低分子量硫酸软骨素体外酵解特征及其对肠道菌群的调节作用

In Vitro Fermentation Characteristics of Low-molecular-weight Chondroitin Sulfate and Its Regulatory Effects on Gut Microbiota

摘要:

硫酸软骨素（Chondroitin sulfate，CS）具有调节肠道微生物的作用，但不同分子量对其益生活性的影响鲜有报道。该研究比较了硫酸软骨素（80 ku）及其光催化降解产物（Low Molecular Weight Chondroitin Sulfate，LWCS，4 ku）体外酵解特征及其对肠道代谢物的影响。通过化学法、气相色谱质谱联用、高通量测序等方法测定了不同时间发酵液中pH值、CS和LWCS含量、还原糖含量、短链脂肪酸浓度以及肠道微生物的变化。结果显示，在发酵48 h内，CS、LWCS以及还原糖含量均显著降低（P<0.05），说明肠道微生物能够降解利用硫酸软骨素及其降解产物。且降解后的硫酸软骨素更显著地增加了拟杆菌门和副杆菌属等有益菌的丰度（P<0.05），更明显的抑制了潜在致病菌型埃希氏-志贺氏菌属（P<0.05）。此外，LWCS发酵能维持24 h的酸性环境，并产生更多的乙酸、丙酸和总短链脂肪酸（分别增加1.15、1.03和1.09倍）。以上结果表明，光催化降解后的硫酸软骨素具有更强的肠道益生作用，该研究为硫酸软骨素的开发应用提供了科学依据。

Abstract:

Chondroitin sulfate (CS) can regulate gut microbiota; however, the effects of different molecular weights on its probiotic activity remain unclear. The in vitro fermentation characteristics of CS (80 ku) and its photocatalytic degradation products (low-molecular-weight chondroitin sulfate, LWCS, 4 ku) were evaluated, and their effects on intestinal metabolites were compared. The pH values, CS and LWCS contents, reducing sugar content, short-chain fatty acid (SCFA) concentration, and the gut microbiota in fermentation solutions at different times were determined using chemical methods, gas chromatography-mass spectrometry, and high-throughput sequencing. The results show that the CS, LWCS, and reducing sugar contents decrease significantly during the 48 h fermentation (P<0.05), indicating that the gut microbiota broke down and utilized CS and its degradation products. Moreover, degraded chondroitin sulfate significantly increased the abundance of beneficial bacteria, including Bacteroides and Parabacteroides (P<0.05) while inhibiting potentially pathogenic bacteria, such as Escherichia-Shigella (P<0.05). Additionally, acetic acid, propionic acid, and total SCFAs produced by LWCS exhibited 1.15-, 1.03-, and 1.09-fold increases, respectively. LWCS fermentation can also maintain an acidic environment for 24 h. This study demonstrated that the photocatalytic degradation products of CS exhibited a stronger probiotic effect than CS, thus providing a scientific basis for further advancement and application of CS.