Process for extracting compounds from plants

Abstract

The present invention provides a method for selectively extracting acidic and/or non-acidic compounds from natural material such as plant tissue.

What is claimed is:  
     
         1 . A method for selectively extracting one or more non-acidic compounds from plant tissue in the presence of one or more acidic compounds, the method comprising: 
 (a) contacting a mixture of a basic component and a first solvent with the plant tissue to immobilize the acidic compound as a salt on the plant tissue; and    (b) contacting the plant tissue with a second solvent suitable to remove the one or more non-acidic compounds;    thereby effectively providing a solution comprising the one or more non-acidic compounds.    
     
     
         2 . The method of  claim 1 , wherein the basic component comprises an alcoholate.  
     
     
         3 . The method of  claim 2 , wherein the alcoholate is an aluminum alcoholate.  
     
     
         4 . The method of  claim 3 , wherein the aluminum alcoholate is aluminum iso-propoxide.  
     
     
         5 . The method of  claim 3  wherein the aluminum alcoholate is aluminum ethoxide or aluminum methoxide.  
     
     
         6 . The method of  claim 1  wherein the basic component comprises an amine of formula NR 3 , wherein each R is independently hydrogen, (C 1 -C 12 )alkyl, aryl (e.g., phenyl), or arylalkyl (e.g., benzyl), wherein each alkyl, aryl (e.g., phenyl), or arylalkyl (e.g., benzyl) can be optionally substituted on carbon with one or more hydroxy, halo, or —N(R b ) 2 ; wherein R b  is H, (C 1 -C 6 )alkyl, aryl (e.g., phenyl), or arylalkyl (e.g., benzyl).  
     
     
         7 . The method of  claim 1  wherein the basic component comprises a heterocycle.  
     
     
         8 . The method of  claim 7  wherein the heterocycle is pyridine, morpholine, piperidine, pyrrole, or pyrrolidine; each optionally subtituted on any suitable carbon with oxo, hydroxy, sulfo, (C 1 -C 4 )alkyl, (C 1 -C 4 )hydroxyalkyl, or —N(R b ) 2 , wherein R b  is H or (C 1 -C 4 )alkyl, or on nitrogen with (C 1 -C 4 )alkyl or (C 1 -C 4 )hydroxyalkyl.  
     
     
         9 . The method of  claim 1  wherein the basic component comprises an alkaline earth metal hydroxide.  
     
     
         10 . The method of  claim 9  wherein the basic component is NaOH, KOH, LiOH, Mg(OH) 2 , Ca(OH) 2 , or a mixture thereof.  
     
     
         11 . The method of  claim 1  wherein the basic component comprises an alkaline earth metal oxide.  
     
     
         12 . The method of  claim 1  wherein the basic component comprises an alkaline earth metal carbonate or an alkaline earth metal bicarbonate.  
     
     
         13 . The method of  claim 12  wherein the basic component is Na 2 CO 3 , K 2 CO 3 , KNaCO 3 , Li 2 CO 3 , CaCO 3 , MgCO 3 , or a mixture thereof.  
     
     
         14 . The method of  claim 1  wherein the basic component comprises an alkaline earth metal sulfite or alkaline earth metal sulfide.  
     
     
         15 . The method of  claim 1 , wherein the first solvent and the second solvent are each independently an optionally substituted aromatic compound, an optionally substituted heterocyclic compound, an optionally substituted cyclic compound, an optionally substituted linear or branched compound, or combination thereof, wherein suitable substituents include (C 1 -C 6 )alkyl, hydroxyl, halo, cyano, nitro, oxo, thioxo, amino, carboxyl, or combinations thereof.  
     
     
         16 . The method of  claim 1 , wherein the first solvent and the second solvent are each independently isopropanol, ethanol, methanol, methylene chloride, toluene, o-xylene, m-xylene, p-xylene, carbon dioxide, Xe, Freon-23, ethane, N 2 O, SF 6 , propane, ammonia, n-C 4 H 10 , (C 2 H 5 ) 2 O, or a combination thereof.  
     
     
         17 . The method of  claim 1 , wherein the first solvent, the second solvent, or a combination thereof, comprises an additive.  
     
