The Fingerprint-quantitative Study Of Ginkgo Flavonoides By NMR Method

Flavonoides and ginkgolides are the most important active materials in gingko leaves. For flavonoides, which consist of more than forty glycosides, quercetin, kaempferol and isohamnetin are the main elements. Standardized gingko bilobal extractant (GBE) was brought forward by a Germany scientist. The criteria for the regular GBE in medical industry include two aspects: the content of flavonoides is more than 24 percent and inner-ester 6 percent. During the year 1992 to 1993, Hasler developed a qualitative-quantitative method to determine the contents of five flavonoide glycosides and the contents of the above-mentioned three monomers are the criteria for the production of flavonoides.1.Quercetin, kaempferol and isohamnetin, the main product of the hydrolysis of flavonoides, are very similar in their structure. The three glycosides' chemical shifts, self-spin systems and coupling constants in their NMR spectra are thoroughly investigated and their fingerprint spectra characteristics, especially at the special chemical shift range in the DMSO-D6 solvent system, are confirmed or speculated.2.An optimized hydrolysis procedure of GBE's flavonoides is achieved through the ultraviolet spectra, infrared spectra and NMR spectra analysis of GBE and quercetin and their hydrolysis products. The ultraviolet method is speedy and convenient but less precise with few spectra signals. Though with more spectra signals, the infrared method cannot distinguish quercetin from its acidic hydrolysis product. While little kaempferol and isohamnetin can be discerned in the NMR spectra which is the most important and efficient method for the structural analysis of organic compounds.3. NMR's one and two dimension 'H-NMR, 13C-NMR, 'H-'H COSY, HMQC, HMBC and multi-pulse DEPT spectra are applied to the fingerprint analysis of GBE's flavonoides. The fingerprint technique confirmed that dissociative quercetin, aempferol and isorhamnetin are the major products of GBE's flavonoides mixture, which for the first time develops a useful method for the fingerprint and quantitative analysis of GBE' s Flavonoides mixture.4. According to the integral curves of 'H-NMR spectra, the relative content of quercetin, kaempferol and isohamnetin is 88.71%, 6.35% and 4.94% respectively after the hydrolysis of GBE, which is the initial quantitative analysis of GBE's flavonoides mixture utilizing 'H-NMR method.