The n-butanol extract of Polygonatum sibiricum improves spleen aging via p53 pathway.

BACKGROUND

Aging affects the function of multiple organs, including the spleen, which undergoes age-related structural changes and functional decline. Polygonatum sibiricum, a traditional anti-aging herbal medicine, contains saponins as its primary active components. However, the potential effects and underlying mechanisms of Polygonatum n-butanol extract (PNBE), which is rich in saponins, on splenic aging remain to be elucidated.

PURPOSE: This study aimed to investigate the effects and molecular mechanisms of PNBE on splenic aging.

METHODS

PNBE was prepared by n-butanol extraction to obtain a high concentration of saponins, and its main components were identified using UPLC-Q-TOF/MS. Naturally aged mice were treated with PNBE, after which splenic morphology, aging markers, and DNA damage were assessed. Flow cytometry was employed to analyze splenic lymphocyte subsets, proliferation capacity, cell cycle distribution, and apoptosis. Transcriptomic analysis was performed to identify potential target pathways, and the p53 signaling pathway was verified by WB and qRT-PR analyses.

RESULTS

PNBE, primarily containing saponins, aldehydes, and glycosides, significantly improved splenic morphological alterations, attenuated DNA damage, and suppressed the mRNA expression of aging-related genes p21 Cip1/Wαf1, p16 INK4α, and p19 Arf in aged mice. PNBE also increased the proportion of naive T cells, reduced the percentage of cells arrested in G1 phase, enhanced T/B lymphocyte proliferation, and decreased late apoptotic cell populations, thus maintaining splenic lymphocyte homeostasis. Transcriptomic analysis revealed that the p53 signaling pathway likely mediates PNBE's anti-aging effects in the spleen. Further validation demonstrated that PNBE inhibited p53 protein phosphorylation and regulated the expression of downstream genes including Cdk2, Gadd45, Bax, and Bcl-2.

CONCLUSIONS

PNBE delays splenic aging by inhibiting the p53 signaling pathway and regulating downstream cell cycle and apoptosis-related gene expression, thereby alleviating cell cycle arrest, proliferation inhibition, and excessive apoptosis in splenic lymphocytes.