Mung bean ( <i>Vigna radiata</i> L.) ethanol extract alleviates alcoholic liver injury with modulation of the gut microbiota and spermidine elevation

The pathophysiology of alcohol-associated liver disease (ALD) is multifaceted. Utilizing the gut-liver axis framework and integrated multi-omics approaches, this study systematically evaluated the therapeutic potential of mung bean (<i>Vigna radiata</i> L.) ethanol extract (MBE) in ALD and its regulatory effects on the gut microbiota and serum metabolites. Chemical analysis identified vitexin, isovitexin, catechin, trigonelline, and caffeic acid as MBE's primary bioactive compounds. In a modified NIAAA model, MBE alleviated liver injury, lipid dysregulation, inflammation, oxidative stress, and gut barrier damage <i>via</i> PPARα-mediated lipid metabolism and Nrf2-driven antioxidant activation. 16S rRNA sequencing and an <i>in vitro</i> fermentation experiment revealed that MBE specifically enriched <i>Lactobacillus johnsonii in vivo</i> and promoted its growth <i>in vitro</i>, with this bacterium being closely associated with increased spermidine levels. <i>Lactobacillus johnsonii</i> supplementation replicated MBE's hepatoprotection by increasing spermidine and mitigating alcohol-induced hepatic/intestinal damage. Subsequent <i>in vivo</i> and <i>in vitro</i> spermidine interventions further validated its hepatoprotection. These findings propose a novel "MBE-<i>Lactobacillus johnsonii</i>-spermidine-liver" regulatory mode, positioning MBE as a dietary or therapeutic candidate for ALD and offering gut-liver axis targets.