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A water-soluble polysaccharide (HPS3aS) with a molecular mass of 1.22 × 10(4) Da was isolated from Hedysarum polybotrys using anion-exchange and gel-permeation chromatography. HPS3aS exhibits a globular-shaped conformation in 0.1 M NaNO3 by size exclusion chromatography with multi-angle laser light scattering (SEC-MALLS). The investigation of the structural features of this heteropolysaccharide through a combination of chemical and instrumental analyses revealed that the backbone of HPS3aS is composed of α-D-(1 → 4)-linked glucopyranose residues, which occasionally branched at O-6. The branches are composed of (1 → 4)-linked galactopyranose residues and terminated with glucopyranose residues. HPS3aS possesses good in vitro antioxidant activity, as evaluated by scavenging assays with 1,1-diphenyl-2-picrylhydrazyl, hydroxyl, and superoxide radicals, which suggests that HPS3aS could be a potential antioxidant.

Objectives To explore the mechanism of calcium-sensing receptors (CaSRs) during the development of nephrolithiasis. Materials and methods Wistar rats were treated with ethylene glycol to induce calcium oxalate crystallization, and gadolinium chloride (GdCl 3 , an agonist of CaSR) and NPS 2390 (an antagonist of CaSR) were added. Oxidative stress (OS) and calcium oxalate crystals in the kidney were observed. CaSR expression and the expression of extracellular signal-regulated protein kinase (ERK), OPN, and KIM-1 were determined by western blotting. In addition, renal tubular epithelial cells were isolated from the kidney to observe phosphatidylserine (PS) ectropion using flow cytometric analysis. Various biochemical parameters were assessed in serum and urine at the end of the experiment. Results Calcium oxalate increased OS, crystal adhesion, PS ectropion, and the expression of CaSR and ERK, OPN, and KIM-1 in vivo . In addition, lower levels of urine citrate as well as increased serum creatinine and urea levels were observed after treatment with calcium oxalate ( p < .05). Compared with calcium oxalate treatment alone, the above deleterious changes were further significantly confirmed by GdCl 3 but were reversed by NPS-2390. However, urine calcium excretion was decreased after ethylene glycol treatment but was significantly reduced by NPS 2390 and increased by GdCl 3 ( p < .05). Conclusions The results suggest that CaSR might play significant roles in the induction of nephrolithiasis in rats by regulating reactive oxygen species (ROS) and PS ectropion and the composition of urine, OPN, KIM-1, and ERK expression.

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