Tartary buckwheat ( (L.) Gaertn) leaf has abundant rhamnogalacturonan-I enriched pectic polysaccharides, which exert various health-promoting effects. Nevertheless, the potential relationship between the chemical structure and the biological function of pectic polysaccharides from Tartary buckwheat leaves (TBP) remains unclear. Therefore, to bridge the gap between the chemical structure and the biological function of TBP, the impacts of ultrasound-assisted Fenton degradation (UFD) and mild alkaline de-esterification (MAD) on structural properties and biological effects of TBP were systematically studied. Compared with the native TBP (molecular mass, 9.537 × 10 Da), the molecular masses of degraded TBPs (TBP-MMW, 4.811 × 10 Da; TBP-LMW, 2.101 × 10 Da) were significantly reduced by the UFD modification, while their primary chemical structures were overall stable. Besides, compared with the native TBP (esterification degree, 22.73 %), the esterification degrees of de-esterified TBPs (TBP-MDE, 14.27 %; TBP-LDE, 6.59 %) were notably reduced by the MAD modification, while their primary chemical structures were also overall stable. Furthermore, the results revealed that both UFD and MAD modifications could significantly improve the antioxidant, antiglycation, and immunostimulatory effects of TBP. Indeed, TBP’s biological effects were negatively correlated to its molecular mass and esterification degree, while positively linked to its free uronic acids. The findings demonstrate that both UFD and MAD modifications are promising techniques for the structural modification of TBP, which can remarkedly promote its biological effects. Besides, the present results are conducive to better understanding TBP’s structure-bioactivity relationship.

中文翻译：

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超声辅助芬顿降解和碱脱酯对苦荞叶果胶多糖结构特性和生物效应的影响


苦荞 ((L.) Gaertn) 叶含有丰富的鼠李糖半乳糖醛酸-I 果胶多糖，具有多种促进健康的作用。然而，苦荞叶果胶多糖（TBP）的化学结构和生物功能之间的潜在关系仍不清楚。因此，为了弥合TBP化学结构和生物功能之间的差距，系统研究了超声辅助芬顿降解（UFD）和轻度碱性脱酯化（MAD）对TBP结构性质和生物效应的影响。与天然TBP（分子量，9.537 × 10 Da）相比，UFD修饰后，降解的TBP（TBP-MMW，4.811 × 10 Da；TBP-LMW，2.101 × 10 Da）的分子量显着降低，而其主要化学结构总体稳定。此外，与天然TBP（酯化度22.73%）相比，MAD改性后脱酯化TBP（TBP-MDE，14.27%；TBP-LDE，6.59%）的酯化度显着降低，而其主要化学成分则显着降低。结构也总体稳定。此外，结果表明UFD和MAD修饰均可显着提高TBP的抗氧化、抗糖化和免疫刺激作用。事实上，TBP的生物效应与其分子量和酯化度呈负相关，而与其游离糖醛酸呈正相关。研究结果表明，UFD和MAD修饰都是TBP结构修饰的有前途的技术，可以显着促进其生物学效应。此外，本研究结果有利于更好地理解TBP的结构-生物活性关系。