Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan.
Food Funct. 2015 Jul;6(7):2283-92. doi: 10.1039/c4fo01015a.
Practical application of tannic acid is limited because it readily binds proteins to form insoluble aggregates. In this study, tannic acid was self-assembled with fish scale gelatin hydrolysates (FSGH) to form stable colloidal complex nanoparticles. The nanoparticles prepared from 4 mg ml(-1) tannic acid and 4 mg ml(-1) FSGH had a mean particle size of 260.8 ± 3.6 nm, and showed a positive zeta potential (20.4 ± 0.4 mV). The nanoparticles acted as effective nano-biochelators and free radical scavengers because they provided a large number of adsorption sites for interaction with heavy metal ions and scavenging free radicals. The maximum adsorption capacity for Cu(2+) ions was 123.5 mg g(-1) and EC50 of DPPH radical scavenging activity was 21.6 ± 1.2 μg ml(-1). Hydroxyl radical scavenging effects of the nanoparticles were investigated by electron spin resonance spectroscopy. The copper-chelating capacity and free radical scavenging activity of the nanoparticles were associated with their capacity to inhibit Cu(2+) ion-induced barrier impairment and hyperpermeability of Caco-2 intestinal epithelial tight junction (TJ). However, α-amylase inhibitory activity of the nanoparticles was significantly lower than that of free tannic acid. The results suggest that the nanoparticles can ameliorate Cu(2+) ion induced intestinal epithelial TJ dysfunction without severely inhibiting the activity of the digestive enzymes.
单宁酸由于容易与蛋白质结合形成不溶性聚集体，因此其实际应用受到限制。在本研究中，单宁酸与鱼鳞明胶水解物（FSGH）自组装形成稳定的胶体复合纳米颗粒。由 4mg/ml 单宁酸和 4mg/ml FSGH 制备的纳米颗粒的平均粒径为 260.8±3.6nm，表现出正的 zeta 电位（20.4±0.4mV）。纳米颗粒作为有效的纳米生物螯合剂和自由基清除剂，因为它们提供了大量的吸附位点，可与重金属离子相互作用并清除自由基。对 Cu(2+)离子的最大吸附容量为 123.5mg/g，DPPH 自由基清除活性的 EC50 为 21.6±1.2μg/ml。通过电子自旋共振光谱研究了纳米颗粒的羟基自由基清除作用。纳米颗粒的铜螯合能力和自由基清除活性与其抑制 Cu(2+)离子诱导的 Caco-2 肠上皮紧密连接（TJ）障碍和高通透性的能力有关。然而，纳米颗粒的α-淀粉酶抑制活性明显低于游离单宁酸。结果表明，纳米颗粒可改善 Cu(2+)离子诱导的肠道上皮 TJ 功能障碍，而不会严重抑制消化酶的活性。
