,we aim to investigate the effect of flavonoids from Cuscuta chinensis on human sperm.The effects of isorhamnetin,quercetin,astragalin,hyperoside,and kaempferol on the viability of human sperm cells were tested.Quercetin,astragalin,and hyperoside were found to be effective.Main results are as follows:1.Human sperms were treated with different concentrations of quercetin.After 12 h of culture,the total viability of sperm decreased by 1.45 fold and 1.97 fold at 200?M and 400?M,respectively.The acrosome reaction and capacitation of spermatozoa induced by progesterone decreased by 1.73 fold and 2.02 fold,respectively.The acrosome reaction and capacitation of spermatozoa decreased with 100?M quercetin treatment.The higher concentration of quercetin,the more obvious decrease was,indicating that 100?M and above quercetin may disrupt progesterone signaling pathways.When the quercetin concentration was 50?M,the intracellular Ca2+concentration decreased.The higher the concentration,the more obvious the decrease was,suggesting that quercetin inhibits sperm cell function by reducing the intracellular Ca²⁺concentration.Tyrosine phosphorylation has become an important factor in regulating sperm function.Tyrosine phosphorylation levels were reduced at quercetin concentrations of 100-400?M in a dose-dependent manner.These results show that quercetin inhibits sperm capacitation and acrosome reaction via low calcium-induced tyrosine kinase inactivation.2.Treatment of sperms with different concentrations of astragalin.The results showed that the progressive motility and linearity of human sperms increased by 1.23 fold and 1.17 fold,respectively.The progressive motility of weak sperms increased by 1.41 fold.The progressive motility of severely weak sperms increased by 2.18 fold and 2 fold at 1×10^-44 mol/L and 1×10^-5mol/L,respectively.Astragalin has little effect on the curvilinear velocity and straight line velocity of human sperms.The acrosome reaction and capacitation level increased by 1.23 fold and 1.38fold,respectively.The intracellular Ca²⁺concentration also increased,suggesting that astragalin enhances human sperm function through increasing intracellular Ca²⁺concentration.In sperm capacitation and acrosome reaction,increased level of protein kinase A?PKA?induces tyrosine phosphorylation.In our study,tyrosine levels were increased but there was no change in the protein kinase A?PKA?level,indicating that protein kinase A did not induce increased tyrosine levels.In contrast,the proline-rich tyrosine kinase 2?PYK2?level was increased,indicating that increased intracellular Ca²⁺activates PYK2,resulting in increased tyrosine levels.3.Treatment of human sperm with different concentrations of hyperoside.At the concentration of 1×10^-55 M hyperoside,the progressive motility,curvilinear velocity and straight line velocity increased by 1.34 fold,1.28 fold and 1.41 fold,respectively.The acrosome reaction and capacitation level also increased by 1.75 fold and 1.51 fold,respectively.Hyperoside had no effect on intracellular Ca²⁺.So further investigation is needed to elucidate the mechanism.In summary,single flavonoids from Cuscuta chinensis such as astragalin and hyperoside promote sperm motility.However,excessive quercetin inhibits sperm motility.These results verified the complexity of active substances in traditional Chinese herbs.The study on the medicinal mechanism of the active substances from Cuscuta chinensis may provide the theoretical basis for the development of the active products from Cuscuta.