Regulation of Laminaria Polysaccharides with Different Degrees of Sulfation during the Growth of Calcium Oxalate Crystals and their Protective Effects on Renal Epithelial Cells

Abstract

The original Laminaria polysaccharide (LP0) was sulfated using the sulfur trioxide-pyridine method, and four sulfated Laminaria polysaccharides (SLPs) were obtained, namely, SLP1, SLP2, SLP3, and SLP4. The sulfated (–OSO3–) contents were 8.58%, 15.1%, 22.8%, and 31.3%, respectively. The structures of the polysaccharides were characterized using a Fourier transform infrared (FT-IR) spectrometer and nuclear magnetic resonance (NMR) techniques. SLPs showed better antioxidant activity than LP0, increased the concentration of soluble Ca2+ in the solution, reduced the amount of CaOx precipitation and degree of CaOx crystal aggregation, induced COD crystal formation, and protected HK-2 cells from damage caused by nanometer calcium oxalate crystals. These effects can inhibit the formation of CaOx kidney stones. The biological activity of the polysaccharides increased with the content of –OSO3−, that is, the biological activities of the polysaccharides had the following order: LP0 < SLP1 < SLP2 < SLP3 < SLP4. These results reveal that SLPs with high –OSO3− contents are potential drugs for effectively inhibiting the formation of CaOx stones.

Different Degrees of Sulfated Laminaria Polysaccharides Recovered Damaged HK-2 Cells and Inhibited Adhesion of Nano-COM and Nano-COD Crystals

“…The polysaccharides with sulfate contents of 0.73% (LP0), 15.1% (SLP1), 22.8% (SLP2), and 31.3% (SLP3) were obtained according to reference [ 23 ], and the sulfation reaction equation of LP0 was shown in Figure 1 . DMEM/F-12 culture medium and fetal bovine serum were purchased from Gibco (USA).…”

“…In our early work, we have sulfated the original laminaria polysaccharide (LP0, with sulfate contents of 0.73%), and three sulfated polysaccharides with –OSO 3 – content of 15.1% (SLP1), 22.8% (SLP2), and 31.3% (SLP3) were obtained [ 23 ]. The antioxidant activity of these SLPs and their ability to regulate CaOx crystal growth were investigated.…”

Synergistic inhibition of calcium oxalate crystal formation and synergistic protection of HK-2 cells from crystal damage by sulfatedLaminarinpolysaccharide and potassium citrate

“…DLP was sulfated by the sulfur trioxide–pyridine method according to the previously described method. 36 500 mg of DLP was weighed in a 250 mL conical flask, and 30 mL of dimethyl sulfoxide was added to it, and stirred at room temperature until the polysaccharide was completely dissolved. 5 g of sulfur trioxide–pyridine (completely dissolved in 5 mL of formamide) solution was added and reacted at 60 °C for 3 h. After cooling to room temperature, the solution was adjusted to pH 7.0 with 2 mol L −1 NaOH solution, and then transferred to a 500 Da dialysis bag for dialysis for 72 h. After that, it was concentrated under reduced pressure at 50 °C, precipitated with alcohol, stood overnight, and centrifuged and dried to obtain the sulfated Laminarin polysaccharide (SDLP).…”

Cell Protection and Crystal Endocytosis Inhibition by Sulfated Laminaria Polysaccharides Against Nano-COM-Induced Oxidative Damage in Renal Epithelial Cells

“…The extraction and sulfation of SLPs were performed with reference to our previous work. 26 The SLPs were extracted by the hot water extraction method, and the sulfur trioxide–pyridine method was used for sulfation.…”

“…Their sulfated (−OSO 3 – ) contents were 15, 23, and 31%, respectively. The sulfonation modification of LP0 enhances its crystallization regulation effect on CaOx crystals and inhibits the formation of COM crystals, the crystal form with high risk for kidney stone formation . The current study aims to study the protective effects of SLPs with different degrees of sulfonation on HK-2 cells and the inhibition of endocytosis of nano-COM crystals to determine the relationship between the content of sulfonic acid groups and the biological activity of polysaccharides, providing clarification for further development of drugs that can prevent and treat kidney stones.…”