Qualitative categorization of supplement grade Ginkgo biloba leaf extracts for authenticity

Abstract

Ginkgo biloba, a traditional herbal remedy and a popular functional food is sold commercially in form of a standardized extract for its flavone glycosides content (24%) and terpene lactones (6%). The ginkgo terpene lactones are the unique components of ginkgo leaves unlike the flavone glycosides which are quite common in other botanical extracts. Therefore, flavone glycosides (and their respective aglycones) are the main targets of adulteration of ginkgo extracts to meet the marker levels in the commercially available raw materials in the market. We have investigated the typical quality of a wide variety of commercial ginkgo extracts as well as their potential adulterants. Based on our analytical results we have classified the commercially available extracts of G. biloba into three categories such as authentic, intermediate and adulterated/spiked. A combination of qualitative determination of the unhydrolyzed extracts by phytochemical fingerprinting as well as typical quantitative analysis for total flavone glycosides including Q/K/I (quercetin/kaempferol/isorhamnetin) peak area ratio on hydrolyzed samples is recommended to establish/track the authenticity of the available extracts for formulation purposes.

Keywords

• Ginkgo biloba
• Flavone glycosides
• Quercetin
• Kaempferol
• Isorhamnetin
• Standardized extracts