桑叶总生物碱提取及其与牛血清蛋白结合能力研究OA

The total alkaloids were extracted from mulberry leaves by ultrasonic low-temperature extraction process.Based on single factor experiments,the extraction process was optimized by response surface method.The main structures of total alkaloids from mulberry leaves were identified and analyzed by liquid chromatography/mass spectrometry,and the binding ability of total alkaloids from mulberry leaves to bovine serum albumin(BSA)was studied through a series of spectra.The results showed that the optimal extraction process of total alkaloids from mulberry leaves was as follows:mulberry leaves of 3.0 g,solid-liquid ratio of 0.05 mol/L hydrochloric acid solution to mulberry leaves10∶1(mL∶g),ethanol volume fraction of 33%,ultrasonic power of 250 W,extraction temperature of 40℃,extraction time of 30 min,and two times of extraction.Under these conditions,the extraction amount of total alkaloids from mulberry leaves was 2.596±0.13 mg/g.According to the analysis by liquid chromatography/mass spectrometry(LC/MS),there were four main structures of total alkaloids from mulberry leaves,2-O-α-D-galactopyranosyl-deoxynojirimycin,1-deoxynojirimycin(1-DNJ),1,4-dideoxy-1,4-imino-D-arabinitol and fagomine.It could be seen from the fluorescence spectrum that the total alkaloids from mulberry leaves could bind to BSA with a binding constant of(9.79±0.23)×103 L/(mol·s).Circular dichroism analysis confirmed that total alkaloids from mulberry leaves could alter the secondary structure of BSA.