Acid hydrolytic method for determination of ginkgo biloba total flavonoids in rat plasma by HPLC for pharmacokinetic studies

A simple, reliable, economical method was developed using HPLC with a diode-array detector for determination of total flavonoids in plasma after introvenous administration of ginkgo bilobaextract. The method simultaneously detects quercetin, kaempferol, and isorhamnetin after acid hydrolysis and recalculation. The hydrolysis and extraction conditions were optimized in an orthogonal test. The specificity was tested by comparing the retention time, UV spectra, and peak purity indices with standards. The detection limits were 20 ng/mL was quercetin, 20 ng/mL for kaempferol, and 50 ng/mL for isorhamnetin. The calibration curve ranges were 75–2400, 71–2280, and 70–2240 ng/mL. The pharmacokinetic characteristics of ginkgo bilobaflavonoids after venous administration of 50 mg/kg ginkgo bilobaextract to rats were analyzed using a two-compartment model. The initial plasma concentration was 171.22 μg/mL. The half-life of flavonoids in the first compartment (distribution) was 0.07 h and at the second compartment (elimination) was 4.51 h, while the AUC(o-∞)was 1711.06 μg·min/mL. The apparent volume of distribution was 0.11 L/kg. The total body clearance is 10.52 mL/(min;kg). The result shows the method is suitable for pharmacokinetic studies.