HPLC determination of certain flavonoids and terpene lactones in selected Ginkgo biloba L. phytopharmaceuticals

The biologically active secondary metabolites of Ginkgo biloba extract EGb 761 in phytopharmaceuticals were analyzed using two simple, rapid, accurate and sensitive HPLC methods. The proposed methods were successfully applied in the determination of terpenes and flavonoids in four phytopharmaceutical preparations selected from the Egyptian market. The terpenes; ginkgolide A, ginkgolide B, and bilobalide were analyzed using RP 18 column with a mobile phase consisting of water/methanol/isopropanol (72.5:17.5:10, v/v) at a flow rate of 1 ml min^–1 and UV detection at 220 nm. The flavonoids; quercetin and kaempferol were analyzed using RP 18 column in a step gradient elution with acetonitrile and water at pH 3.3 and flow rate of 1.5 ml min^–1 with UV detection at 370 nm. The two HPLC methods were completely validated.