Qi Xiaodan, Yu Yang, Wang Xinyi, Xu Jialei, Wang Xiang, Feng Zhangkai, Zhou Yifa, Xiao Hongxing, Sun Lin
School of Life Sciences, Northeast Normal University, Changchun, China.
Department of Clinical Biochemistry, Qiqihar Medical University, Qiqihar, China.
Front Nutr. 2022 Sep 20;9:998462. doi: 10.3389/fnut.2022.998462. eCollection 2022.
Pectins are nutrient components of plants and are widely used in the food industry. In this study, one major pectin fraction (WLJP-A0.2b) with Mw of 40.6 kDa was purified from Thunb. The structural feature and antioxidant activity of it was investigated. Monosaccharide composition, Fourier transform infrared (FT-IR) spectra, enzymatic hydrolysis, and nuclear magnetic resonance (NMR) spectra analysis indicated that WLJP-A0.2b consisted of rhamnogalacturonan I (RG-I), rhamnogalacturonan II (RG-II), and homogalacturonan (HG) domains, with mass ratio of 0.4:1.0:2.1. The RG-I domain contained highly branched α-L-1,5-arabinan, β-D-1,4-galactan and type II arabinogalactan (AG-II) side chains. The HG domain was released in the form of un-esterified and partly methyl-esterified and/or acetyl-esterified oligogalacturonides with degree of polymerization 1-8 after degradation by endo-polygalacturonase. Radical scavenging assays indicated that WLJP-A0.2b exhibited antioxidant activity through the synergistic effects of different pectin domains. Oligogalacturonides, especially de-esterified oligogalacturonides, showed better antioxidant activities than RG-II and RG-I domains. Moreover, de-esterified oligogalacturonides remarkably reduced HO-induced reactive oxygen species production in HEK-293T cells. These results provide useful information for screening of natural antioxidants from Thunb. and application of pectin in functional food field.
果胶是植物的营养成分，在食品工业中广泛应用。本研究从[植物名称未给出]中纯化出一种分子量为40.6 kDa的主要果胶组分（WLJP - A0.2b），并对其结构特征和抗氧化活性进行了研究。单糖组成、傅里叶变换红外光谱（FT - IR）、酶解以及核磁共振（NMR）光谱分析表明，WLJP - A0.2b由鼠李半乳糖醛酸聚糖I（RG - I）、鼠李半乳糖醛酸聚糖II（RG - II）和同型半乳糖醛酸聚糖（HG）结构域组成，质量比为0.4:1.0:2.1。RG - I结构域包含高度分支的α - L - 1,5 - 阿拉伯聚糖、β - D - 1,4 - 半乳聚糖和II型阿拉伯半乳聚糖（AG - II）侧链。HG结构域在经内切多聚半乳糖醛酸酶降解后，以聚合度为1 - 8的未酯化、部分甲基酯化和/或乙酰酯化的低聚半乳糖醛酸形式释放。自由基清除试验表明，WLJP - A0.2b通过不同果胶结构域的协同作用表现出抗氧化活性。低聚半乳糖醛酸，尤其是去酯化的低聚半乳糖醛酸，表现出比RG - II和RG - I结构域更好的抗氧化活性。此外，去酯化的低聚半乳糖醛酸显著降低了HEK - 293T细胞中HO诱导的活性氧生成。这些结果为从[植物名称未给出]中筛选天然抗氧化剂以及果胶在功能性食品领域的应用提供了有用信息。
