桑叶黄酮提取物制备及其体外抗氧化作用研究

Study on the preparation of flavonoids extracted from mulberry leaves and its anti-oxidative activity in vitro

在单因素实验基础上,选取乙醇浓度、液料比、超声时间作为实验的三个因素,采用响应面分析法优化超声辅助乙醇法提取桑叶黄酮的工艺。以芦丁为标准品,采用硝酸铝-亚硝酸钠法测定黄酮含量。得超声辅助乙醇法最优工艺条件为:乙醇浓度51%,液料比25∶1,超声时间36min,黄酮得率为3.79%。以乙醇为洗脱液,采用AB-8大孔树脂对黄酮提取物进行吸附纯化,纯化后桑叶黄酮的纯度为52.34%。采用HPLC法对桑叶黄酮提取物进行组分分析,主要成分如下:绿原酸86.50mg/g,异槲皮苷60.94mg/g,紫云英苷35.12mg/g,芦丁23.75mg/g,槲皮素14.87mg/g。桑叶黄酮纯化后具有较强的体外抗氧化能力,其还原能力、清除DPPH·自由基(IC50=0.0363mg/mL)及·OH自由基(IC50=0.7063mg/mL)的能力分别是纯化前的2.21倍、6.24倍及2.59倍,且接近维生素C对照。

Based on the single factor experiment,ethanol concentration,liquid-to-material ratio and ultrasonic time were selected as experimental factors. Response surface methodology was used to optimize the process of flavonoids extraction from mulberry leaves by ultrasonic assisted ethanol extraction method. The flavonoids contents were determined by aluminum nitrate-sodium nitrite method. The optimum conditions of ultrasonic assisted ethanol extraction method were as follows :Ethanol concentration 51%,liquid-to-material ratio 25∶1,ultrasonic time 36 min. The flavonoids yield was 3.79% under the above extraction conditions. The flavonoids extract was then purified by AB-8 macroporous resin eluted by ethanol,and purity was 52.34%. HPLC method was used to analyze the components of flavonoids. The main components were as follows :Chlorogenic acid 86.50 mg/g,isoquercitrin 60.94 mg/g,astragalin 35.12 mg/g,rutin 23.75 mg/g,quercetin 14.87 mg/g. The purified mulberry leave flavonoids had stronger antioxidant capacity in vitro,and its reducing capacity,ability to scavenge DPPH · free radicals(IC50=0.0363 mg/mL)and · OH radicals(IC50=0.7063 mg/mL)were 2.21 times,6.24 times and 2.59 times,of the unpurified flavonoids,respectively. The results were close to that of vitamin C control.