SELECTIVE ADSORPTION OF FLAVONOID COMPOUNDS FROM THE LEAF EXTRACT OF GINKGO-BILOBA L

A simple purification method has been developed in which flavonoid com pounds are selectively adsorbed onto a polycarboxyl ester resin (XAD-7 ) from methanol extract of ginkgo leaves. When 1.0 g dried gingko leav es was extracted with 100 ml of methanol, about 98% of total flavonoid compounds was recovered by selective adsorption. The pH did not affec t the adsorption of flavonoids but at high pH the chemical structure o f flavonoids was changed and the adsorption decreased to almost zero. As the solution polarity played a key role in the selective adsorption , the amount of water added to the methanol extract was critical for t he recovery and loading of flavonoids. Using standard flavonoids, kaem pferol and quercetin, the optimal water content was 80% and the recove ry was 80% with 10g of resin dosage/l.