title: Evaluation of a method to determine flavonol aglycones in Ginkgo biloba dietary supplement crude materials and finished products by high-performance liquid chromatography: collaborative study.
abstract: An interlaboratory study was conducted for evaluation of a method to determine the flavonol aglycones quercetin, kaempferol, and isorhamnetin in Ginkgo biloba products. The method calculates total glycosides based on these aglycones formed after acid hydrolysis. Twelve matrixes were chosen for study by 12 collaborating laboratories in 2 countries. Test materials included crude leaf material, standardized dry powder extract, single and multiple entity finished products, ethanol and glycerol tinctures, and National Institute of Standards and Technology (NIST) standard reference materials (SRMs). Results from 11 laboratories were used for the final calculations. Eight of the 12 matrixes evaluated produced acceptable results for total flavonol glycosides, with HorRat scores ranging from 1.31 to 2.05; repeatability relative standard deviations (RSDr) from 1.46 to 4.14; and reproducibility relative standard deviations (RSDR) from 4.67 to 9.69. These 8 matrixes consisted primarily of simple dosage forms (e.g., dry powder extracts, crude leaf samples, liquid extracts, and SRMs) and a single tablet product (Ginkgo Awareness). Four additional matrixes, consisting of 3 tablets and 1 soft gel product (Ginkgold, Ginkoba, Ginkogen, and Ginkgo Phytosome, respectively), showed greater total flavonol glycoside HorRat scores in comparison, ranging from 2.39 to 5.13, with RSDr values from 2.83 to 8.16, and RSDR values from 8.53 to 20.4. Based on the results presented here, the method is recommended for Official First Action for determination of total flavonol glycosides calculated from quercetin, kaempferol, and isorhamnetin in dry powder extracts, crude leaf material, liquid extracts, and a select finished product, Ginkgo Awareness.
authors: Midwest Research Institute, 425 Volker Blvd, Kansas City, MO 64110-2299, USA. dgray@mriresearch.org
authors: Dean
authors: D
authors: Gray
authors: Kerri
authors: K
authors: LeVanseler
authors: Pan
authors: P
authors: Meide
authors: Edward H
authors: EH
authors: Waysek
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002853:Chromatography, Liquid / Q000379:methods; D019587:Dietary Supplements; D044948:Flavonols / Q000032:analysis*; D020441:Ginkgo biloba / Q000737:chemistry*; D044949:Kaempferols / Q000032:analysis*; D007753:Laboratories / Q000592:standards; D018515:Plant Leaves / Q000737:chemistry; D011794:Quercetin / Q000032:analysis* / Q000031:analogs & derivatives; D012015:Reference Standards; D013594:Syringes
chemical_list: D044948:Flavonols; D044949:Kaempferols; C047368:3-methylquercetin; C006552:kaempferol; D011794:Quercetin