Hepatoprotective effects of hydroxysafflor yellow A in D-galactose-treated aging mice

Hydroxysafflor yellow A (HSYA) is an effective chemical component isolated from Chinese herb Carthamus tinctorius L. In present study, we aimed to evaluate the effects of HSYA on D-galactose- (D-gal-) induced aging in mice, and to elucidate the underlying mechanism. Male C57BL/6 mice were intraperitoneal injection of D-gal and HSYA for 8 weeks. The body weight gain, spleen and thymus coefficients were determined. Levels of super dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) in serum and liver were measured using commercial kits. Pathological changes and the SA-β-Gal activity in liver tissues were detected by hematoxylin and eosin and SA-β-Gal staining. The expression levels of p16, CDK4, CDK6 and phosphorylation levels of Retinoblastoma (Rb) were detected by immunohistochemistry and western blot analysis. mRNA levels of genes regulated by p16-Rb pathway were determined by quantitative real-time PCR. In vivo, HSYA improved the aging changes including body weight, organ index and antioxidant status such as activities of SOD, CAT, GSH-Px and MDA in D-gal treated aging mice. HSYA also dramatically attenuated pathologic changes of aging liver tissues induced by D-gal. Furthermore, HSYA significantly decreased the mRNA and protein level of cyclin-dependent kinase inhibitor p16, followed by increasing CDK4/6 protein expression and decreasing the phosphorylation of Retinoblastoma (pRb) which up-regulated the expression of downstream genes CCNE1, CCNA2, P107 and MCM4. Collectively, these data indicated that HSYA could ameliorate aging, especially hepatic replicative senescence resulting from D-gal, the mechanism could be associated with the suppression of p16-Rb pathway.