Naringenin and Hesperetin Alleviate Hepatic Aging Through Coordinated Modulation of Persulfidation, Senescence, and Nrf2/Sirt1 Signaling in Old Rats.

Naringenin (NAR) and hesperetin (HES) are citrus flavanones that have been shown to exert various geroprotective effects. However, key regulators of these processes remain unexplored. To address this gap, we investigated the mechanisms through which NAR and HES modulate hepatic redox control, persulfidation, and senescence-associated pathways in 24-month-old male Wistar rats. Animals were treated orally with NAR or HES (15 mg/kg b.w.) for 4 weeks, while control groups remained physiologically intact or received vehicle. Liver tissue was analyzed using a dimedone-based switch method to evaluate overall protein persulfidation (P-SSH), Western blot, qPCR, and histological analysis, including quantification of IHC staining and IF labeling. Our results showed that both citrus flavanones increased total P-SSH levels while exerting distinct regulatory effects on the H2S metabolic network. Only HES upregulated gene expression of H2S-producing enzymes (cystathionine beta-synthase CBS, cystathionine gamma-lyase CSE, and mercaptopyruvate sulfurtransferase MST) and catabolic enzymes (sulfide:quinone oxidoreductase SQR and thiosulfate sulfurtransferase TST), together with CBS protein, whereas NAR decreased CSE protein expression. Both NAR and HES treatment activated the Nrf2 signaling pathway, as evidenced by increased nuclear translocation of Nrf2 in the treated groups. Concurrently, NAR and HES increased Sirt1 expression, which was accompanied by decreases in p16 and β-galactosidase expression, indicating attenuation of hepatic senescence. Together, these findings highlight a synergistic interplay among persulfidation, H2S metabolism, and Nrf2/Sirt1 signaling as a key mechanism by which citrus flavanones support hepatic resilience during aging.