Method for obtaining an extract or Ginkgo biloba leaves

摘要

The present invention relates to a novel method for obtaining an extract of Ginkgo biloba leaves. In the method according to the invention, the following successive operations are performed: grinding of the Ginkgo biloba leaves; extraction of the ground preparation of Ginkgo biloba leaves using an aqueous ketone solvent; concentration of the extraction liquors in order to precipitate the biflavonoids and the hydrophobic substances; filtration of the aqueous concentrate; alkalinization of the filtrate so as to precipitate the proanthocyanidins; removal by filtration of the insoluble fraction containing the proanthocyanidins; acidification of the filtrate; liquid-liquid extraction of the filtrate with a C4-C6 ketone in the presence of ammonium sulfate; and recovery of the extract by taking the ketone phase to dryness.