Exploration of glucose lowering ability of Moringa oleifera polysaccharide in simulated intestinal and liver environment: an integrated in vitro investigation of its prebiotic potential, intestinal transport, and hepatic insulin-resistance-related response.

Abstract

Moringa oleifera leaf polysaccharide (MOLP) is a dietary fiber with hypoglycemic activity, but the relationships among its microbial fermentation, epithelial transport, and hepatic effects remain unclear. Here, an integrated in vitro platform comprising pooled human fecal fermentation, bifidobacterial monoculture assays, Caco-2 transepithelial transport, and insulin-resistant HepG2 cells was used to investigate a potential gut-liver axis mediated by MOLP. Compared with commercial larch arabinogalactan and inulin, MOLP showed a relatively gradual fermentation profile and was associated with increased growth of the tested Bifidobacterium strains. During fermentation, arabinose decreased preferentially, while propionate and butyrate accumulated. These short-chain fatty acids showed favorable predicted binding affinities for GPR41/GPR43. After Caco-2 transport, carbohydrate equivalents and several fatty acids were detected in the basolateral medium, indicating transepithelial passage in vitro rather than systemic bioavailability. The resulting permeate increased glucose consumption and glycogen-associated PAS staining in insulin-resistant HepG2 cells. These effects were accompanied by reduced TLR4 and MyD88 abundance, decreased NF-κB phosphorylation, and increased AMPK and IRS1 phosphorylation, SIRT1 expression, and PI3K/AKT1 signaling. Collectively, this study provides evidence supporting the glucose lowering ability of MOLP in simulated intestinal and liver environment and a potential mechanistic cascade linking microbial utilization, intestinal translocation, and hepatic insulin resistance.