Moringa oleifera leaves (MOL) are a new food resource, rich in functional factors. MOL polysaccharides are important active macromolecules within MOL. However, there are problems, such as low extraction rates and lack of evidence for functional activity. Therefore, in this experiment, single-factor experiments were carried out using MOL powder as the raw material, and the Plackett–Burman test was used to screen the significantly influential test factors. The extraction process of MOL polysaccharide was optimized by response surface methodology. The insulin resistance alleviating activity of MOLP polysaccharides was initially explored. The results showed that the extraction of Moringa oleifera leaves crude polysaccharides (MOLP) by ultrasonic assisted cellulase enzymatic digestion was (17.03 ± 1.03)%, and the obtained MOLP was a crude polysaccharide with an average molecular weight (Mw) of 279.48 kDa, consisting of fucose, rhamnose, arabinose, galactose, glucose, xylose, mannose, galacturonic acid, and glucuronic acid. MOLP had an IC50 value of 8.02 mg/mL for α-glucosidase and scavenging activity against free radicals such as ABTS, DPPH, hydroxyl radicals, and superoxide anion with an IC50 value of 0.21 mg/mL 0.31 mg/mL 0.97 mg/mL 0.49 mg/mL. At the same time, MOLP significantly enhanced the glucose consumption, glycogen synthesis, CAT, SOD, GSH-Px activity, and reduced the MDA and ROS content in high glucose-induced insulin-resistant HepG2 (IR-HepG2) cells. This experiment improved the extraction rate of MOLP and demonstrated that MOLP has antioxidant activity and α-glucosidase inhibitory activity, which can alleviate the insulin resistance of high glucose-induced HepG2 cells. It provides partial data support for the possible hypoglycemic effect of MOLP by alleviating oxidative stress, and also provides new ideas for the in-depth study of basic research and industrial application of MOLP.

This study optimized the extraction process of crude polysaccharides from Panax notoginseng leaves (PNLP) using the ultrasonic-assisted dual-enzyme method through a single-factor combined with response surface experiment. The crude polysaccharides were subsequently purified and isolated with DEAE-Cellulose 52, followed by structural analysis, evaluation of antioxidant activity, and examination of digestive enzyme inhibition. The hypoglycemic effects of the purified components were further clarified. The results indicated that the optimized crude polysaccharide had an extraction yield of 17.13 ± 0.29%. The purified fraction PNLP-3 (eluted with 0.3 M NaCl) was obtained through DEAE-Cellulose 52 chromatography, exhibiting a total sugar content of 81.2% and a molecular weight of 16.57 kDa. PNLP is primarily composed of arabinose, galactose, and galacturonic acid, with molar percentages of 20.24%, 33.54%, and 24.27%, respectively. PNLP-3 is mainly composed of arabinose and galactose, with molar percentages of 29.97% and 49.35%, respectively. In this study of hypoglycemic activity, the IC₅₀ values of PNLP-3 for α-glucosidase and α-amylase inhibition were 1.045 mg/mL and 9.53 mg/mL, respectively. Molecular docking results confirmed that PNLP-3 exhibits better inhibitory activity against α-glucosidase. Furthermore, PNLP-3 alleviated hyperglycemia in insulin-resistant HepG2 cells by enhancing glucose consumption and glycogen synthesis. The antioxidant activity of PNLP-3 exhibited a positive correlation with its concentration, potentially contributing to its hypoglycemic effects by reducing oxidative stress. These findings underscore the therapeutic potential of Panax notoginseng leaf polysaccharides in managing type 2 diabetes and offer new perspectives on the use of natural polysaccharides for regulating blood glucose.

Finding stable and bioavailable calcium supplements is crucial for addressing calcium deficiency. In this study, glycated peptide–calcium chelates (WMPHs–COS–Ca) were prepared from walnut meal protein hydrolysates (WMPHs) and chitosan oligosaccharides (COSs) through the Maillard reaction, and the structural properties and stability of the WMPHs–COS–Ca were characterized. The results showed that WMPHs and COSs exhibited high binding affinities, with a glycation degree of 64.82%. After glycation, Asp, Lys, and Arg decreased by 2.07%, 0.46%, and 1.06%, respectively, which indicated that these three amino acids are involved in the Maillard reaction. In addition, compared with the WMPHs, the emulsifying ability and emulsion stability of the WMPHs–COS increased by 10.16 mg²/g and 52.73 min, respectively, suggesting that WMPHs–COS have better processing characteristics. After chelation with calcium ions, the calcium chelation rate of peptides with molecular weights less than 1 kDa was the highest (64.88%), and the optimized preparation conditions were 5:1 w/w for WMPH–COS/CaCl₂s, with a temperature of 50 °C, a chelation time of 50 min, and a pH of 7.0. Scanning electron microscopy showed that the “bridging role” of WMPHs-COS changed to a loose structure. UV–vis spectroscopy and Fourier transform infrared spectrometry results indicated that the amino nitrogen atoms, carboxyl oxygen atoms, and carbon oxygen atoms in WMPHs-COS chelated with calcium ions, forming WMPHs-COS-Ca. Moreover, WMPHs-COS-Ca was relatively stable at high temperatures and under acidic and alkaline environmental and digestion conditions in the gastrointestinal tract, indicating that WMPHs–COS–Ca have a greater degree of bioavailability.