Finger Citron ( <i>Citrus medica</i> L. var. <i>sarcodactylis</i> Swingle) and Its Characteristic Component Limettin Alleviated Diet-Induced Obesity via Modulating Gut Microbiota and Steroid Hormone Biosynthesis

This study investigated the antiobesity effects and underlying mechanisms of finger citron extract (FC) and its characteristic compound limettin (LMT) in high-fat diet (HFD)-induced obese mice. FC and LMT significantly reduced body weight gain and improved glucose and lipid homeostasis in obese mice. Fecal 16S rRNA sequencing revealed that both treatments reversed HFD-induced gut dysbiosis, enriching <i>norank_f__norank_o__Clostridia_UCG-014</i>, while FC uniquely increased <i>Akkermansia</i> and decreased <i>Rikenella</i>. Serum metabolomics indicated that FC and LMT markedly activated the steroid hormone biosynthesis pathway, elevating 11β-hydroxyprogesterone, 17α-hydroxyprogesterone, and 11-deoxycorticosterone. Colon transcriptomics further confirmed altered local steroid synthesis and metabolism in the colon. Antibiotic depletion and fecal microbiota transplantation verified the indispensable role of gut microbiota in FC/LMT-mediated metabolic protection. Collectively, FC and LMT ameliorated diet-induced obesity by modulating steroid hormone biosynthesis through gut microbiota regulation, highlighting their potential as functional dietary supplements for obesity prevention.