Hesperetin is a potent bioactivator that activates SIRT1-AMPK signaling pathway in HepG2 cells

Sirtuin 1 (SIRT1) is a deacetylase enzyme that plays crucial roles in controlling many cellular processes and its downregulation has been implicated in different metabolic disorders. Recently, several polyphenols have been considered as the effective therapeutic approaches that appear to influence SIRT1. The main goal of this study was to evaluate the effect of hesperetin, a citrus polyphenolic flavonoid, on SIRT1 and AMP-activated kinase (AMPK). HepG2 cells were treated with hesperetin in the presence or absence of EX-527, a SIRT1 specific inhibitor, for 24h. Resveratrol was used as a positive control. SIRT1 gene expression, protein level, and activity were measured by RT-PCR, Western blotting, and fluorometric assay, respectively. AMPK phosphorylation was also determined by Western blotting. Our results indicated a significant increase in SIRT1 protein level and activity as well as an induction of AMPK phosphorylation by hesperetin. These effects of hesperetin were abolished by EX-527. Furthermore, hesperetin reversed the EX-527 inhibitory effects on SIRT1 protein expression and AMPK phosphorylation. These findings suggest that hesperetin can be a novel SIRT1 activator, even stronger than resveratrol. Therefore, the current study may introduce hesperetin as a new strategy aimed at upregulation SIRT1-AMPK pathway resulting in various cellular processes regulation.