Title of Invention	"A METHOD FOR OBTAINING A MACROLIDE"
Abstract	Provided is a method for obtaining a macrolide, especially tacrolimus, from biomatter.

Full Text

FIELD OF THE INVENTION The present invention relates to a method of extracting a macrolide, for example tacrolimus, from biomatter, especially fermentation broth. BACKGROUND OF THE INVENTION Macrolides are multi-membered lactone rings having one or more deoxy sugars as substituents. Erythromycin, azithromycin, and clarithromycin are macrolides that have bacteriostatic and / or bactericidal activity. Tacrolimus (FK 506) is also a macrolide antibiotic that is also an immunosuppressive agent More potent than cyclosporin, tacrolimus has a selective inhibitory effect on T-lymphocytes. The macrolides are typically obtained by fermentation, although synthetic routes to some are known. The present extraction method offers several advantages over the • prior art. For example, the entire fermentation broth can be used as starting material for the present method ("whole broth method") and the use of hydrophobic extraction solvent results in an efficient extraction yield, leaving behind most water-soluble impurities, with removal oTmycelium in one step. Concentration under reduced pressure at temperature above 25°C and reduced pressure results in a high evaporation rate of solvent without precipitation or decomposition of tacrolimus. Further advantages of the present invention will be apparent to the skilled artisan. The invention relates to a method for obtaining a macrolide from a macrolide-containing biomatter by extracting the macrolide with hydrophobic solvents at pH of between 5.5 and 13. As discussed in paragraph 1 above, Keri is not believed to be prior art, and Takesako is directed to production of aminoanthracene compounds, which are different chemically and structurally from macrolides. Takesako does not teach a method of obtaining a macrolide from a macrolide-containing biomatter using hydrophobic solvent at pH between 5.5 and 13. In addition, as set forth above, the claimed process is also inventive over the process described in Takesako. SUMMARY OF THE INVENTION In one aspect, the present invention relates to a method for obtaining a macrolide, especially tacrolimus, including the step of extracting macrohde-containing biomatter with a hydrophobic extraction solvent, especially wherein the hydrophobic extraction solvent is selected from the .group consisting of n-butanol, iso-butanol, C2-C6 linear and branched esters of acetic acid or formic acid, C3-C6 linear or branched aliphatic ketones, halogenated methanes, halogenated ethanes, and aromatic hydrocarbons that are liquid at 25° C and that have a boiling point at atmospheric pressure less than about 150°C, to obtain a solution of the macrolide in the hydrophobic extraction solvent, wherein the pH of the biomatter being extracted is about 5.5 to about 13. In another aspect, the present invention relates to a method for obtaining a macrolide, especially tacrolimus, including the step of extracting macrohde-containing biomatter with a hydrophobic extraction solvent, especially wherein the hydrophobic extraction solvent is selected from the group consisting of n-butanol, isro-butanol, C2-C6 linear and branched esters of acetic acid or formic acid, C3-C6 linear or branched ahphatic ketones, halogenated methanes, halogenated ethanes and aromatic hydrocarbons that are liquid at 25° C and that have a boiling point at atmospheric pressure less than about 150°C, wherein the extraction is at a temperature between about 2° C to about 70°C, especially between about 15°C and about 35°C, to obtain a solution of the macrolide in the hydrophobic extraction solvent. In a farther aspect, the present invention relates to a method for obtaining a macrolide, especially tacrolimus, including the step of extracting macrolide-containing biomatter with a hydrophobic extraction solvent, especially wherein the hydrophobic extraction solvent is selected from the group consisting of n-butanol, iso-butanol C2-C6 linear and branched esters of acetic acid or formic acid, C3-C6 linear or branched ahphatic ketones, halogenated methanes, halogenated ethanes, and aromatic hydrocarbons that are liquid at 25° C and that have a boiling point at atmospheric pressure less than about 150°C, wherein the extraction is at a temperature between about 2° C to about 70° C, especially between about 15°C and about 35°C, and at a pH of between about 5.5 and about 13, especially between about 7.5 and about 13, to obtain a solution of the macroUde in the hydrophobic extraction solvent. In a further aspect, the present invention relates to a method for obtaining a macrolide, especially tacrolimus, including the steps of extracting macrolide-containing biomatter with a hydrophobic extraction solvent, especially wherein the hydrophobic extraction solvent is selected from the group consisting of n-butanol, fro-butanol, C2-C6 linear and branched esters of acetic acid