title: Adulteration of Ginkgo biloba products and a simple method to improve its detection.
abstract: Extracts of ginkgo (Ginkgo biloba) leaf are widely available worldwide in herbal medicinal products, dietary supplements, botanicals and complementary medicines, and several pharmacopoeias contain monographs for ginkgo leaf, leaf extract and finished products. Being a high-value botanical commodity, ginkgo extracts may be the subject of economically motivated adulteration. We analysed eight ginkgo leaf retail products purchased in Australia and Denmark and found compelling evidence of adulteration with flavonol aglycones in three of these. The same three products also contained genistein, an isoflavone that does not occur in ginkgo leaf. Although the United States Pharmacopeia - National Formulary (USP-NF) and the British and European Pharmacopoeias stipulate a required range for flavonol glycosides in ginkgo extract, the prescribed assays quantify flavonol aglycones. This means that these pharmacopoeial methods are not capable of detecting adulteration of ginkgo extract with free flavonol aglycones. We propose a simple modification of the USP-NF method that addresses this problem: by assaying for flavonol aglycones pre and post hydrolysis the content of flavonol glycosides can be accurately estimated via a simple calculation. We also recommend a maximum limit be set for free flavonol aglycones in ginkgo extract.
authors.affiliation: Medicinal Plant Herbarium, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia; Integria Healthcare, Gallans Road, Ballina, NSW 2478, Australia. Electronic address: hans.wohlmuth@scu.edu.au.
authors.forename: Hans
authors.initials: H
authors.lastname: Wohlmuth
authors.affiliation: Southern Cross Plant Science, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia.
authors.forename: Kate
authors.initials: K
authors.lastname: Savage
authors.affiliation: Southern Cross Plant Science, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia.
authors.forename: Ashley
authors.initials: A
authors.lastname: Dowell
authors.affiliation: Medicinal Plant Herbarium, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia; Southern Cross Plant Science, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Mouatt
mesh_terms: D001315:Australia; D002851:Chromatography, High Pressure Liquid; D003132:Commerce; D003718:Denmark; D019587:Dietary Supplements; D004340:Drug Contamination; D044948:Flavonols / Q000032:analysis*; D019833:Genistein / Q000032:analysis*; D020441:Ginkgo biloba / Q000737:chemistry*; D006027:Glycosides / Q000032:analysis*; D010602:Pharmacopoeias as Topic; D010936:Plant Extracts / Q000737:chemistry*; D018515:Plant Leaves
chemical_list: D044948:Flavonols; D006027:Glycosides; D010936:Plant Extracts; D019833:Genistein
keywords: Adulteration; Genistein; Ginkgo biloba; Ginkgo extract; Ginkgo flavonol glycosides; Quality control