羟基酪醇脂肪酸酯与肠道菌群互作效应及机制的构效关系研究

Lipophenols can be manufactured by linking of fatty acids with polyphenols through ester bonds. Compared to polyphenols themselves, their lipophilic derivatives have several advantages such as combining the health-related benefits of both fatty acid and polyphenol in a single lipophenolic molecule, and increasing the protective effects on lipidic food matrices from oxidation. Therefore, lipophenols have extensive application prospects as food antioxidants and novel source of ingredients for functional foods. Our previous studies indicated that lipophenols could be hydrolyzed by pancreatin and pancreatic lipase to free phenols in small intestine, and the latter (free polyphenols) could be transported across the intestinal mucosa. However, part of lipophenols could reach the large intestine and cecum after oral administration, and could be hydrolyzed by intestinal bacteria such as Pseudomonas aeruginosa to free polyphenols. However, the exact mechanisms of interactions between lipophenols and intestinal microflora are still unclear. In this project, the metabolic pathways and structure-activity relationship of hydroxytyrosol acyl esters under the effects of intestinal microflora will be revealed by using in vitro anaerobic fermentation accompanied by lipidomic analysis, and further the specific bacteria involved in the metabolic process as well as their metabolic mechanism will also be revealed. On the other hand, the regulatory action of hydroxytyrosol acyl esters on the intestinal microbiota will be evaluated by metagenome-based technologies accompanied by strain isolation and separation-purification of metabolites, and further the key metabolites involved in the above regulatory process and their mechanism will be revealed. On the whole, this project can demonstrate the mechanism of interaction between lipophenols and intestinal microflora, which would clarify the in vivo process of lipophenols and provide a theoretical basis for their utilization as novel sources of ingredients for functional foods.

酚酯是多酚和脂肪酸通过化学键键合而成。与多酚相比，酚酯可提升多酚对亲脂性食品基质的抗氧化作用，还可将多酚和脂肪酸的健康有益作用有机结合，在食品抗氧化领域和功能食品领域具有广阔的应用前景。课题组前期研究表明，酚酯虽可在小肠中被胰酶和胰脂肪酶水解，以游离多酚的形式跨越肠黏膜，但部分酚酯可到达盲肠和大肠，并在肠道细菌的水解作用下产生游离多酚。但是，酚酯与肠道菌群互作效应及机制尚不清晰。本项目拟通过脂质组学辅以肠道细菌体外厌氧发酵技术揭示羟基酪醇脂肪酸酯在肠道菌群作用下的代谢路径及构效关系，探明参与代谢的关键菌及其代谢机制；通过宏基因组学辅以菌种分离、代谢物分离纯化等技术，揭示羟基酪醇脂肪酸酯对肠道菌群调节作用的构效关系，明确起调节作用的关键结构并阐述其调节机制。本项目以酚酯与肠道菌群的相互作用为切入点，可进一步明确酚酯的体内过程，为其在功能食品领域的应用提供科学依据。

酚酯是多酚（或酚酸）和脂肪酸（或脂肪醇）反应生成的产物。近年来，由于其较强的亲脂性和抗氧化能力，已被允许用作食品类抗氧化剂。目前，国家食品药品监督管理局将没食子酸丙酯和茶多酚棕榈酸酯列为食品抗氧化剂，其中茶多酚棕榈酸酯最大使用量为600mg/kg，而没食子酸丙酯的最大添加量则为400mg/kg。此外，酚酯还具有抗氧化、抗炎等生物活性。然而，酚酯在机体内的消化、吸收和代谢以及与肠道菌群互作效应及机制尚不十分清晰。本项目研究发现口服酚酯可以在胃中稳定存在，在小肠中可以被胰脂肪酶和羧酸酯酶水解释放游离多酚和脂肪酸。酚酯、游离多酚和脂肪酸可以跨过小肠黏膜进入血液，而酚酯仍然可以在血浆中继续发生水解反应。与游离多酚相比，酚酯组的代谢和排泄速度更慢，体内作用时间也更长。此外，虽然酚酯会在小肠内发生水解反应，但仍有部分酚酯可以到达盲肠和大肠，具有修复肠道损伤的作用。盲肠和结肠中存在大量厌氧或兼性厌氧菌，约翰逊乳杆菌、罗伊氏乳杆菌和加塞利乳杆菌等乳酸杆菌均可以水解酚酯，释放游离多酚和脂肪酸。随着烷基链长度的增加，酚酯的水解速率先升高后降低。其中，4-6酯的水解速率最大。鉴于此，酚酯在肠道菌群作用下发生水解反应释放游离多酚和脂肪酸，与酚酯可发挥协同促进肠道菌群生长的能力。相关结果为拓宽羟基酪醇脂肪酸酯等酚酯在功能食品领域的应用提供了理论支撑。因此，羟基酪醇脂肪酸酯等酚酯既可以用作食用油脂的的新型抗氧化剂，又可以用作功能食品新型基料，社会效益显著。