or formic acid, C3-C6 linear or branched ahphatic ketones, halogenated methanes, halogenated ethanes, and aromatic hydrocarbons that are liquid at 25° C and that have a boiling point at atmospheric pressure less than about 150°C, wherein the extraction is at a temperature between about 2° C to about 70° C, especially between about 15°C and about 35°C, and at a pH of between about 5.5 and about 13, especially between about 7.5 and about 13, to obtain a solution of the macrolide in the hydrophobic extraction solvent, concentrating the macrolide-containing solution, treating the concentrated solution by column chromatigraphy to obtain at least one macroUde-containing fraction that is a macroUde-containing solution, and crystallizing the macrolide from the solution. In yet another aspect, the present invention relates to a method for obtaining a macrolide, especially tacrolimus, including the steps of extracting macroUde-containing biomatter with a hydrophobic extraction solvent, especially wherein the hydrophobic extraction solvent is selected from the group consisting of n-butanol, iso-butanol, C2-C6 linear and branched esters of acetic acid or formic acid, C3-C6 linear or branched aliphatic ketones, halogenated methanes, halogenated ethanes, and aromatic hydrocarbons that are liquid at 25° G and that have a boiling point at atmospheric pressure less than about 150°C, to obtain a solution of the macrolide in the hydrophobic extraction solvent, separating the solution containing the macrolide from the extracted macroUde-containing biomatter, concentrating the separated macrolide-containing solution, treating the concentrated solution by column chromatography to obtain at least one macrolide-containing fraction that is a macroUde-containing solution, optionally concentrating the solution, and crystallizing the macrolide from the optionallyconcentrated separated solution by cooling, especially to a temperature of about 20°C or less, and isolating the crystallized macrolide. In yet another aspect, the present invention relates to a method for obtaining a macrolide, especially tacrolimus, including the steps of extracting macrolide-containing biomatter with a hydrophobic extraction solvent, especially wherein the hydrophobic extraction solvent is selected from the group consisting of n-butanol, isro-butanol, C2-C6 linear and branched esters of acetic acid or formic acid, C3-C6 linear or branched aliphatic ketones, halogenated methanes, halogenated ethanes, and aromatic hydrocarbons that are liquid at 25° C and that have a boiling point at atmospheric pressure less than about 150°C, to obtain a solution of the macrolide in the hydrophobic extraction solvent, separating the solution containing the macrolide from the extracted macrolide-containing biomatter, concentrating the separated macrolide-containing solution, treating the concentrated solution by column chromatography to obtain at least one macroUde- containing fraction that is a macrolide-containing solution, optionally concentrating the solution, and crystallizing the macrohde from the optionally concentrated separated solution by combining the concentrated separated solution with a crystallization solvent selected from acetonitrile, methanol, ethanol, acetone, diethyl ether, ethyl acetate, the hexanes, the heptanes, and water, and isolating the crystallized macrolide. In still a further aspect, the present invention relates to a method of obtaining a macrolide, especially tacrolimus, including the step of extracting macrolide containing biomatter obtained from a microorganism selected form Streptomyces tsukubaensis, Streptomyces hygroscopicus, and Streptomyces lividans, with a hydrophobic extraction solvent, wherein the hydrophobic extraction solvent is selected from the group consisting of n-butanol, iso-butanol, C2-C6 linear and branched esters of acetic acid or formic acid, C3-C6linear or branched aliphatic ketones, halogenated methanes, halogenated ethanes, and aromatic hydrocarbons that are liquid at 25° C and that have a boiling point at atmospheric pressure less than about 150°C5 to obtain a solution of the macrolide in the hydrophobic extraction solvent, weherein the pH of the bimatter extracted is about 5.5 to about 13. In yet another aspect, the present invention relates to a method of obtaining tacrolimus from tacrolimus-containing biomatter including the steps of: extracting tacrolimus-containing biomatter that is whole fermentation broth obtained by fermentation of a microorganism selected from the group consisting of Streptomyces tsukubaensis, Streptomyces hygroscopicus, and Streptomyces lividans, with a hydrophobic extraction solvent selected form the group consisting of n-butyl acetate, iso-butyl acetate, t-butyl acetate, ethyl acetate, propyl acetate, ethyl formate, butyl methyl ketone, dichloromethane, chloroform, tetrachloromethane, and toluene at a temperature between about 2° C and about 70°C, especially between about 15°C and about 35°C at a pH between