Comparison of in vivo glycolipid metabolism regulation pathway of lotus leaf polysaccharide and its combination with flavonoids and alkaloids: effectiveness of high-pressure homogenization-assisted dual enzyme extraction

Lotus leaf is an optimal raw material for the preparation of foods with the function of regulating glycolipid metabolism. However, further investigation is required to elucidate the synergistic regulatory effects of lotus leaf polysaccharides (LLP), flavonoids, and alkaloids, which act as the main active components in lotus leaves. This study optimally prepared LLP and whole functional components (LLE) containing LLP, flavonoids and alkaloids by high-pressure homogenization-assisted dual enzyme extraction with and without pre-/post treatment. LLP and LLE exerted regulatory roles in glycolipid metabolism and alleviated liver, kidney, and pancreas damages of db/db mice. LLP was utilized by gut bacteria, promoting the production of beneficial metabolites i.e. lithodeoxycholic and butyric acids, which reached the liver through blood circulation, activating insulin signaling, and regulating glycolipid metabolism. The combination of polysaccharide, flavonoids and alkaloids promoted the production of butyric acid but different secondary bile acids i.e. deoxycholic and ursodeoxycholic acids, acted in the intestine and liver, and intervened in more metabolic pathways, showing a synergistic effect on glycolipid metabolism. This study provided insights into the rational processing of lotus leaf for hypoglycaemic foods.