Method for preparing ginkgo extracts having a low content of 4'-O-methyl pyridoxine and/or biflavones

Abstract

The present invention relates to an improved multi-step method for preparing an extract from ginkgo biloba having a reduced content of 4′-O-methyl pyridoxine and/or biflavones, wherein the depletion is carried out by filtration over an adsorber resin and/or an ion exchanger and the substances to be removed are retained on the resin. The invention further relates to an extract from ginkgo biloba having a reduced content of 4′-O-methyl pyridoxine and/or biflavones, which is obtainable by the method according to the present invention, as well as to its use.

1 - 15 . (canceled)  
   
   
       16 . A method for producing an extract from ginkgo biloba having a reduced content of 4′-O-methyl pyridoxine and/or biflavones, the method comprising: 
 a) extracting leaves of ginkgo biloba using water-containing acetone, a water-containing alkanol having 1 to 3 carbon atoms or anhydrous methanol,    b) separating the organic solvent by concentrating the solvent to a content of 10% by weight at the most, wherein water may be added during the final distillation steps,    c) diluting the remaining aqueous solution with water to a solids content of 5 to 25% by weight, cooling to a temperature below 25° C. and allowing to stand until a precipitate is formed,    d) treating the remaining aqueous solution with ammonium sulfate and subsequently extracting at least once using methyl ethyl ketone or a mixture of methyl ethyl ketone and acetone,    e) concentrating the extract obtained and diluting with an ethanol-water mixture to obtain a solution containing 50% by weight water and 50% by weight ethanol at a solids content of 10% by weight,    f) treating the solution with a lead compound or an insoluble polyamide,    g) extracting the filtered solution using an aliphatic or cycloaliphatic solvent having a boiling point of 60 to 100° C.,    h) concentrating the remaining aqueous-alcoholic solution, followed by treating with ammonium sulfate and extracting with methyl ethyl ketone and ethanol,    i) concentrating the organic phase obtained to a solids content of 50 to 70% by weight,    k) dissolving the concentrate in an aqueous alkanol having 1 to 3 carbon atoms and optionally filtering,    l) filtration over an adsorber resin and/or an ion exchanger, wherein the substances to be removed are retained on the resin and    m) drying the concentrate at reduced pressure to obtain a dry extract having a water content of less than 5%.    
   
   
       17 . A method of  claim 16  wherein the aqueous alkanol in step k) is aqueous ethanol.  
   
   
       18 . A method of  claim 17  wherein the aqueous ethanol is ethanol having a content of 40 to 60% by weight.  
   
   
       19 . A method of  claim 16  wherein the adsorber resin in step l) is a resin based on optionally substituted one or more styrene and/or /divinylbenzene.  
   
   
       20 . A method of  claim 16  wherein the ion exchanger in step l) is a strongly acidic ion exchanger.  
   
   
       21 . An extract obtainable from leaves of ginkgo biloba, wherein the extract has less than 20 ppm 4′-O-methyl pyridoxine and/or less than 20 ppm biflavones.  
   
   
       22 . An extract of  claim 21  wherein the extract comprises less than 10 ppm 4′-O-methyl pyridoxine.  
   
   
       23 . An extract of  claim 21  wherein the extract comprises less than 2 ppm 4′-O-methyl pyridoxine.  
   
   
       24 . An extract of  claim 21  wherein the extract comprises less than 10 ppm biflavones.  
   
   
       25 . An extract of  claim 21  wherein the extract comprises less than 5 ppm biflavones.  
   
   
       26 . An extract of  claim 21  wherein the extract comprises (i) 20 to 30% by weight flavonoids, (ii) 4.5 to 8.5% by weight terpene lactones and (iii) less than 10 ppm ginkgolic acids.  
   
   
       27 . An extract of  claim 21  wherein the extract comprises (i) 22.0 to 27.0% by weight flavonoids, (ii) 5.0 to 7.0% by weight terpene lactones and (iii) up to 5 ppm ginkgolic acids.  
   
   
       28 . An extract of  claim 21  wherein the extract comprises (i) 22.0 to 27.0% by weight flavonoids, (ii) 2.8 to 3.4% by weight ginkgolides A, B and C in total, (iii) 2.6 to 3.2% by weight bilobalid and (iv) up to 5 ppm ginkgolic acids.  
   
   
       29 . A method of treating a subject suffering from or susceptible to dementia and one or more symptoms thereof and/or a cerebral or peripheral blood circulation disorder, comprising administering to the subject an extract of  claim 21 .  
   
   
       30 . A method of  claim 29  wherein the subject is suffering from dementia and one or more symptoms thereof and/or a cerebral or peripheral blood circulation disorder.  
   
   
       31 . A method of  claim 29  wherein the subject is suffering from dementia.  
   
   
       32 . A method of  claim 29  wherein the subject is suffering from a cerebral or peripheral blood circulation disorder.  
   
   
       33 . A method of  claim 29  wherein the subject is identified as suffering from dementia and one or more symptoms thereof and/or a cerebral or peripheral blood circulation disorder and the extract is administered to the identified subject.  
   
   
       34 . A medicament, food product or other preparation comprising a Gingko extract of  claim 21 .  
   
   
       35 . A method for producing an extract from ginkgo biloba having a reduced content of 4′-O-methyl pyridoxine and/or biflavones, the method comprising: 
 a) extracting leaves of ginkgo biloba using water-containing acetone, a water-containing alkanol having 1 to 3 carbon atoms or anhydrous methanol,    b) separating the organic solvent by concentrating the solvent to a content of up to 10% by weight,    c) diluting the remaining aqueous solution with water to a solids content of 5 to 25% by weight, and allowing to stand until a precipitate is formed,    d) treating the remaining aqueous solution with ammonium sulfate and subsequently extracting at least once using methyl ethyl ketone or a mixture of methyl ethyl ketone and acetone,    e) concentrating the extract obtained and diluting with an ethanol-water mixture to obtain a solution having a solids content of 10% by weight,    f) treating the solution with a lead compound or an insoluble polyamide,    g) extracting the solution using an aliphatic or cycloaliphatic solvent,    h) concentrating the remaining aqueous-alcoholic solution, followed by treating with ammonium sulfate and extracting with methyl ethyl ketone and ethanol,    i) concentrating the organic phase obtained to a solids content of 50 to 70% by weight,    k) dissolving the concentrate in an aqueous alkanol having 1 to 3 carbon atoms and optionally filtering,    l) filtering over an adsorber resin and/or an ion exchanger, and    m) drying the concentrate at reduced pressure to obtain a dry extract having a water content of less than 5%.