Key Laboratory for Natural Active Pharmaceutical Constituents Research in Universities of Shandong Province, School of Pharmaceutical Sciences, Shandong Analysis and Test Center, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250014, China.
Nutrients. 2024 Oct 11;16(20):3446. doi: 10.3390/nu16203446.
Background: Accumulating research suggests that metabolites produced by gut microbiota are essential for maintaining a balanced gut and immune system. Indole-3-acetic acid (IAA), one of tryptophan metabolites from gut microbiota, is critical for gut health through mechanisms such as activating aryl hydrocarbon receptor. Delivery of IAA to colon is beneficial for treatment of gastrointestinal diseases, and one promising strategy is IAA esterified starch, which is digested by gut microbes in colon and releases loaded IAA. Amylose content is a key structural characteristic that controls the physicochemical properties and digestibility of starch.
In the current study, IAA was esterified with three typical starches with distinct amylose content to obtain indolyl acetylated waxy maize starch (WMSIAA), indolyl acetylated normal maize starch (NMSIAA), and indolyl acetylated high-amylose maize starch (HAMSIAA). The study comparatively analyzed their respective physicochemical properties, how they behave under in vitro digestion conditions, their ability to deliver IAA directly to the colon, and their effects on the properties of the gut microbiota.
The new characteristic peak of H NMR at 10.83 ppm, as well as the new characteristic peak of FTIR spectra at 1729 cm, represented the successful esterification of IAA on starch backbone. The following in vitro digestion study further revealed that treatment with indolyl acetylation significantly elevated the resistant starch content in the starch samples. In vivo experimental results demonstrated that WMSIAA exhibited the most significant increase in IAA levels in the stomach, whereas HAMSIAA and NMSIAA demonstrated the most remarkable increases in IAA levels in the small intestine and colon, respectively. The elevated IAA levels in the colon are conducive to promoting the growth of beneficial intestinal bacteria and significantly alleviating DSS-induced colitis.
This research presents innovative insights and options for the advancement of colon-specific drug delivery systems aimed at preventing and curing gastrointestinal disorders.
背景：越来越多的研究表明，肠道微生物产生的代谢物对于维持肠道和免疫系统的平衡至关重要。吲哚-3-乙酸（IAA）是肠道微生物产生的色氨酸代谢物之一，通过激活芳香烃受体等机制对肠道健康至关重要。将 IAA 递送到结肠有益于治疗胃肠道疾病，一种有前途的策略是 IAA 酯化淀粉，它在结肠中被肠道微生物消化，并释放负载的 IAA。直链淀粉含量是控制淀粉理化性质和消化性的关键结构特征。
在本研究中，将 IAA 与三种具有不同直链淀粉含量的典型淀粉进行酯化，得到吲哚基乙酰化蜡质玉米淀粉（WMSIAA）、吲哚基乙酰化普通玉米淀粉（NMSIAA）和吲哚基乙酰化高直链淀粉玉米淀粉（HAMSIAA）。本研究比较分析了它们各自的理化性质、在体外消化条件下的行为、直接将 IAA 递送到结肠的能力以及对肠道微生物特性的影响。
10.83ppm 处的新特征峰 H NMR 以及 1729cm 处的新特征峰 FTIR 光谱代表了 IAA 在淀粉主链上成功酯化。进一步的体外消化研究表明，吲哚基乙酰化处理显著提高了淀粉样品中的抗性淀粉含量。体内实验结果表明，WMSIAA 在胃中表现出 IAA 水平的最大增加，而 HAMSIAA 和 NMSIAA 分别在小肠和结肠中表现出 IAA 水平的最大增加。结肠中 IAA 水平的升高有利于促进有益肠道细菌的生长，并显著缓解 DSS 诱导的结肠炎。
本研究为开发旨在预防和治疗胃肠道疾病的结肠特异性药物递送系统提供了新的思路和选择。