about 5.5 and about 13, especially between about 7.5 and about 13 to obtain a solution of tacrolimus in the hydrophobic extraction solvent; separating the tacrolimus-containing solution from the extracted tacrolimus-containing biomatter; concentrating the tacrolimus-containing solution; treating the concentrated solution by column chromatography to obtain at least one macrohde-containing fraction that is a macrolide-containing solution, optionally concentrating the solution, and crystallizing the tacrolimus from the optionally concentrated separated solution by cooling it or by combining it with a crystallization solvent selected from acetonitrile, methanol, ethanol, acetone, diethyl ether, ethyl acetate, the hexanes, the heptanes, and water, whereby a precipitate of crystallized tacrolimus is formed; and separating tacrolimus. In still yet another embodiment, the present invention relates to a method of obtaining tacrolimus from tacrolimus-containing biomatter including the steps of: extracting tacrolimus-containing biomatter that is whole fermentation broth obtained by fermentation of a microorganism selected from the group consisting of Streptomyces tsukubaensis, Streptomyces hygroscopicus, and Streptomyces lividans, with a iso-butyl acetate, at a temperature between about 2° C and about 70°C, especially between about 15°C and about 35°C, to obtain a solution of tacrolimus in wo-butyl acetate solvent; separating the tacrolimus-containing iso-butyl acetate solution from the extracted tacrolimus-containmg biomatter, concentrating the tacrolimus-containing iso-butyl acetate solution; treating the concentrated solution by column chromatography to obtain at least one macrolide-containing fraction that is a macrolide-containing solution, optionally concentrating the solution, and crystallizing the tacrolimus from the optionally concentrated separated solution by cooling it to a temperature of about 20°C or less, or by combining it with a crystallization solvent selected from acetonitrile, methanol, ethanol, acetone, diethyl ether, ethyl acetate, the hexanes, the heptanes, and water, whereby a precipitate of crystallized tacrolimus is formed; and separating tacrolimus. DETAILED DESCRIPTION OF THE INVENTION In one embodiment, the present invention provides a method for obtaining a macrolide, preferably tacrolimus (also known as FK 506), from macrolide-containing biomatter that includes the step of extracting the macrolide from the macrohde-containing biomatter with a hydrophobic extraction solvent to obtain a solution of the macrolide in the hydrophobic extraction solvent, wherefrom the macrolide can be obtained. In another embodiment, the present invention provides a method for obtaining a macrolide, preferably tacrolimus, from macrolide-containing biomatter by extracting the biomatter with a hydrophobic extraction solvent to obtain a solution of the macrolide followed by concentration of the solution to obtain a concentrate, wherefrom the macrolide is isolated. Macrolide-containing biomatter is matter obtained from or through use of a macrolide-producing microorganism, for example bacteria or fungus that produces macrolide by fermentation or culturing or the like. Fermentation of microorganism can be carried out by methods well known to the skilled artisan and described, for example, in Surjit S. Sengha, Fermentation, in 10 Kirk Othmer Encyclopedia of Chemical Technology. 361 (Jacquiline I. Kroschwitz, ed. 4th ed. 1993). Preferred macrohde-containing biomatter is tacrolimus-containine biomatter, particularly fermentation broth obtainable by fermentation using a tacrolimus-producing microorganism, for example, Streptomyces tstikubaensis, new and mutated strains thereof, Streptomyces hygroscopicus, and Streptomyces lividans, as described in United States Patent numbers 4,894,366,5,116,756,5,624,842, 5,496,727, and 5,622,866. Mycelium and filtrate obtained by filtration of fermentation broth from fermentation of a macrolide-producing microorganism are also biomatter useful in the practice of the present invention. The entire fermentation broth, i.e. "whole broth" from fermentation of a macrolide-producing microorganism, unfiltered or purified to separate mycelium, is a preferred macrolide-containing biomatter for the practice of the present invention. When whole broth is used, the present method can be referred to as a "whole-broth method". The macrolide-containing biomatter is extracted with a hydrophobic extraction solvent that is a solvent for the macrolide, especially tacrolimus, but that is only sparingly soluble in water at 25°C. Preferred hydrophobic extraction solvents are C2 - C6 linear and branched esters of acetic acid or formic acid, for example iso-butyl acetate, C3 - C6 linear or branched aliphatic ketones, halogenated methanes, for example dichloromethane, halogenated ethanes, for example dichloroethane, and aromatic hydrocarbons that are liquid at 25°C and that have a boiling point at atmospheric pressure less