紫花苜蓿多糖的制备及其对肠道菌群调节机制研究

Medicago sativa L.(alfalfa) is one of the most productive and widely distributed herbage in the world, which contains abundant nutritive and active ingredients. Meanwhile, alfalfa is known as the "King of grass" and "Universal plant". Previous studies found that alfalfa polysaccharides has many biological activities such as enhancing immunity, antitumor and antioxidation, which has important medicinal research and developing value. Alfalfa has been used directly as animal feed or as an extract form to improve the quality of animal products, thus failing to achieve efficient utilization. This study used alfalfa as raw material to investigate the effects of extraction methods on the physicochemical properties and fermentation characteristics of alfalfa polysaccharides. High-activity alfalfa polysaccharides were prepared and analyzed by modern separation and structure characterization techniques. The fermentation characteristics of alfalfa polysaccharides and human gut microbiota were studied by in vitro fermentation. The high-throughput sequencing and fluorescent labeling techniques were also used to explore the effects of alfalfa polysaccharides on regulation mechanism of human gut microbiota. Our results can not only increase the additional value of alfalfa, but also provide a new direction for the deep processing of herbage resources.

紫花苜蓿是世界上产量大、分布广的牧草之一，含有丰富的营养成分和活性成分，被誉为“牧草之王”和“万能植物”。研究发现，苜蓿多糖具有增强免疫、抗肿瘤、抗氧化等多种生物活性，有重要的药用研究和开发利用价值。以往紫花苜蓿被直接作为畜禽饲料使用或者以提取物形式添加到饲料中提高畜禽产品的品质，未能达到高值化利用的效果。本项目以紫花苜蓿为原料研究提取方法对苜蓿多糖理化性质及发酵特性的影响规律；借助现代分离、结构表征技术，制备和解析高活性的苜蓿多糖；采用体外发酵技术研究苜蓿多糖与人肠道菌群的发酵特性，结合高通量测序技术和荧光标记技术探明苜蓿多糖对人肠道菌群调节的作用机制。研究结果不仅可以提高紫花苜蓿的附加值，同时也能给牧草资源的深加工提供新方向。

紫花苜蓿是世界上产量大、分布广的牧草之一，含有丰富的营养成分和活性成分，被誉为“牧草之王”和“万能植物”。苜蓿多糖具有增强免疫、抗肿瘤、抗氧化等多种生物活性，有重要的药用研究和开发利用价值。以往紫花苜蓿被直接作为畜禽饲料使用或者以提取物形式添加到饲料中提高畜禽产品的品质，未能达到高值化利用的效果。课题以紫花苜蓿为原料研究了五种提取方法对苜蓿多糖理化性质和肠道菌群调节作用的影响。不同方法提取的苜蓿多糖在调节肠道菌群作用方面有一定的差异性，经筛选发现，酶法、超声法、超声-酶法提取的苜蓿多糖可以较好的发挥调节肠道菌群的作用。以超声法提取的苜蓿多糖为原料研究其对免疫损伤小鼠免疫功能保护和肠道菌群调节的作用，在体内进一步验证了苜蓿多糖具有调节肠道菌群的功能，尤其是对乳杆菌的调节作用十分显著。采用柱色谱等方法对酶法和超声法提取的苜蓿粗多糖进行了分离纯化，获得了两种精制苜蓿多糖，并对其结构进行了表征研究。明确了苜蓿多糖对鼠李糖乳杆菌具有显著促生长作用。研究结果为今后苜蓿多糖作为调节肠道微生态产品的开发提供了理论基础，同时也为紫花苜蓿的深加工和高值化利用提供了新的研究方向。