Ellagitannin Component Punicalin Ameliorates Cognitive Dysfunction, Oxidative Stress, and Neuroinflammation via the Inhibition of cGAS-STING Signaling in the Brain of an Aging Mouse Model.

Abstract

Despite remarkable breakthroughs in pharmacotherapy, many potential therapies for aging remain unexplored. Punicalin (PUN), an ellagitannin component, exerts anti-inflammatory, antioxidant, and anti-apoptotic effects. This study investigated the beneficial effects of PUN against age-related brain damage in mice and explored the underlying mechanisms. We validated the protective effects of PUN against D-galactose (D-gal)-induced neuroinflammation and subsequent neuronal damage in BV2 microglia and N2a cells, respectively, in vitro. In vivo experiments were conducted on mice that were administered an 8-week regimen of intraperitoneal injections of D-gal at a dosage of 150 mg/kg/day, concurrently with oral gavage of PUN at the same dose. PUN inhibited the production of D-gal-induced inflammatory cytokines (iNOS, COX2, TNF-α, IL-6, IL-2, and IL-1β) in BV2 cells and conferred protection to N2a cells against synaptic damage mediated by BV2 microglia-induced neuroinflammation. The in vivo findings revealed that PUN considerably improved memory and learning deficits, reduced MDA levels, enhanced GSH-Px, CAT, and SOD activities, and modulated the expression of inflammatory proteins such as iNOS, COX-2, IL-1β, IL-2, IL-6, and TNF-α. Furthermore, PUN inhibited the secretion of SASP factors (ICAM-1, PAI-1, MMP-3, and MMP-9), decreased microglial activation, and reduced astrocytosis. Additionally, PUN suppressed the expression of cGAS, p-STING, p-TBK1, p-p65, and p-IRF3 in aging mouse brains and cultured BV2 microglia. In conclusion, PUN improved cognitive dysfunction in aging mice through antioxidant and anti-inflammatory mechanisms via inhibition of the cGAS-STING pathway, suggesting that it can be a promising therapeutic agent for brain aging and aging-related diseases.