Rapid Determination of Terpene Lactones and Flavonoids in Commercial Extracts of Ginkgo biloba L. Leaves using UPLC-UV-ELSD/MS

Ginkgo biloba L. is a botanical ingredient used to help support brain function and memory and has become one of America's most popular dietary supplements. Clinically studied standardized extracts of G. biloba leaves are reported to contain not less than 6% terpene lactones (including ginkgolides and bilobalide), and 24% of flavone glycosides (primarily composed of quercetin, kaempferol, and isorhamnetin glycosides) [1,2]. Analysis of both terpene lactones and flavone glycosides in G. biloba usually involves a two step process as each class of compounds requires a separate analysis. In order to simplify this analysis, a new rapid Ultra Performance Liquid Chromatography (UPLC-UV-ELSD/MS) method has been developed for the simultaneous determination of five terpene lactones [bilobalide (BB), ginkgolide J (GJ), ginkgolide C (GC), ginkgolide A (GA) and ginkgolide B (GB)] and three flavonoid glycosides (quercetin, isorhamnetin and kaempferol) from commercial extracts of G biloba leaves. The chromatographic separation by UPLC was achieved using a reversed phase (RP-18) column and a water/methanol:isobutanol (9:1) gradient containing 0.5% formic acid. The terpene lactones, which have low UV absorption, were detected by evaporative light scattering detector (ELSD) while flavonoid glycosides were detected with photo diode array (PDA). The wavelength used for determination of flavonoids with the PDA detector was 370nm. LC-MS coupled with electrospray ionization (ESI) was used for the identification of eight compounds in gingko. This method involved the use of the [M+Na]⁺ and [M+H]⁺ ions for eight compounds in the positive ion mode with selected ion monitoring (SIR). The developed method is simple, economic, and rapid and especially suitable for simultaneous analysis of total terpene lactones, flavonoid glycosides, and other individual components, for quality control of standardized extracts of G. biloba leaves.

Fig.1 UPLC-UV-ELSD chromatograms of standard mix (A) and leaves sample (B) using PDA detector at 370nm and ELSD (1) BB, (2) GJ, (3) GC, (4) GA, (5) GB, (6) quercetin, (7) isorhamnetin and (8) kaempferol

Acknowledgements: This research is supported in part by the Global Science, Product Safety and Compliance, Herbalife International of America, Torrance, CA 90502, USA, and the United States Department of Agriculture, Agricultural Research Service, Specific Cooperative Agreement No. 58–6408–2-0009 and the authors would like to thank Annette Ford for the extractions of plant samples.

References: [1] Khan IA, Abourashed EA (2009) Leung's Encyclopedia of Common Natural Ingredients used in Food, Drugs and Cosmetics. 3rd Edition. Wiley & Sons, Inc., Publication, USA, [2] Mauri P, et al. (1999)J Mass Spectrom, 34: 1361–1367.