Method for Isolation of Cytisine

Abstract

A method for isolating cytisine from plant material includes dissolving the plant material in an alcohol to form a liquid mixture and acidifying the liquid mixture by addition of an acid. The method also includes concentrating the liquid mixture to form a concentrated aqueous solution and extracting the concentrated aqueous solution with a first extractant to form a purified aqueous concentrate. The method includes alkalizing the purified aqueous concentrate with an alkalizing agent to form an alkaline aqueous concentrate. The method further includes extracting the alkaline aqueous concentrate with a second extractant and removing the second extractant to obtain cytisine.

We claim: 
     
         1 . A method for isolating cytisine from plant material, the method comprising:
 (a) dissolving the plant material in an alcohol to form a liquid mixture;   (b) acidifying the liquid mixture by addition of an acid;   (c) concentrating the liquid mixture to form a concentrated aqueous solution;   (d) extracting the concentrated aqueous solution with a first extractant to form a purified aqueous concentrate;   (e) alkalizing the purified aqueous concentrate with an alkalizing agent to form an alkaline aqueous concentrate;   (f) extracting the alkaline aqueous concentrate with a second extractant; and   (g) removing the second extractant to obtain cytisine.   
     
     
         2 . The method of  claim 1 , further comprising crystallizing cytisine in an organic solvent. 
     
     
         3 . The method of  claim 2 , wherein crystallizing further comprises filtering cytisine from the organic solvent. 
     
     
         4 . The method of  claim 3 , wherein the organic solvent is acetone or ethyl acetate. 
     
     
         5 . The method of  claim 1 , further comprising filtering the liquid mixture after concentrating. 
     
     
         6 . The method of  claim 1 , wherein extracting the concentrated aqueous solution with the first extractant comprises adding the first extractant, wherein a ratio of the concentrated aqueous solution to the first extractant is 1:1. 
     
     
         7 . The method of  claim 1 , wherein extracting the alkaline aqueous concentrate with the second extractant comprises adding the second extractant, wherein a ratio of the alkaline aqueous concentrate to the second extractant is about 1:5 to about 1:10. 
     
     
         8 . The method of  claim 1 , wherein the alcohol is methanol or ethanol. 
     
     
         9 . The method of  claim 1 , wherein a pH of the liquid mixture after acidification is between about 1.5 and about 3.5. 
     
     
         10 . The method of  claim 1 , wherein the acid includes sulfuric acid or hydrochloric acid. 
     
     
         11 . The method of  claim 1 , wherein the first extractant and the second extractant are independently selected from chloroform, methylene chloride, butyl acetate, and n-butanol. 
     
     
         12 . The method of  claim 1 , wherein the alkalizing agent is sodium hydroxide or ammonium hydroxide. 
     
     
         13 . The method of  claim 1 , wherein a pH of the purified aqueous concentrate is about 9 to about 12 after addition of the alkalizing agent. 
     
     
         14 . The method of  claim 1 , wherein cytisine is obtained at a purity of at least about 98%. 
     
     
         15 . The method of  claim 14 , wherein cytisine is obtained at a purity of at least about 99%. 
     
     
         16 . The method of  claim 1 , wherein a yield of cytisine is at least about 80%. 
     
     
         17 . The method of  claim 16 , wherein the yield of cytisine is at least about 85%. 
     
     
         18 . The method of  claim 1 , wherein (d) extracting the concentrated aqueous solution with the second extractant to form the purified aqueous concentrate is performed at a temperature ranging from 20° C. to 50° C.