Polyphenols from Ginkgo biloba

Fadi Qa’Dan

doi:10.3797/scipharm.1003-19

Abstract

By Sephadex LH-20 gel chromatography of an extract from Gingko biloba leaves, polymeric proanthocyanidins were eluted after the fractions of flavonol glycosides and biflavone glycosides. A purified proanthocyanidin polymer accounted for 86.6% of the total proanthocyanidins, and for 37.7% of the total antioxidant activity of this leaf extract. For structure elucidation, the polymer was submitted to acidic depolymerization in the presence of phloroglucinol. The structures of the resulting flavan-3-ols and phloroglucinol adducts were determined on the basis of 1D-and reverse 2D-NMR (HSQC, HMBC) spectra of their peracetylated derivatives, MALDI-TOF-MS and CD-spectroscopy. The observations resulting from the degradation with phloroglucinol were confirmed by 13C-NMR spectroscopy of the polymer. The mean molecular weight of the polymeric fraction was estimated to be 9–10 flavan-3-ol-units.

Highlights

Extracts of Ginkgo biloba L. (Maidenhair tree, Ginkgoaceae) are widely used in herbal medicine for the treatment of mild to moderate cognitive disorders, concentration problems, tinnitus and dementia [1]
A purified proanthocyanidin polymer accounted for 86.6% of the total proanthocyanidins, and for 37.7% of the total antioxidant activity of this leaf extract
Our study focused on the isolation and characterization of a fraction containing polymeric proanthocyanidins (AWF) from Ginkgo biloba by degradation with phloroglucinol and identification of the break-down products

Summary

Introduction

Extracts of Ginkgo biloba L. (Maidenhair tree, Ginkgoaceae) are widely used in herbal medicine for the treatment of mild to moderate cognitive disorders, concentration problems, tinnitus and dementia [1]. The structures of the resulting flavan-3-ols and phloroglucinol adducts were determined on the basis of 1D-and reverse 2D-NMR (HSQC, HMBC) spectra of their peracetylated derivatives, MALDI-TOF-MS and CD-spectroscopy.

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Results

Conclusion