The Studies On The Extraction, Purification And Content Determination Of DNJ From Mulberry Leaves

DNJ was obtained from mulberry leaves extracted with distilled water in this experiment. The DNJ was purified through cation exchanger column chromatography. The content of DNJ in mulberry leaves was determined by spectrophotometry. The contents of DNJ in mulberry leaf samples collected with different pH value segments were compared. The contents of DNJ in mulberry leaf samples before and after purification, different seasons, and different leaf orders were measured. The result showed that it is advisable to determine the DNJ content in mulberry leaves by spectrophtometry. The content of DNJ in the mulberry leaf samples with different pH value segments, before and after purification, different seasons and different leaf orders had some difference. The whole experiment was composed of seven parts. (1) Determination of DNJ content by spectrophotometryIt is necessary to select the special absorbance wavelength of DNJ before you determine the content of DNJ in mulberry leaves by spectrophotometry. There is no UV or visible spectrum absorbance of DNJ, so it is necessary to add to reagent to show color. The iodine-potassium iodide solution was selected as the reagent to show color in this experiment. After the iodine-potassium iodide solution was added to the DNJ standard sample, the corresponding absorbency of different wavelength was determined in the wavelength range of 300nm~450nm, with the mixture of iodine-potassium iodide solution and water as the blank. Then an absorbencyspectrum curve was obtained. The special absorbance wavelength was determined as 334nm according to the absorbency spectrum curve and Lambert-Beer Law.The DNJ standard sample was dissolved into the distilled water to make the standard solution with the concentration of 0.1mg/ml. The DNJ solution with different concentration grads was put into the tubes, the iodine-potassium iodide solution and distilled water were added, too, then mixed them evenly. The absorbency of solutionin each tube was measured in 334nm with the mixture of iodine-potassium iodide solution and distilled water as the blank. Make the standard curve of DNJ with the concentration of DNJ standard solution as abscissa and the corresponding absorbency as vertical coordinate. The result showed that the absorbency of solution and DNJ concentration submitted direct ratio in certain concentration ranges of DNJ, which accorded with the Lambert-Beer Law. So the content of DNJ in mulberry leaves could be measured by spectrophotometry.(2) Extraction of DNJ in the mulberry leaves60g dried mulberry leaves were put into distillation flask, and the distilled water was added to extract for 2 hours. Then they were secondly extracted with water. The two parts of extracted solutions were filtrated after gathered. The filtrated solution was concentrated with heat to a certainty volume. The extracted solutions of DNJ in mulberry leaves were obtained.(3) Purification of DNJ in the mulberry leavesThe extracted solution of DNJ was exchanged through cation exchanger column chromatography to purify the DNJ. That is to say, after the disposal of exchanger, installing cation exchanger into column, submitting, washing and collecting, concentrating and so on , the purified mulberry leaf sample containing DNJ was obtained. It was weak brown-yellow powder.(4) Determination of DNJ content in mulberry leaves collected with different pH value segmentsThe mulberry leaf extractions were exchanged through cation exchange column chromatography to be purified. It was collected with different pH value segments. It was dissolved into distilled water to make solution after it was dried. Then the DNJ content was measured. The result showed that, the collected solution of pH 9.4-10.5 contained DNJ, the DNJ content of mulberry leaves was 0.024% and the DNJ content in purified samples was 2.22% which was 10 times of that in mulberry leaves. However, the collected solution of other two pH value segments (pH 3-7 pH 7-9.4) contained no DNJ.(5) Comparison of DNJ content in mulberry leav...