Inducing a synergistic anti-obesity effect by increasing the bioavailability of the flavonoid rutin with a L. plantarum strain.

Rutin, a sugar-bonded flavonoid, exhibits anti-obesity potential but has limited bioavailability unless hydrolyzed to isoquercetin or further to quercetin. This study evaluated Lactiplantibacillus plantarum HAC03 (HAC03), isolated from Korean white kimchi, as an effective facilitator of rutin bioavailability. HAC03 rapidly converted rutin into isoquercetin and, at a slower rate, to quercetin both in vitro and in vivo. Unlike HAC03-only or rutin-only groups, co-administration of HAC03 and rutin synergistically reduced body weight, adipocyte size, and obesity biomarkers by suppressing fat synthesis and enhancing fatty acid β-oxidation in diet-induced obese mice. HAC03, together with rutin, colonized the ileum and enriched polyphenol-metabolizing gut microbes. At 30 min post-administration, isoquercetin-more bioavailable and effective than its precursor, rutin-peaked (∼9 μM) in mouse portal vein blood, while remaining minimal or undetectable in controls. This pairing of functional flavonoid and tailored probiotic synergistically combats obesity via ileal isoquercetin conversion, offering a promising single-flavonoid, single-probiotic obesity-management strategy.