College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China.
Food Funct. 2018 Jun 20;9(6):3408-3418. doi: 10.1039/c8fo00563j.
In the present study, small angle X-ray scattering (SAXS) is applied to investigate the interaction between caseinophosphopeptides (CPP), the major digested product of milk protein, and chitosan (CS) under simulated gastrointestinal (GI) pH conditions. The change in pH value from the gastric to small intestinal environment induces complexation between CPP and CS, which is mainly driven by electrostatic interactions. The fractal dimension (Df) value of the domains inside the CPP-CS complexes is greater than 3, indicating the formation of dense particles/aggregates at the nanoscale. The Df value generally increases with an increase in the CS/CPP mass ratio. As a representative of polyphenols, (-)-epigallocatechin gallate (EGCG) associates with CS and CPP, forming nanocomplexes with a spherical shape and average particle size of around 208 nm. The formed CS-EGCG-CPP nanocomplexes do not affect the antioxidant activity of EGCG in the in vitro assays. Moreover, in the cellular assay, the nanocomplexes protect the RAW264.7 cells against H2O2-induced oxidative injury. In addition, the nanocomplexes significantly inhibit the lipopolysaccharide (LPS)-induced production of nitric oxide (NO), TNF-α, IL-1β and IL-6. Furthermore, they inhibit the expression of iNOS, phosphorylation and degradation of IκB, as well as the translocation of NF-κB p65; this indicates that the mechanism for their anti-inflammatory activity is via the mediation of the NF-κB signaling pathway.
在本研究中，应用小角 X 射线散射（SAXS）研究了在模拟胃肠道（GI）pH 条件下，牛奶蛋白主要消化产物酪蛋白磷酸肽（CPP）与壳聚糖（CS）之间的相互作用。从胃到小肠环境的 pH 值变化诱导 CPP 与 CS 之间的复合，这主要是由静电相互作用驱动的。CPP-CS 复合物内部区域的分形维数（Df）值大于 3，表明在纳米尺度上形成了密集的粒子/聚集体。Df 值通常随着 CS/CPP 质量比的增加而增加。作为多酚的代表，（-）-表没食子儿茶素没食子酸酯（EGCG）与 CS 和 CPP 结合，形成具有球形和平均粒径约为 208nm 的纳米复合物。形成的 CS-EGCG-CPP 纳米复合物不会影响 EGCG 在体外测定中的抗氧化活性。此外，在细胞测定中，纳米复合物可保护 RAW264.7 细胞免受 H2O2 诱导的氧化损伤。此外，纳米复合物还显著抑制脂多糖（LPS）诱导的一氧化氮（NO）、TNF-α、IL-1β 和 IL-6 的产生。此外，它们还抑制 iNOS 的表达、IκB 的磷酸化和降解以及 NF-κB p65 的易位；这表明其抗炎活性的机制是通过 NF-κB 信号通路的介导。
