Regulatory effects mediated by ulvan oligosaccharide and its zinc complex on lipid metabolism in high-fat diet-fed mice

Obesity-induced lipid metabolism disorders are risk factors for hyperlipidemia, atherosclerosis, and nonalcoholic fatty liver disease. Seaweed oligosaccharides and Zn supplements are potential alternatives to alleviate obesity. Herein, ulvan oligosaccharide (UO) was used as a ligand to prepare a novel Zn supplement (UO-Zn). Subsequently, we explored potential mechanisms underlying UO- and UO-Zn-mediated improvements in lipid metabolism in mice fed a high-fat diet. We found that UO enhanced the abundance of key species (Blautia and Turicibacter) and functions (glycolytic, pentose phosphate, and histidine/lysine biosynthesis pathways) in the gut microbiota, thereby increasing the production of short-chain fatty acids and activating AMPK. Accordingly, UO treatment regulated the transcription of lipid metabolism genes, including ACOX1, ACC, and FASN, thereby reducing blood lipid levels and hepatic lipid accumulation. Zn could act synergistically with UO, enhancing the reversal of cholesterol transport and fatty acid beta-oxidation via the MTF1/PPAR alpha pathway, markedly reducing body and adipose tissue weights.