Lead is one of the most common heavy metal pollutants in the environment. Prolonged exposure to lead will induce oxidative stress, inflammation, and apoptosis in the kidneys, which in turn causes kidney injury. Lycium barbarum polysaccharide (LBP) is well known for its numerous pharmacological properties. This study aims to explore the efficacy and mechanism of LBP against lead-induced kidney damage in mice. Symptoms of renal injury were induced in mice by using 25 mg/kg lead acetate (PbAc₂), and different doses of LBP (200, 400, and 600 mg/kg BW) were orally administrated to PbAc₂-treated mice for five weeks. The results of the pharmacodynamics experiment showed that the renal pathological damages, serum creatinine (Cre), blood urea nitrogen (BUN), and kidney index of PbAc₂-treated mice could be significantly alleviated by treatment with LBP. Further, LBP treatment significantly increased the weight and feed intake of PbAc₂-treated mice. The dose effect results indicated that a medium dose of LBP was superior to high and low doses. The results of mechanistic experiments showed that LBP could attenuate oxidative stress, inflammation, and apoptosis in the kidneys of mice with lead toxicity by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway.

Background/Objectives: Mori fructus polysaccharides are key bioactive components with diverse activities, but structural characterization of homogeneous fractions remains limited, hindering insights into structure–activity relationships. This study addresses this gap by isolating and characterizing a homogeneous polysaccharide (MFP-III) from M. fructus. Methods: MFP-III, representing the final gel-filtration homogeneous fraction, was purified using defined procedures: DEAE-52 cellulose chromatography followed by Sephadex G-100 gel filtration. Purity and homogeneity were validated by high-performance liquid chromatography (HPLC). Structural characteristics were analyzed via HPLC, GC-MS, FTIR, and NMR spectroscopy. Meanwhile, hypoglycemic activity of MFP-III was evaluated. Results: MFP-III (94.2 ± 2.6%) has a molecular weight of approximately 6.83 kDa, primarily composed of rhamnose, arabinose, galactose, glucose, mannose, and galacturonic acid. Its backbone structure is presumed to be →2,4)-α-L-Rhap-(1 → 4)-α-D-GalpA-(1→, with branching units potentially attached to O-4. MFP-III demonstrated significant inhibitory activity against α-glucosidase (IC₅₀ = 1.56 mg/mL) and α-amylase (IC₅₀ = 2.07 mg/mL), stronger than acarbose at equivalent concentrations. Conclusions: The findings provide preliminary insights into the hypoglycemic structure–activity relationship of MFP-III, providing data support for the development of blood glucose-lowering natural inhibitors, and offering a theoretical foundation for advancing the application of polysaccharides from other sources.