College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, PR China.
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, PR China.
Int J Biol Macromol. 2021 Mar 15;173:13-25. doi: 10.1016/j.ijbiomac.2021.01.119. Epub 2021 Jan 19.
In this study, cassava starch aldehyde was functionalized with catechin through acid catalyzed condensation reaction. The structural characterization, stability and antioxidant activity of starch aldehyde-catechin conjugates were investigated. Thin layer chromatography revealed the conjugates did not contain free catechin. UV-vis spectra of the conjugates exhibited an absorption band at 280 nm, attributing to the B-ring of catechin moiety. Fourier-transform infrared and proton nuclear magnetic resonance spectroscopy demonstrated the conjugation occurred between the H-6/H-8 of catechin A-ring and the aldehyde groups of starch aldehyde. X-ray diffraction pattern indicated that the conjugates had an amorphous structure. Scanning electron microscopy showed the conjugates were fragmentary slices with rough surfaces. Notably, the conjugates were more stable than catechin in phosphate buffered saline (pH 7.4). In addition, the conjugates could not be digested in simulated saliva, gastric and small intestinal juices. The reducing power and free radical scavenging activity of starch aldehyde were remarkably elevated by conjugating with catechin. Meanwhile, the conjugates were non-cytotoxic to RAW264.7 mouse macrophage cells and possessed higher resistant starch contents than starch. Our results suggest starch aldehyde-catechin conjugates can be used as antioxidants in food industry.
本研究通过酸催化缩合反应，使木薯淀粉醛基与儿茶素发生功能化反应。研究了淀粉醛基-儿茶素缀合物的结构特征、稳定性和抗氧化活性。薄层层析表明缀合物中不含游离儿茶素。缀合物的紫外可见光谱在 280nm 处有一吸收带，归因于儿茶素部分的 B 环。傅里叶变换红外和质子核磁共振波谱表明，缀合反应发生在儿茶素 A 环的 H-6/H-8 与淀粉醛基之间。X 射线衍射图谱表明，缀合物具有无定形结构。扫描电子显微镜显示，缀合物是具有粗糙表面的碎片状薄片。值得注意的是，与儿茶素相比，缀合物在磷酸盐缓冲盐水（pH 7.4）中更稳定。此外，在模拟唾液、胃和小肠液中，缀合物不能被消化。通过与儿茶素缀合，木薯淀粉醛的还原能力和自由基清除活性显著提高。同时，与淀粉相比，缀合物对 RAW264.7 小鼠巨噬细胞无细胞毒性，且具有更高的抗性淀粉含量。我们的研究结果表明，淀粉醛基-儿茶素缀合物可用作食品工业中的抗氧化剂。
