Polygonatum sibiricum polysaccharide attenuates cyclophosphamide-induced testicular damages and sperm defects in male mice via Nrf2 mediating antioxidant protective mechanisms.

Polygonatum sibiricum polysaccharides are gaining more attention with various pharmacological activities, including anti-inflammatory and antioxidant. However, whether Polygonatum sibiricum polysaccharides could be a therapeutic modality for male infertility is not clear. Herein, a water-soluble Polygonatum sibiricum polysaccharide (PSPs-1) was isolated by a novel semi-biomimetic cellulase hydrolysis method and its effects and mechanism of action in improving cyclophosphamide-induced testicular damages in mice and H2O2-induced oxidative damage in normal mouse testis sertoli cells (TM4) were investigated. Results revealed that PSPs-1 was constituted of the residues including fructose, mannose, and glucose with an average molecular weight of 1.6048 × 105 Da. The scavenging rate of hydroxyl radical free radical in vitro reached 97.70 ± 0.93 %. Next, 200 μg/mL PSPs-1 treatment could increase the cell viability of TM4 cells by 37.9 %. Oral administration of 150 mg/kg PSPs-1 could increase the sperm count by 70.27 % and significantly improve the sperm quality in testicular-damaged mice. Furthermore, the mechanism study suggests that the protection of PSPs-1 on reproductive injury was partially mediated by the activation of Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2). Treatment with PSPs-1 increased the Nrf2 protein expression, which leads to up-regulated expression of a series of Nrf2 target genes, including Glutathione Peroxidase 4 (GPX4) and NAD(P)H:quinone oxidoreductase 1 (NQO1). Subsequently, the contents of antioxidant enzymes were enhanced, but the levels of lipid peroxidation products were reduced in cells and testes. Overall, our study provides a basis for developing PSPs-1 into a valuable functional food ingredient or alternative therapeutic modality that can alleviate testicular damages.