Optimization of the Extraction and Purification Technologies of Total Flavonoids from Diospyros kaki Thunb. Leaves and Comparison of the Contents of Total Flavonoids in Fresh and Dried Diospyros kaki Thunb. Leaves / 中国药房

ABSTRACT

OBJECTIVE:To optimize the parameters of the extraction and purification technologies of total flavonoids from Di-ospyros kaki Thunb. leaves,and then to compare the contents of flavonoids in fresh and dried D. kaki Thunb. leaves. METHODS:Taking the yield of total flavonoids as the investigated index,the influences of liquid-solid ratio,the volume fraction of ethanol and ultrasonic extraction time on the extraction effect were discussed by single-factor and orthogonal test. With the purity of total flavo-noids as the investigated index,the purification effects of such three kinds of methods as ethyl acetate extraction method,alcohol deposition method and macroreticular resin purification method combined with petroleum ether degreasing on the extracted solution were compared. The optimal extraction technology was adopted to extract the total flavonoids from fresh and dried D. kaki Thunb. leaves and their contents were compared. RESULTS:The optimal extraction technology was as follows as liquid-solid ratio of 25∶1 (ml/g),volume fraction of ethanol of 70%,ultrasonic extraction time of 30 min,extraction temperature of 30 ℃. The results of the verification tests showed the average content of total flavonoids was 1.75%(RSD=2.00%,n=3). The total flavonoids in the extracted solution purified by the above-mentioned three purification methods had a purity of 24.92%,15.94% and 35.52% respec-tively,in which the macroreticular resin purification method with petroleum ether degreasing combined with AB-8 resin purification was optimal. The content of flavonoids in fresh D. kaki Thunb. leaves(1.75%) was about twice as much as that in dried leaves (0.87%). CONCLUSIONS:The optimal extraction and purification technologies are simple with good effect,and suitable for large-scale production. Fresh D. kaki Thunb. leaves should be used as raw materials for extracting flavonoids.