MICROWAVE-ASSISTED HYDROLYZATION OF THE FLAVONOIDS IN EPIMEDIUM KOREAMUM NAKAI

In the present paper, icariside I has been prepared by hydrolyzing the flavonoids extract of Epimedium Koreamum Nakai in acid solution. Two heating methods, reflux and microwave irradiation, were used in the hydrolysis reaction and hydrolyzed products were analyzed by high performance liquid chromatography-diode array detection-electrospray ionization tandem mass spectometry (HPLC-DAD-ESI-MSn). The four flavonoids in the extracts have been identified as epimedin A, epimedin B, epimedin C, and icariin, and the hydrolysis product was icariside I. Icariside I has been evaluated by comparing with the peak areas of HPLC-DAD spectra obtained using different heating methods. The experimental results demonstrate that the advantage of microwave irradiation over conventional reflux is validated, and the hydrolysis time is dramatically reduced, and the yield of icariside I is effectively improved. Also, optimum conditions for microwave hydrolysis are established. As a result, the optimum yield of icariside I can be reached under the following conditions: the reaction temperature is 70°C; the microwave irradiation power is 600 W; and the microwave irradiation time is 10 min. The optimum yield by this method was (300.46 ± 0.41 µg), which was 2.3 times more than the classical way (128 ± 0.86 µg). In view of the efficiency, energy saving, and environmental protection in the procedures of microwave-assisted hydrolyzation, this method will have a bright future in the industrial application.