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

Flavonoids, plant-derived compounds, are broadly categorized into glycoside (sugar-bonded) and aglycone (sugar-removed) forms and are predominantly found as glycosides in nature. Rutin, a glycoside, is a widely recognized flavonoid with significant potential as an anti-obesity agent. However, its low bioavailability in the body presents challenges in obesity treatment. We aimed to enhance the bioavailability and anti-obesity effect of rutin through microbial involvement. Lactiplantibacillus plantarum HAC03, one of the candidates, demonstrated the ability to hydrolyze rutin into isoquercetin and quercetin in vitro. In a diet-induced obesity mouse model, the combination of rutin and the L. plantarum strain resulted in significant weight loss, reduced adipocyte size and lowered obesity-related biomarkers in the blood, decreased fat-synthesis related gene expression, and increased fatty acid {beta}-oxidation related gene expression compared to other test groups. This includes groups treated with rutin or quercetin alone or in combination with a different species from the same Lactobacillus genus, known for its anti-obesity effect but lacking the ability to hydrolyze rutin. This synergistic combination also alleviated insulin resistance and reduced fat in the liver. Gut microbiota analysis revealed localization of L. plantarum in the ileum and beneficial changes in disrupted microbiota in the intestine. These findings provide insights into underlying mechanisms causing the synergistic effect and suggest a novel combination that is as safe as microbial monotherapies with L. plantarum or L. rhamnosus but more effective in anti-obesity treatment.