     
         18 . The method of  claim 17  wherein the additive is methanol; ethanol; 1-propanol; 2-propanol; 1-hexanol; 2-methoxy ethanol; tetrahydrofuran; 1,4-dioxane; acetonitrile; dichloromethane; ammonia; chloroform; propylene carbonate; N,N-dimethylacetamide; dimethyl sulfoxide; formic acid; water; carbon disulfide; acetone; propane; toluene; hexanes; pentanes; o-xylene; m-xylene; p-xylene; toluene; or a combination thereof.  
     
     
         19 . The method of  claim 1  wherein the plant tissue comprises bark, roots, leaves, flowers, needles, bulbs, berries, rhizomes, rootstocks, stems, seeds, or any combination thereof.  
     
     
         20 . The method of  claim 1  wherein the plant tissue comprises  Taxus yunnanesis  bark, yew tree needles, Echinacea spp. root,  Ginkgo biloba  root bark,  Ginkgo biloba  leaves;  Allium sativum  bulbs,  Valeriana officinalis  root,  Panax ginseng  root, Aloe vera leaves,  Vaccinium macrocarpon  berries,  Eleutherococcus senticosus  root,  Eleutherococcus senticosus  rhizome,  Eleutherococcus senticosus  stems,  Eleutherococcus senticosus  leaves,  Piper methysticum  rootstock, dill seeds, kola nut seeds, cinchona red bark, chinchona yellow bark, or a combination thereof.  
     
     
         21 . The method of  claim 1  wherein the one or more non-acidic compounds comprises lupeol, betulin, taxol, echinacea extract, valerian root extract, ginkgolide A, ginkgolide B, ginkgolide C, bilobalide, garlic extract, ginseng extract, aloe gel, barbaloin, cranberry extract, eleutheroside A, eleutheroside B, eleutheroside C, eleutheroside D, eleutheroside E, eleutheroside G, kava extract, dill seed oil, kola extract, quinoline alkoloids, or a combination thereof.  
     
     
         22 . The method of  claim 1  wherein the one or more non-acidic compounds obtained in the selective extraction comprises less than about 5 wt. % acidic compounds.  
     
     
         23 . The method of  claim 1 , further comprising contacting the plant tissue with an acid in a third solvent, to neutralize the salt and to remove the one or more acidic compounds from the plant tissue.  
     
     
         24 . The method of  claim 23  wherein the acid comprises hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, acetic acid, formic acid, or a combination thereof.  
     
     
         25 . The method of  claim 23 , wherein the third solvent comprises an optionally substituted aromatic compound, an optionally substituted heterocyclic compound, an optionally substituted cyclic compound, an optionally substituted linear or branched compound, or combination thereof, wherein suitable substituents include (C 1 -C 6 )alkyl, hydroxyl, halo, cyano, nitro, oxo, thioxo, amino, carboxyl, or combinations thereof.  
     
     
         26 . The method of  claim 23 , wherein the third solvent comprises isopropanol, ethanol, methanol, methylene chloride, toluene, o-xylene, m-xylene, p-xylene, carbon dioxide, Xe, Freon-23, ethane, N 2 O, SF 6 , propane, ammonia, n-C 4 H 10 , (C 2 H 5 ) 2 O, or a combination thereof.  
     
     
         27 . The method of  claim 23 , wherein the third solvent comprises an additive.  
     
     
         28 . The method of  claim 27  wherein the additive is methanol; ethanol; 1-propanol; 2-propanol; 1-hexanol; 2-methoxy ethanol; tetrahydrofuran; 1,4-dioxane; acetonitrile; dichloromethane; ammonia; chloroform; propylene carbonate; N,N-dimethylacetamide; dimethyl sulfoxide; formic acid; water; carbon disulfide; acetone; propane; toluene; hexanes; pentanes; o-xylene; m-xylene; p-xylene; toluene; or a combination thereof.  
     
