Efficient 1H nuclear magnetic resonance method for improved quality control analyses of Ginkgo constituents

We developed an analytical method using 1H nuclear magnetic resonance (NMR) spectrometry to resolve analytical problems with Ginkgo. After a simple hydrolysis step, an NMR analysis of the terpene trilactone H-12 signals and the flavonol aglycone H-2' (or H-2'/6' for kaempferol) signals was performed. By comparing the solvent effects on the resolution of these signals, methanol-d4-benzene-d6 (65:35) was selected as the optimal 1H NMR solvent. The amounts of terpene lactones and flavonol aglycones in various commercial Ginkgo products and Ginkgo leaves were determined. This newly developed 1H NMR method enables the simultaneous analysis of terpene trilactones and flavonols and allows simple, rapid quantification of these compounds in pharmaceutical Ginkgo preparations.