College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China.
College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China.
Int J Biol Macromol. 2020 Jan 15;143:49-59. doi: 10.1016/j.ijbiomac.2019.12.037. Epub 2019 Dec 5.
In this study, gallic acid (GA) was grafted onto O-carboxymethyl chitosan (O-CMCS) by a free radical-mediated method. The synthesized GA grafted CMCS (GA-g-CMCS) was characterized by several instrumental methods and the antioxidant activity of the conjugate was evaluated by in vitro and cellular assays. Results showed the grafting ratio of GA-g-CMCS was 60.8 mg GAE/g. Thin layer chromatography and UV-vis, Fourier-transform infrared and proton nuclear magnetic resonance spectroscopic analyses all confirmed GA was successfully grafted onto O-CMCS. Meanwhile, covalent linkage formed between the amino group of O-CMCS and the carboxyl group of GA via amide bond. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and the reducing power of O-CMCS were remarkably improved by grafting with GA. Cellular assays showed GA-g-CMCS was non-toxic to RAW264.7 cells at 25-400 μg/mL. Moreover, GA-g-CMCS had a protective effect against hydrogen peroxide (HO)-induced oxidative damage in RAW264.7 cells. As compared with HO-treatment alone, the pretreatment of the cells with 100, 200 and 400 μg/mL of GA-g-CMCS significantly increased cell viability, reduced apoptosis and intracellular reactive oxygen species production, and improved membrane integrity and intracellular antioxidant enzyme (superoxide dismutase, catalase, glutathione peroxidase) activity. Our results suggested GA-g-CMCS could be developed as a novel antioxidant.
在这项研究中，通过自由基介导的方法将没食子酸（GA）接枝到 O-羧甲基壳聚糖（O-CMCS）上。合成的 GA 接枝 CMCS（GA-g-CMCS）通过多种仪器方法进行了表征，并通过体外和细胞测定评估了该缀合物的抗氧化活性。结果表明，GA-g-CMCS 的接枝率为 60.8 mg GAE/g。薄层层析和紫外-可见、傅里叶变换红外和质子核磁共振波谱分析均证实 GA 成功接枝到 O-CMCS 上。同时，O-CMCS 的氨基和 GA 的羧基之间通过酰胺键形成了共价键。GA 接枝大大提高了 O-CMCS 的 2,2-二苯基-1-苦基肼自由基清除活性和还原能力。细胞实验表明，GA-g-CMCS 在 25-400 μg/mL 时对 RAW264.7 细胞无毒。此外，GA-g-CMCS 对 RAW264.7 细胞中过氧化氢（HO）诱导的氧化损伤具有保护作用。与单独 HO 处理相比，用 100、200 和 400 μg/mL 的 GA-g-CMCS 预处理细胞可显著提高细胞活力，减少细胞凋亡和细胞内活性氧产生，并改善膜完整性和细胞内抗氧化酶（超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化物酶）活性。我们的研究结果表明，GA-g-CMCS 可开发为一种新型抗氧化剂。