that about 150°C. Normal and iso-butyl alcohols can also be used as the hydrophobic extraction solvent. Preferred as hydrophobic extraction solvents are iso-butyl acetate, n-butyl acetate, t-butyl acetate, ethyl acetate, propyl acetate, ethyl formate, butyl methyl ketone (2-hexanone), dichloromethane, chloroform, tetrachloromethane, and toluene. Ethyl acetate and iso-butyl acetate are particularly preferred hydrophobic extraction solvents. The extraction to form a solution of the macrolide can be performed using such methods and equipment as are known to skilled artisan and routiner alike. The method and equipment chosen must only provide adequate agitation and allow for separation of the solution from extracted macrolide-containing biomatter, or for transfer of the extraction mixture to a separation device. Extraction can be carried out at any convenient temperature between about 2°C and about 70° C. Preferably, the extraction is carried out at a temperature between about 15° C and about 35°C. The skilled artisan will know to optimize the extraction time depending on the macrolide-containing biomatter, hydrophobic extraction solvent, equipment, and temperatures used. At the end of the extraction, the extraction mixture includes a solution of the macrolide in the hydrophobic extraction solvent as well as residual extracted macrolide-containing biomatter. in a preferred embodiment, the extraction is performed on biomatter, for example fermentation broth, that is not first subjected to any purification treatment, for example filtration that would remove mycelium. In this case, the extraction is referred to as whole broth extraction. The extraction can be performed at any pH between about 1 and about 13. Preferably, the extraction is conducted at apH between about 5.5 and about 13, most preferably between about 7.5 and about 13. The pH of the biomatter, especially fermentation broth, can be adjusted using a suitable inorganic base, for example NH4OH, NaOH, KOH, LiOH, or Ca(OH)2, to mention just a few. The present inventors have observed particular advantages, especially in regards to the purity of macrolide, when the extraction is carried-out on biomatter having a pH between about 5.5 and about 13. Preferably, the pH is an alkaline pH, especially a pH between about 7.5 and about 13. Following extraction, the solution of macrolide in hydrophobic extraction solvent is separated from the extraction mixture and, in preferred embodiments, concentrated to obtain a concentrate. The separation can be accomplished using methods and equipment well known to skilled artisan and routiner alike, for example decanting, separating in a separatory funnel, and centrifuging using a liquid - liquid centrifuge. The macrolide-containing solution separated from extracted macroh'de-containing biomatter is concentrated to obtain a concentrate. The concentration can be at prevailing atmospheric pressure (which the skilled artisan recognizes varies slightly about a mean of 760mm Hg), or it can be at reduced pressure, attained with the aid of, for example, a vacuum pump or water aspirator. The concentration is preferably carried out at a temperature above about 25°C. The concentration is carried out until the volume of the macrolide-containing solution is reduced to about 0,2 to about 2,0 percent of its initial volume, or less to provide concentrated macrolide-containing solutions ("concentrate"). Crude tacrolimus can be isolated from the concentrate. In preferred embodiments, the concentrate is treated by column chromatography on a silica gel column. The chromatography method applied can be that described in United States patent 4,894,366, incorporated herein in its entirety by reference. For treatment, concentrate (concentrated macrolide-containing solution) is loaded onto a silica gel column. For loading, the concentrate can be combined with a solvent that is a solvent for the macrolide, for example ethyl acetate, and slurried with silica gel. Solvent is removed from the slurry to afford silica gel loaded with macrolide and other substances from the concentrate. The loaded silica gel is charged to the top of the column and, if desired, a loading eluent is passed through the column. The column is then eluted with an eluent. The eluent can be isochratic, that is of constant composition, or the composition of the eluent can be varied during elution. Preferred eluents include mixtures of ethyl acetate and hexane. Fractions are collected to obtain at least one macrolide-containing fraction that is a solution of macrolide in eluent. Multiple macrolide-containing fractions can be combined to a sinfle macrolide-containing fraction. The macrolide-containing fraction(s) can be concentrated to obtain a concentrated solution (concentrated fraction) of macrolide, wherefrom the macrolide can be crystallized. The macrolide is crystallized (precipitated) from the preferably concentrated macrohde-containing solution. Macrolide so crystallized (precipitated) can be isolated