半乳凝集素-3（Galectin-3，Gal-3）是肿瘤治疗的新靶标，通过与特定改性果胶片段特异性结合而产生抗肿瘤作用。该研究通过紫外光催化过氧化氢氧化法协同酸、碱对柑橘果胶进行定向降解改性，得到8种果胶降解产物，分别测定降解产物的分子量、甲基化程度和乙酰化程度等结构参数。再根据活性果胶片段与半乳凝集素-3特异性结合的原理，采用活性引导分离的思路，通过红细胞凝集实验和柱层析分离筛选出果胶活性片段UHP 4-5-0.3，其最小抑制浓度为0.016 mg/mL。CCK-8细胞抗增殖活性实验表明，UHP 4-5-0.3对三种Gal-3高表达肿瘤细胞人肝癌细胞HepG2、人乳腺癌细胞MCF-7、人宫颈癌细胞HeLa的增殖抑制率分别达到72.8%、90.0%、85.7%。通过FT-IR、1H NMR和HSQC的谱图分析确定了果胶活性片段的结构是由高度分支的鼠李半乳糖醛酸-I以及线性聚半乳糖醛酸共同组成。该研究发现为从果胶高效获取新型食品功能因子提供了新的思路。

Galectin-3 (Gal-3) is a new target for tumor therapy, which exerts anti-tumor effects through the specific binding with the modified pectin fragments. In this study, the pectin from citrus peel was directionally degraded by ultraviolet light catalytic hydrogen peroxide oxidation in synergy with acid or alkaline, resulting in eight degraded pectin products. The structural parameters of the degraded products, including molecular weight, degree of methylation and degree of acetylation were determined. The activity-guided separation was accomplished based on the specific binding between the active pectin fragments and Gal-3. The active pectin fragment UHP 4-5-0.3, having the minimum inhibition concentration (MIC) of 0.016 mg/mL, was screened out through the hemagglutination assay and column chromatography separation. The CCK-8 anti-proliferation activity assay revealed that the proliferation inhibition rates of UHP 4-5-0.3 against the three types of Gal-3 highly-expressed tumor cells, HepG2, MCF-7 and HeLa, reached 72.8 %, 90.0 %, and 85.7 %, respectively. The structure of the active pectin fragment was determined to be composed of a highly branched rhamnogalacturonan I and a linear homogalacturonan by FT-IR, 1H NMR and HSQC analyses. The findings of this study provide a new idea for efficiently obtaining a novel food functional ingredient from pectin.

国家重点研发计划政府间国际科技合作重点专项（2021YFE0190300）