Apigenin-6-C-glucoside ameliorates MASLD in rodent models via selective agonism of adiponectin receptor 2

Abstract

Adiponectin plays key roles in energy metabolism and ameliorates inflammation, oxidative stress, and mitochondrial dysfunction via its primary receptors, adiponectin receptors -1 and 2 (AdipoR1 and AdipoR2). Systemic depletion of adiponectin causes various metabolic disorders, including MASLD; however adiponectin supplementation is not yet achievable owing to its large size and oligomerization-associated complexities. Small-molecule AdipoR agonists, thus, may provide viable therapeutic options against metabolic disorders. Using a novel luciferase reporter-based assay here, we have identified Apigenin-6-C-glucoside (ACG), but not apigenin, as a specific agonist for the liver-rich AdipoR isoform, AdipoR2 (EC₅₀: 384 pM) with >10000X preference over AdipoR1. Immunoblot analysis in HEK-293 overexpressing AdipoR2 or HepG2 and PLC/PRF/5 liver cell lines revealed rapid AMPK, p38 activation and induction of typical AdipoR targets PGC-1α and PPARα by ACG at a pharmacologically relevant concentration of 100 nM (reported cMax in mouse; 297 nM). ACG-mediated AdipoR2 activation culminated in a favorable modulation of key metabolic events, including decreased inflammation, oxidative stress, mitochondrial dysfunction, de novo lipogenesis, and increased fatty acid β-oxidation as determined by immunoblotting, QRT-PCR and extracellular flux analysis. AdipoR2 depletion or AMPK/p38 inhibition dampened these effects. The in vitro results were recapitulated in two different murine models of MASLD, where ACG at 10 mg/kg body weight robustly reduced hepatic steatosis, fibrosis, proinflammatory macrophage numbers, and increased hepatic glycogen content. Together, using in vitro experiments and rodent models, we demonstrate a proof-of-concept for AdipoR2 as a therapeutic target for MASLD and provide novel chemicobiological insights for the generation of translation-worthy pharmacological agents.

Keywords: AdipoR2 agonist; Adiponectin receptor; Apigenin-6-C-Glucoside; Isovitexin; MASLD; NAFLD; NASH.