Process for removing pesticides from ginkgo biloba extracts, and extracts obtainable by said process

Abstract

Process for removing pesticides from Ginkgo biloba extracts, which involves submitting an extract obtained by conventional methods to the following steps: a. Liquid-liquid extraction of the extract to obtain a medium polarity fraction containing ginkgo terpenes and pesticides not removable with hexane, and a high polarity fraction containing ginkgo flavone glycosides; b. crystallisation from the medium polarity fraction obtained at step a) to give an intermediate with a ginkgolide content of not less than 50%; c. crystallisation from the residual solution obtained at step b) to give an intermediate with a bilobalide content of not less than 50%; d. mixing of the high polarity fraction obtained at step a) with the ginkgo terpene intermediate and the bilobalide intermediate obtained at steps b) and c).

1 . Extracts obtainable according to a process for removing pesticides from  Ginkgo biloba  extracts, obtained by conventional methods, said process comprising:
 a) subjecting said  Ginkgo biloba  extracts to liquid-liquid extraction to obtain a first fraction containing  ginkgo  terpenes and pesticides not removable with hexane, and a second fraction containing  ginkgo  flavone glycosides;   b) crystallizing the  ginkgo  terpenes from the first fraction obtained at step a) to give a ginkgolide intermediate with a ginkgolide content of not less than 50% w/w and a residual solution;   c) crystallizing the residual solution obtained in step b) to obtain a bilobalide intermediate with a bilobalide content of not less than 50% w/w;   d) mixing the second fraction obtained in step a) with the ginkgolide intermediate and the bilobalide intermediate obtained at steps b) and c) thereby removing said pesticides from said  Ginkgo biloba  extracts.   
     
     
         2 . The extracts as claimed in  claim 1 , wherein the extraction of step a) is carried out with a water-immiscible solvent selected from esters, chlorinated hydrocarbons, mixtures of hydrocarbons and alcohols, ketones and mixtures of ketones and alcohols. 
     
     
         3 . The extracts as claimed in  claim 2  wherein the solvent is an ester having 2 to 8 carbon atoms. 
     
     
         4 . The extracts as claimed in  claim 1  wherein the crystallisation of  ginkgo  terpenes is carried out in mixtures of water and C1-C3 alcohols. 
     
     
         5 . The extracts as claimed in  claim 1  wherein the crystallisation from the terpene-rich fraction of step c) is carried out in water or in a mixture of water and C1-C3 alcohols.