Detection, Extraction And Functional Activity Analysis Of The 1-deoxynojirimycin From Mulberry Leaves

1-deoxynojirimycin (DNJ) in Mulberry leaves has a variety of important physiological function, such as a-glucosidase and glucoamylase inhibition, anti-virus, body weight loss and insulin sensitivity increase. Firstly, a sensitive method of RP-HPLC-UV was established to detect DNJ contents in mulberry leaves. Using the method, we not only measured DNJ contents in 132 varieties of mulberry, but also studied various purification process of DNJ from mulberry leaves. Finally, hypoglycemic activity of DNJ was estimated in diabetic mice.In order to determine DNJ contents in mulberry leaves, a RP-HPLC-UV method with 9-fluorenylmethyl chloroformate (FMOC-Cl) as the derived agent of pre-column was used. The results showed that the best condition of derivatization and RP-HPLC detection was 0.05mol/L HCl, FMOC-Cl and pH 8.50 borate buffer solution as DNJ extract reagent, derivatization reagent and derivatiztion buffer, respectively. The best RP-HPLC-UV mobile phase, whose DNJ-FMOC peak area and DNJ concentration are high positive correlative and the correlation coefficient is 0.9852, was acetonitrile:0.1%-acetic acid (55:45, V/V).And then, the DNJ contents of 132 species of mulberry varieties were investigated. The results showed that the mean value was 0.07511% and standard deviation was 0.028428. The DNJ content of Zu-Chang 2 was the highest (0.14720%) and the lowest one was Guanyin-Sang (0.01341%). In addition, the DNJ contents of different site of mulberry leaves were not same. Accroding to growth degree of the mulberry leaves, the content of DNJ decreased gradually from the upper to lower sites.Accroding to the results and other screening facters, the final mulberry leaf material was selected. Using the material and ultrasonic treatment combined with ethanol, the DNJ purity of crude extracts is 1.2842%. After a series of purification, including macroporous resin (3.3452%), cation exchange resin (12.3873%) and silica resin, the purity of DNJ reached 19.0857%, which conforms to the requirements as a food additive.To evalue the diabetes inhibition role of long-term DNJ treatmen, diabetic mice were fed with DNJ-included dite and compared with those fed with acarbose and normal diet. After 40 days, blood glucose of high dose (40mg/kg) of DNJ mice reduced significantly, and the difference between them and mice fed with the normal diet is significant. The difference of low dose (20mg/kg) and medium dose (30mg/kg) of DNJ treatment mice group compared with control group is not significant.