The aim of the present study was to evaluate quantitative analysis of flavonoid aglycones in Ginkgo biloba Extract (GBE)
by an optimized flavonol glycoside hydrolysis condition A 4 factor, 5 level
central composite design was used for the
optimization hydrolysis condition with the amounts of methanol ( X 1 ), the amounts of 25% HCl ( X 2 ), hydrolysis time ( X 3 ), and hydrolysis temperature ( X 4 ) as the independent variables The response variable was the percentage of flavonoid aglycones in GBE Different percentages of flavonoid aglycones were obtained The percentage ranged from 13 44% to 27 62% The results reveal that all the factors and their variable amounts could greatly affect the accuracy of the quantitative analysis of flavonol aglycones in GBE Mathematical equations and response surface plots were used to relate the dependent and independent variables The regression equation generated for the percentage of flavonoid aglycones in GBE was Y =5 305037+5 289754 X 1 +2 941849 X 2 +0 460816 X 3 -2 19615 X 4 +2 799579 X 1 2 -1 81609 X 2 2 -0 030106 X 3 2 +0 037508 X 4 2 +4 810418 X 1 X 2 + 0 248037 X 1 X 3 -1 44954 X 1 X 4 -1 21092 X 2 X 3 + 1 455291 X 2 X 4 + 0 097479 X 3 X 4 -0 927236 X 1 2 X 2 + 0 033193 X 1 2 X 3 -0 065871 X 1 2 X 4 +2 293473 X 2 2 X 1 -0 080708 X 2 2 X 3 -0 143044 X 2 2 X 4 -0 003852 X 3 2 X 1 +0 007604 X 3 2 X 2 +0 000698 X 3 2 X 4 + 0 019766 X 4 2 X 1 -0 007261 X 4 2 X 2 -0 001888 X 4 2 X 3 -0 001061 X 1 X 2 X 3 +0 011974 X 1 X 2 X 4 - 0 000005 X 1 X 3 X 4 -0 000437 X 2 X 3 X 4 The observed responses were in close agreement with the predicted values of the optimized formulation This demonstrated the reliability of the optimization procedure The average recoveries of quercetin, kaempferol and isorhamnetin is above 98 5%, respectively The optimal condition for acid hydrolysis of flavonoid glycosides in Ginkgo biloba extract could be achieved by refluxing 25 mg GBE with 4 2 ml 25% HCl and 12 ml methanol at 75 ℃ for 100 minutes