Gut microbiota-derived isoxanthohumol metabolite, 8-prenylnaringenin, mitigates endothelial dysfunction in...

Humulus lupulus L. (hops), which is traditionally used in brewing, is a rich botanical source of prenylated flavonoids with potential cardiovascular protective properties. Of these, 8-prenylnaringenin (8-PN), a potent phytoestrogen formed from isoxanthohumol by the gut microbiota, has been implicated in vascular health. Nitric oxide (NO), which is produced by endothelial nitric oxide synthase (eNOS), exerts profound effects on vascular tone and endothelial integrity. This study examined the protective effects of 8-PN on endothelial signaling and vascular function using in vitro endothelial cell assays, ex vivo isolated artery preparations, and an in vivo mouse model of Angiotensin II (Ang II)-induced endothelial dysfunction. In endothelial cells, 8-PN increased phosphorylation of eNOS on Ser1177 and NO production through G-protein coupled estrogen receptor (GPER)-mediated Ca²⁺-dependent signaling pathways involving phosphorylation of Ca²⁺/calmodulin-dependent protein kinase β (CaMKKβ) and AMPK-activated protein kinase (AMPK). Furthermore, 8-PN activated eNOS via GPER-mediated epidermal growth factor receptor (EGFR) activation, with c-Src facilitating phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) and extracellular signal-related kinase (ERK) phosphorylation. Molecular docking results indicated that 8-PN could bind to GPER and facilitate the activation of downstream signaling cascades. Both of 8-PN-mediated eNOS phosphorylation are mediated through the Gβγ subunit. In vivo, 8-PN attenuated angiotensin II-induced endothelial dysfunction in mice and induced vasorelaxation in vivo. 8-PN stimulated eNOS phosphorylation and NO production via dual GPER-dependent pathways, supporting its potential as a therapeutic candidate for endothelial dysfunction-related vascular diseases.