by, for example, filtration or centrifugation. Crystallization can be effected by cooling the macrolide-containing solution, preferably to temperature of about 20°C or less. Crystallization can also be effected with the aid of a crystallization solvent that is combined with the preferably concentrated macrolide-containing solution. In preferred embodiments, the combination is thereafter maintained for a holding period of about 10 to about 60 hours at a temperature of about 25°C or below. The typical hold time is 48 hours. Useful crystallization solvents include acetonitrile, methanol, ethanol, acetone, diethyl ether, ethyl acetate, hexanes, heptanes, and water. In particular embodiments, the macrolide-containing solution is concentrated to dryness and the macrolide is obtained without further cooling and without use of a crystallization solvent. The practice of the invention is further illustrated with the following non-limiting examples. Example 1 Fermentation broth (50 ml) was mixed with 50 ml iso-butyl acetate. The pH of the mixture was adjusted to pH 2 with diluted sulfuric acid solution. After 30 minutes stirring, phases were separated. The separated iso-butyl acetate phase (39 ml) was concentrated to dryness under reduced pressure at 60 °C. The achieved yield was 83 %. Example 2 Fermentation broth (50 ml) was mixed with 50 ml iso-butyl acetate. Magnesium sulfate of 250 mg and some drops of diluted dodecyl trimethyl ammonium chloride solution were added to the mixture. The pH of the mixture was adjusted to pH 4 with diluted sulfuric acid solution. After 30 minutes stirring, phases were separated. The separated iso-butyl acetate phase (44 ml) was concentrated to dryness under reduced pressure at 70 °C. The achieved yield was 88 %. Example 3 Fermentation broth (50 ml) was mixed with 50 ml iso-butyl acetate. Magnesium sulfate of 250 mg and some drops of diluted dodecyl trimethyl ammonium chloride solution were added to the mixture. The pH of the mixture was adjusted to pH 8 with diluted sodium hydroxide solution. The combination was heated to 35-40 °C. Phases were separated after 30 minutes stirring. The iso-butyl acetate phase (44 ml) was concentrated to dryness under reduced pressure at 82 °C. The achieved yield was 94 %. Example 4 Fermentation broth (50 ml) was mixed with 50 ml iso-butyl acetate. Magnesium sulfate of 250 mg and some drops of diluted dodecyl trimethyl ammonium chloride solution were added to the mixture. The pH of the mixture was adjusted to pH 10 with diluted sodium hydroxide solution. The combination was cooled to 15 °C. Phases were separated after 30 minutes stirring. The iso-butyl acetate phase (43 ml) was concentrated to dryness under reduced pressure at 55 °C. The achieved yield was 92 %. Example 5 Fermentation broth (50 ml) was mixed with 50 ml ethyl acetate. Magnesium sulfate of 250 mg and some drops of diluted dodecyl trimethyl ammonium chloride solution were added to the mixture. The pH of the mixture was adjusted to pH 4 with diluted sulfuric acid solution. Phases were separated after 30 minutes stirring. The separated ethyl acetate phase was concentrated to dryness under reduced pressure at 29 °C. The achieved yield was 92 %. We claim: 1. A method for obtaining a macrolide as hereindescribed comprising the step of extracting macrolide-containing biomatter as hereindescribed with a hydrophobic extraction solvent as hereindescribed to obtain a solution of the macrolide in the hydrophobic extraction solvent, wherein the pH of the macrolide-containing biomatter being extracted is between 5.5 and 13. 2. The method as claimed in claim 1 wherein the hydrophobic extraction solvent is selected from the group consisting of n-butanol, iso-butanol, C2-C6 linear and branched esters of acetic acid or formic acid, C3-C6 linear or branched aliphatic ketones, halogenated methanes, halogenated ethanes, and aromatic hydrocarbons that are liquid at 25° C and that have a boiling point at atmospheric pressure less than 150°C. 3. The method as claimed in claim 2 wherein the hydrophobic extraction solvent is selected from the group consisting of n-butanol, iso-butanol, n-butyl acetate, iso-butyl acetate, f-butyl acetate, ethyl acetate, propyl acetate, ethyl formate, acetone, butyl methyl ketone, methyl iso-butyl ketone, dichloromethane, chloroform, tetrachloromethane, dichloroethane, and toluene. 4. The method as claimed in claim 3 wherein the hydrophobic extraction solvent is ethyl acetate, iso-butyl acetate. 5. The method as claimed in claim 4 wherein the hydrophobic extraction solvent is iso-butyl acetate. 6. The method as claimed in claim 1 wherein the extraction is at a temperature between 2°C and 70° C. 7. The method as claimed in claim 6 wherein the extraction is at a temperature between 15°C and 35° C. 8. The method as claimed in claim 1 wherein the pH of the biomatter extracted is between 7.5 and 13. 