Saponins have been extensively used in the food and pharmaceutical industries because of their potent bioactive and pharmacological functions including hypolipidemic, anti-inflammatory, expectorant, antiulcer and androgenic properties. A lot of saponins-containing foods are recommended as nutritional supplements for diabetic patients. As a medicine and food homologous material, Corni Fructus (CF) contains various active ingredients and has the effect of treating diabetes. However, whether and how CF saponins attenuate diabetes is still largely unknown. Here, we isolated total saponins from CF (TSCF) using ultrasonic microwave-assisted extraction combined with response surface methodology. The extract was further purified by a nonpolar copolymer styrene type macroporous resin (HPD-300), with the yield of TSCF elevated to 13.96 mg/g compared to 10.87 mg/g obtained via unassisted extraction. When used to treat high-fat diet and streptozotocin-induced diabetic mice, TSCF significantly improved the glucose and lipid metabolisms of T2DM mice. Additionally, TSCF clearly ameliorated inflammation and oxidative stress as well as pancreas and liver damages in the diabetic mice. Mechanistically, TSCF potently regulated insulin receptor (INSR)-, glucose transporter 4 (GLUT4)-, phosphatidylinositol 3-kinase (PI3K)-, and protein kinase B (PKB/AKT)-associated signaling pathways. Thus, our data collectively demonstrated that TSCF could be a promising functional food ingredient for diabetes improvement.

Hypoglycemic and hypolipidemic activities and underlying mechanisms of total triterpenoid acids from Corni Fructus.

Accumulating evidence suggests that gut microbiota plays a crucial role in the development of metabolic diseases, especially type 2 diabetes mellitus (T2DM). The nutrient-rich resource Cornus Fructus (CF) showed curative effects on diabetes mellitus. However, the mechanism underlying its hyperglycemic activity remains obscure. Herein, the antidiabetic potential of four extracts from CF, including saponin (CTS), iridoid glycoside (CIG), tannin (CT), and alcohol extract (CCA) was evaluated in vivo. The results showed that all four extracts could increase the body weight, decrease the blood glucose levels, and elevate the glucose tolerance. Moreover, insulin sensitivity and lipid profile were significantly improved in fed mice. In the [Formula: see text]-diversity index of samples, compared to the DM group, the diversity and richness of gut microbiota in mice to a certain extent were reduced in both CF extracts and Metformin (PC). Among them, there was statistical significance in PC (ACE, [Formula: see text]) and CCA (ACE, [Formula: see text]; chao1: [Formula: see text]). Beta diversity showed the same trend as the UPGMA clustering trees, which revealed that CF extracts could improve intestinal homeostasis in T2DM mice. Also, CF extracts could elevate the production of short-chain fatty acids, as well as regulate the composition of gut microbiota. The key bacteria related to T2DM including Firmicutes, Bacteroides, Lactobacillus, and Clostridium were modulated by metformin and CF. Altogether, CF is a potential nutrient-rich candidate that can be used in functional foods for the treatment of T2DM, and the change of gut microbiota might be a novel mechanism underlying its hyperglycemic activity.

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