Possible adulterations of Ginkgo biloba food supplements

Products containing the standardized Ginkgo biloba L. (Ginkgoaceae) leaves extract, EGb 761, are used for the “improvement of cognitive impairment and of quality of life in mild dementia” (EMA-HMPC). The herbal drug Ginkgonis folium is used for the treatment of peripheral circulation disorders. Ginkgonis extractum siccum raffinatum et quantificatum (Ph. Eur. 8) shall contain 22%-24% flavonoids, and 5.4%-6.6% terpene lactones (ginkgolides, bilobalide). Next to mass products (medicines), some food supplements also contain the EGb 761 extract. The aim of this work was to prove whether food supplements possess pharmaceutical quality, and if they even obey the European Pharmacopoeia criteria. The experimental part is focused on the quantification of two groups of secondary metabolites in 3 mass product medicines (positive control), and in 11 food supplements containing EGb 761 or Ginkgonis folium. Flavonoids were quantified with and without aglycone hydrolysis using HPLC-UV. Terpene lactones (diterpenes – ginkgolides A, B, C, and the pentanorditerpene bilobalide) were quantified using LC-MS/MS. Microscopic analysis was included as well. The medicine mass products contained 29.06%-32.04% of flavonoids, whereas the food supplements just 0.2 to 39.79%, expressed as acylglycoside (Mr 756.7). The medicine mass products contained 5.22%-5.63% ginkgolides, and 4.52%-6.59% bilobalide, i.e. they meet the Ph. Eur. 8 requirements. Dietary supplements contained 0.00 to 29.66% ginkgolides, and 0.00%-13.44% bilobalide. One dietary supplement did not contain any Ginkgo, the presence of other herbal drugs was confirmed microscopically. Our results suggest that many Ginkgo food supplements are not of pharmaceutical quality, neither do they satisfy the requirements for medicines. Only two of 11 dietary supplements met the Ph. Eur. 8 requirements (lege artis), some used an adulterated extract, and two did not contain any Ginkgo herbal drug or extract.