Microbiome Medicine Center, Department of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
School of Business Administration, Guangzhou Institute of Science and Technology, Guangzhou 510282, China.
Ultrason Sonochem. 2023 Dec;101:106652. doi: 10.1016/j.ultsonch.2023.106652. Epub 2023 Oct 17.
In this study, a high-molecular-weight Pueraria lobata polysaccharide (PLP) with a molecular weight of 273.54 kDa was degraded by ultrasound, and the ultrasonic degradation kinetics, structural characteristics and hepatoprotective activity of ultrasonic degraded PLP fractions (PLPs) were evaluated. The results showed that the ultrasonic treatment significantly reduced the Mw and particle size of PLP, and the kinetic equation of ultrasonic degradation of PLP followed to the midpoint fracture model (the fist-order model). The monosaccharide composition analysis, FT-IR, triple helix structure and XRD analysis all indicated that the ultrasound degradation did not destroy the primary structure of PLP, but the thermal stability of degraded fractions improved. Additionally, the scanning electron microscopy analysis demonstrated that the surface morphology of PLP was altered from smooth, flat, compact large flaky structure to a sparse rod-like structure with sparse crosslinking (PLP-7). The degraded PLP fractions (0.5 mg/mL) with lower Mw exhibited better antioxidant activities and protective effects against palmitic acid-induced hepatic lipotoxicity, which may be due to the increased exposure of active groups such as hydroxyl groups of PLP after ultrasound. Further investigation showed that PLPs not only increased Nrf2 phosphorylation and its nuclear translocation, thereby activating Nrf2/Keap1 signaling pathway, but also enhanced HO-1, NQO-1, γ-GCL gene expressions and promoted superoxide dismutase and catalase activities, which protected hepatocytes against PA-induced oxidative stress and lipotoxicity. Overall, our research might provide an in-depth insight into P. Lobata polysaccharide in ameliorating lipid metabolic disorders, and the results revealed that ultrasonic irradiation could be a promising degradation method to produce value-added polysaccharide for use in functional food.
在这项研究中，一种分子量为 273.54 kDa 的高分子量葛根多糖（PLP）通过超声降解，评估了超声降解 PLP 级分（PLPs）的超声降解动力学、结构特征和肝保护活性。结果表明，超声处理显著降低了 PLP 的 Mw 和粒径，PLP 超声降解的动力学方程符合中点断裂模型（一级模型）。单糖组成分析、FT-IR、三螺旋结构和 XRD 分析均表明，超声降解并未破坏 PLP 的一级结构，但降解级分的热稳定性提高。此外，扫描电子显微镜分析表明，PLP 的表面形态从光滑、平坦、致密的大片状结构变为稀疏的棒状结构，交联稀疏（PLP-7）。Mw 较低的降解 PLP 级分（0.5mg/mL）表现出更好的抗氧化活性和对棕榈酸诱导的肝脂肪毒性的保护作用，这可能是由于超声后 PLP 中羟基等活性基团的暴露增加所致。进一步的研究表明，PLPs 不仅增加了 Nrf2 的磷酸化及其核易位，从而激活了 Nrf2/Keap1 信号通路，还增强了 HO-1、NQO-1、γ-GCL 基因的表达，并促进了超氧化物歧化酶和过氧化氢酶的活性，从而保护肝细胞免受 PA 诱导的氧化应激和脂肪毒性。总的来说，我们的研究可能深入了解葛根多糖在改善脂质代谢紊乱方面的作用，研究结果表明，超声辐射可能是一种有前途的降解方法，可以生产出用于功能性食品的增值多糖。
