Bioactive flavonoids from Ohwia caudata stems influence small intestinal motility ex vivo

This study reveals the therapeutic potential of Ohwia caudata in treating diarrhea-predominant irritable bowel syndrome (IBS-D), with a focus on its flavonoid constituents and their multimodal mechanisms. Forty flavonoids were identified, twelve of which are newly reported. Among these, twelve active compounds markedly suppressed intestinal contraction through distinct pathways: one (compound 21) acted as a calcium channel blocker, while others functioned via nitric oxide synthase activation (compounds 9, 10, and 23) or alternative mechanisms (compounds 25 and 29). Key structural determinants of activity were established: prenyl substitution on the A-ring and a 4'-OH group enhanced efficacy, whereas glycosylation generally reduced it. Stability studies further highlighted the role of C-3 glycosylation in configuring the physicochemical behavior of prenylated dihydroflavonols. These results provide a mechanistic basis for the traditional use of O. caudata in gastrointestinal disorders and offer valuable insights for the development of flavonoid-based IBS-D therapeutics.