9. The method as claimed in claim 1 wherein the macrolide-containing biomatter is obtained from a microorganism selected from Streptomyces tsukubaensis, Streptomyces hygroscopicus, and Streptomyces lividans. 10. The method as claimed in claim 9 wherein the macrolide-containing biomatter is whole fermentation broth. 11. The method as claimed in claim 10 wherein the macrolide is tacrolimus. 12. The method as claimed in claim 11 wherein the pH of the biomatter is between 7.5 and 13. 13. The method as claimed in claim 12 wherein the hydrophobic extraction solvent is iso-butyl acetate . 14. The method as claimed in claim 1 comprising the steps of, after extraction; separating the solution containing the macrolide from the extracted macrolide-containing biomatter to obtain a separated macrolide-containing solution, concentrating the separated macrolide-containing solution to form a concentrated macrolide-containing solution, loading the concentrated macrolide-containing solution onto a silica gel column and eluting with an eluent to obtain at least one macrolide-containing fraction that is a macrolide-containing solution, crystallizing the macrolide from the macrolide-containing solution , and isolating the crystallized macrolide. 15. The method as claimed in claim 14 wherein the crystallizing is effected by concentrating at least one macrolide-containing fraction that is a macrolide-containing solution and cooling the concentrated solution to a temperature of 25° C or less. 16. The method as claimed in claim 14 wherein the crystallization is effected by combining the separated solution with a crystallization solvent. 17. The method as claimed in claim 16 wherein the crystallization solvent is selected from the group consisting of acetonitrile, methanol, ethanol, i-propanol, acetone, diethyl ether, ethyl acetate, the hexanes, the heptanes, and water. 18. The method as claimed in claim 17 wherein the crystallization solvent is selected from the group consisting of methanol, ethanol, i-propanol, and water. 19. The method as claimed in claim 16 wherein the combination of separated solution and crystallization solvent is maintained at a temperature of 25°C or less for a holding period of between 10 and 60 hours. 20. A method of obtaining tacrolimus as claimed in claim 1 from tacrolimus-containing biomatter comprising the steps of: a) extracting tacrolimus-containing biomatter that is whole fermentation broth obtained by fermentation of a microorganism selected from the group consisting of Streptomyces tsukubaensis, Streptomyces hygroscopicus, and Streptomyces lividans with a hydrophobic extraction solvent selected form the group consisting of n-butanol, iso-butanol, n-butyl acetate, iso-butyl acetate, t-butyl acetate, ethyl acetate, propyl acetate, ethyl formate, butyl methyl ketone, dichloromethane, chloroform, tetrachloromethane, dichloroethane and toluene to obtain a solution of tacrolimus in hydrophobic extraction solvent at a temperature between 2° C and 70°C and a pH between 5.5 and 13, b) separating the tacrolimus-containing solution from the extracted tacrolimus-containing biomatter, c) concentrating the tacrolimus-containing solution, d) loading the concentrated tacrolimus-containing solution onto a silica gel chromatography column and eluting the column with an eluent to obtain at least one tacrolimus-containing fraction that is a tacrolimus-containing solution, d) crystallizing the tacrolimus from at least one tacrolimus- containing fraction whereby a precipitate of crystallized tacrolimus is formed, and e) separating crystallized tacrolimus. 21. The method as claimed in claim 20 wherein the pH of the whole fermentation broth is between 7.5 and 13. 22. The method as claimed in- claim 20 wherein the hydrophobic extraction solvent is iso-butyl acetate. 23. The method as claimed in claim 20 wherein the extraction is at a temperature between 15° C and 30° C. 24. The method as claimed in clam 20 wherein the crystallization is effected by concentrating the at least one tacrolimus-containing fraction and cooling the concentrated fraction to a temperature of 25°C or less. 25. The method as claimed in claim 20 wherein the crystallization is effected by combining the at least one tacrolimus-containing fraction with a crystallization solvent selected from the group consisting of acetonitrile, methanol, ethanol, acetone, diethyl ether, ethyl acetate, the hexanes, the heptanes, and water. 26. A method for obtaining tacrolimus from tacrolimus-containing biomatter, as claimed in claim 20 the step of extracting tacrolimus-containing biomatter that is whole fermentation broth with a hydrophobic extraction solvent selected from the group consisting of n-butyl acetate, iso-butyl acetate, t-butyl acetate, ethyl acetate, propyl acetate, ethyl formate, butyl methyl ketone, dichloromethane, chloroform, tetrachlorome thane, and toluene, wherein the pH of the tacrolimus-containing biomatter is between 5.5 and 13.

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2330-delnp-2004-abstract.pdf

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