桑叶多糖的提取与降血糖功能研究

Extraction of Polysaccharide from Mulberry Leaves and Study on Its Hypoglycemic Function

目的:研究不同季节"湖桑"桑叶中总多糖含量和提取方法及其降血糖功能。方法:采用苯酚-硫酸法测定新鲜桑叶总多糖含量,采用正交设计试验确定桑叶多糖的最佳提取工艺。以小鼠为试验对象,将其处理为阳性对照组、桑叶多糖组、正常空白对照组(前两组都注射1%四氧嘧啶,第3组不注射),连续30 d测定空腹血糖值,比较各组动物血糖值及血糖下降率。结果:浙江绍兴地区"湖桑"桑叶多糖含量在五月份为6.72 mg/g,七月份为5.73 mg/g,八月份为7.63 mg/g,九月份为8.68 mg/g,十月份为8.59 mg/g。提取的桑叶总多糖含量最高为20.71 mg/g,此时提取条件是:提取温度40℃,固液比1∶40,提取时间40 min,提取次数4次。桑叶多糖组相对于正常空白对照组血糖下降率为56.82%。结论:浙江绍兴地区"湖桑"桑叶多糖含量在九月份最高;提取温度为40℃,固液比为1∶40,提取时间为40 min,提取次数4次为最佳提取条件;口服桑叶多糖对四氧嘧啶(Alloxan,ALX)诱导的糖尿病小鼠具有显著的降血糖的功能。

Objective： To study the total content of polysaccharides and their extraction methods as well as their ef- fects in decreasing blood sugar in ＇Hu Sang＇ leaves of different seasons. Method： Phenol-sulfuric acid method was used to measure total concentration of polysaccharides in mulberry leaves and orthogonal experimental design was used to determine their optimal extraction conditions. Three groups of rats, positive control group, experimental group and normal blank group, were served as experimental subjects, the former two of which were injected with 1% tetraoxypyrimidine and the later one not. Fasting blood sugar level of every rat was measured for 30 days. Blood sugar content and its decreasing rate of each group of rats were compared. Results： The total content of polysaccharides of ＇Hu Sang＇ leaves in Shaoxing, Zhejiang was 6.72 mg/g in May, 5.73 mg/g in July, 7.63 mg/g in August, 8.68 mg/g in September and 8.59 mg/g in October. The maximal sugar content of the leaves was 20.71 mg/g when extracted in 40 ℃ for 40 min with sol- id-liquid ratio of 1：40 for 4 times. The blood sugar content of experimental group were decreased 56.82% compared by the control group. Conclusion： The maximal polysaccharides content of ＂Hu Sang＂ leaves was obtained in September with the extraction condition of 40 ℃ for 40 min with solid-liquid ratio of 1：40 for 4 times. It had remarkable effects on the decrease of blood sugar level of diabete rats induced by tetraoxypyrimidine （Alloxan, ALX） when the rats eat mulberry leaves.