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百香果高酯果胶

来源：花匠小妙招时间：2025-06-13 20:07

摘要： 本研究旨在解析漆酶介导合成的百香果高酯果胶（passion fruit high-methoxy pectin，PFP）和对香豆酸（p-coumaric acid，CA）及阿魏酸（ferulic acid，FA）衍生物的分子特性、红外光谱特征、体外抗氧化活性以及免疫活性，并与百香果高酯果胶-抗坏血酸衍生物（PFP-laccase-vitamin C，PFP-L-VC）（没有酚氧化成醌类并键结的参考组）对照比较。所得百香果高酯果胶-阿魏酸衍生物（PFP-laccase-ferulic acid，PFP-L-FA）和百香果果胶-对香豆酸衍生物（PFP-laccase-p-coumaric acid，PFP-L-CA）的总酚含量显著高于PFP和PFP-L-VC（P＜0.05）。相较于PFP的重均分子质量mw（190.5 kDa），PFP-L-CA的mw大幅提高至256.5 kDa，PFP-L-FA无明显变化，而PFP-L-VC则降低。两种酚酸衍生物都具有显著较小的Mark-Houwink-Sakurada指数（α）、环动半径（radius of gyration，Rg）和非均向性构型参数（ρ），显示其构象为无规则线圈状、链段柔软致密的球体。百香果高酯果胶-酚酸衍生物傅里叶变换红外光谱显示1 625 cm－1（自由羧基）处的峰面积明显减小，1 739 cm－1（酯化羧基）处的峰面积明显增加，说明酚酸与果胶的羧基形成酯基。和PFP相比，PFP-酚酸衍生物具有更高的体外抗氧化活性（羟自由基清除力、超氧阴离子自由基清除力、Fe2＋螯合力和总还原力）以及免疫活性（巨噬细胞增殖率、NO生成量与中性红吞噬能力），可刺激小鼠巨噬细胞释放较多的NO并增强细胞中性红吞噬能力。PFP-L-CA在1,1-二苯基-2-三硝基苯肼自由基清除率方面更优于PFP-L-FA和PFP-L-VC，与酚酸结构有关。本研究发现酚酸可赋予PFP衍生物优良的体外抗氧化活性和免疫活性，可为酚酸改性果胶在食品胶体和膳食纤维领域中的应用提供参考。

关键词: 百香果；高酯果胶；酚酸；分子特性；抗氧化活性；免疫活性

Abstract: This study aims to investigate the molecular characteristics, spectral characteristics, and in vitro antioxidant and immunomodulatory activities of laccase-mediated passion fruit high-methoxyl pectin (PFP) derivatives with ferulic acid (FA) or p-coumaric acid (CA) in comparison with those of its derivative with ascorbic acid (PFP-L-VC) (without linkage with quinones formed from phenolic oxidation). The contents of total phenolic compounds (TPC) of the derivatives PFP-L-FA and PFP-L-CA were significantly higher than those of PFP and PFP-L-VC (P < 0.05). The weight-average molecular mass (mw) of PFP-L-CA increased to 256.5 kDa, while the mw of PFP-L-FA did not change obviously, and the mw of PFP-L-VC decreased compared with that of PFP (190.5 kDa). Both phenolic acid derivatives showed significantly smaller Mark-Houwink-Sakurada exponent (α), radius of gyration (Rg), and anisotropic conformation parameter (ρ), implying a random-coil, flexible, dense, spherical conformation. Fourier transform infrared spectra displayed that the peak area at 1 625 cm-1 (free carboxyl group) decreased and the peak area at 1 739 cm-1 (esterified carboxyl group) increased, suggesting the formation of ester linkages between PFP’s carboxyl groups and phenolic acids. Compared with PFP, both PFP-phenolic acid derivatives had significantly improved in vitro antioxidant activities (in scavenging hydroxyl and superoxide anion radical, chelating Fe2+ and reducing power) and immunological activities (macrophage proliferation rate, NO release and neutral red phagocytosis), which could stimulate NO release from mouse macrophages and neutral red phagocytosis by mouse macrophages. In terms of scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, PFP-L-CA was superior to PFP-L-FA and PFP-L-VC, which may be related to phenolic acid structure. This study has demonstrated that phenolic acids can endow PFP derivatives with improved in vitro antioxidant and immunomodulatory activities, which will provide a theoretical basis for the application of phenolic acid-conjugated pectin as food gums and dietary fibers.

Key words: passion fruit; high-methoxy pectin; phenolic acid; molecular characteristics; antioxidant activity; immunological activity

中图分类号:

TS201.2