     
         29 . The method of  claim 1 , wherein the one or more acidic compounds comprises betulin acid, betulin-3-caffeate, tannin, phenol, caffeic acid, cichoric acid, valerenic acid, isovaleric acid, flavonoid, quercetin, kaempferol, catechin, lignin, shikimic acid, succinic acid, amino acid, nicotinic acid, pantothenic acid, anthraquinone, acidic galactan, benzoic acid, quinic acid, malic acid, citric acid, hippuric acid, phenolic acid, ferulic acid, chlorogenic acid, norsolorinic acid, fatty acids, tartaric acid, dicaffeate, cinnamic acid, or a combination thereof.  
     
     
         30 . The method of  claim 29  wherein the one or more acidic compounds obtained from the selective extraction comprises less than about 5 wt. % non-acidic compounds.  
     
     
         31 . A method for selectively extracting one or more non-acidic compounds from plant tissue in the presence of one or more acidic compounds, the method comprising: 
 (a) contacting the plant tissue with an aluminum alkoxide in a first solvent to immobilize the acidic compound as a salt on the plant tissue; and    (b) contacting the plant tissue with a second solvent suitable to remove the one or more non-acidic compounds;    thereby effectively providing a solution comprising the one or more non-acidic compounds;    wherein the one or more non-acidic compounds comprises lupeol, betulin, taxol, paclitaxel, echinacea extract, valerian root extract, ginkgolide A, ginkgolide B, ginkgolide C, bilobalide, garlic extract, ginseng extract, aloe gel, barbaloin, cranberry extract, eleutheroside A, eleutheroside B, eleutheroside C, eleutheroside D, eleutheroside E, eleutheroside G, kava extract, dill seed oil, kola extract, quinoline alkoloids, or a combination thereof; and    wherein the one or more acidic compounds comprises betulin acid, betulin-3-caffeate, tannin, phenol, caffeic acid, cichoric acid, valerenic acid, isovaleric acid, flavonoid, quercetin, kaempferol, catechin, lignin, shikimic acid, succinic acid, an amino acid, nicotinic acid, pantothenic acid, anthraquinone, acidic galactan, benzoic acid, quinic acid, malic acid, citric acid, hippuric acid, phenolic acid, ferulic acid, chlorogenic acid, norsolorinic acid, a fatty acid, tartaric acid, dicaffeate, cinnamic acid, or a combination thereof.    
     
     
         32 . The method of  claim 31 , further comprising treating the plant tissue with an acid in a third solvent to provide a solution comprising the one or more acidic compounds.  
     
     
         33 . A method for selectively extracting lupeol, betulin, or a combination thereof from birch bark in the presence of betulinic acid, betulin-3-caffeate, or a combination thereof, the method comprising: 
 (a) contacting the birch bark with an aluminum alkoxide in a first solvent comprising xylene thereby effectively immobilizing the betulinic acid, betulin-3-caffeate, or combination thereof as a salt on the birch bark; and    (b) contacting the birch bark with a second solvent suitable to remove the lupeol, betulin, or combination thereof.    
     
     
         34 . The method of  claim 33 , further comprising treating the birch bark with an acid in a third solvent to provide the betulinic acid, betulin-3-caffeate, or combination thereof.  
     
     
         35 . A composition of matter comprising the one or more non-acidic compounds as prepared in any one of claims  1 - 34 .  
     
     
         36 . A composition of matter comprising the one or more acidic compounds as prepared in any one of  claim 23 ,  32 , or  34 .  
     
     
         37 . Taxol obtained by the process of contacting a mixture of a basic component and a first solvent with  Taxus yunnanesis  bark to immobilize one or more acidic compounds on the  Taxus yunnanesis  bark and contacting the  Taxus yunnanesis  bark with a second solvent suitable to remove the taxol, to effectively provide a solution comprising taxol comprising less than about 5 wt. % of tannins, fatty acids, phenols, or a combination thereof.  
     
     
         38 . Betulin obtained by the process of contacting a mixture of a basic component and a first solvent with birch bark to immobilize one or more acidic compounds on the birch bark and contacting the birch bark with a second solvent suitable to remove the betulin, to provide a solution comprising betulin comprising less than about 5 wt. % of betulinic acid, betulin-3-caffeate, or a combination thereof.