Cui Yanlong, Wang Ruiling, Cao Siyue, Ismael Mohamedelfatieh, Wang Xin, Lü Xin
Lab of Bioresources, College of Food Science and Engineering, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi Province 712100, China; Shaanxi Engineering Research Centre of Dairy Products Quality, Safety and Health, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi Province 712100, China.
Lab of Bioresources, College of Food Science and Engineering, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi Province 712100, China.
Food Chem. 2023 Aug 1;416:135781. doi: 10.1016/j.foodchem.2023.135781. Epub 2023 Feb 24.
This research elucidated the structural characteristics and antioxidant activity of a galacturonic acid-rich polysaccharide (PPP-2) isolated from Diospyros kaki peel. PPP-2 was extracted by subcritical water and subsequently purified by DEAE-Sepharose FF column. PPP-2 (12.28 kDa) mainly contained galacturonic acid, arabinose, and galactose with the molar ratios of 87.15: 5.86: 4.31. The structural characteristics of PPP-2 were revealed through FT-IR, UV, XRD, AFM, SEM, Congo red, methylation, GC/MS assay and NMR spectrum. PPP-2 owned the triple helical structure and degradation temperature of 251.09 ℃. The backbone of PPP-2 was formed by →4)-α-d-GalpA-6-OMe-(1→ and →4)-α-d-GalpA-(1→ with the side chains of →5)-α-l-Araf-(1→, →3)-α-l-Araf-(1→, →3,6)-β-d-Galp-(1→ and α-l-Araf-(1→. Moreover, the inhibitory concentration (IC) of PPP-2 to ABTS•+, DPPH•, superoxide radical and hydroxyl radical were 1.96, 0.91, 3.63, and 4.08 mg/mL, respectively. Our results suggested that PPP-2 might be a novel candidate of natural antioxidant in pharmaceuticals or functional food.
本研究阐明了从柿皮中分离得到的富含半乳糖醛酸的多糖（PPP-2）的结构特征和抗氧化活性。PPP-2通过亚临界水提取，随后用DEAE-琼脂糖FF柱进行纯化。PPP-2（12.28 kDa）主要含有半乳糖醛酸、阿拉伯糖和半乳糖，摩尔比为87.15:5.86:4.31。通过傅里叶变换红外光谱（FT-IR）、紫外光谱（UV）、X射线衍射（XRD）、原子力显微镜（AFM）、扫描电子显微镜（SEM）、刚果红、甲基化、气相色谱/质谱联用（GC/MS）分析和核磁共振谱（NMR）揭示了PPP-2的结构特征。PPP-2具有三螺旋结构，降解温度为251.09℃。PPP-2的主链由→4)-α-d-半乳糖醛酸-6-甲酯-(1→和→4)-α-d-半乳糖醛酸-(1→组成，侧链为→5)-α-l-阿拉伯糖-(1→、→3)-α-l-阿拉伯糖-(1→、→3,6)-β-d-半乳糖-(1→和α-l-阿拉伯糖-(1→。此外，PPP-2对ABTS•+、DPPH•、超氧阴离子自由基和羟基自由基的抑制浓度（IC）分别为1.96、0.91、3.63和4.08 mg/mL。我们的结果表明，PPP-2可能是药物或功能性食品中天然抗氧化剂的新候选物。
