BG67337B1 - Method for preparation of purified galantamine hydrobromide - Google Patents

Abstract

The invention relates to a method for preparation of purified galantamine hydrobromide, in particular to extraction of galantamine from plant raw material, its conversion into hydrobromide and its purification. It involves alkaline extraction of Amaryllidaceae, in particular Narcissus and Leucojum, conversion of galantamine base to galantamine hydrobromide and purification of the resulting salt to obtain galantamine hydrobromide with an HPLC grade more than 99 % and high yield of about 90 - 92 % of the content of galantamine hydrobromide in the technical product.

Description

Field of technology

The invention relates to a process for the preparation of purified galantamine hydrobromide, in particular to the extraction of galantamine from a plant material, its conversion into hydrobromide and its purification.

BACKGROUND OF THE INVENTION

Galantamine- (4aS, 6R, 8aS) -4a, 5, 9, 10, 11.12-hexahydro-3-methoxy-11-methyl-6H-benzofuro [3a, 3,2-e] [2] benzazepin-6-ol ; galanthamine, lycoremin, with the following structural formula:

BG 67337 Bl sn

U> fl ₃ CO _ ^: is a selective acetylcholinesterase inhibitor. The first information about its isolation dates back to 1952. The sources of galantamine are: Amaryllidaceae, Caucasian snowdrops, Galanthus woronowii Vel., Galanthus Nivalis, G. narcissus, G. leucojum, G. orinium, Narcissus iv. Salome, Narcissus pseudonarcissus, Narcissus leonensis, Narcissus nivalis, Galanthus elwesil. Galantamine hydrobromide, alone or in combination, is part of a variety of drugs.

Isolation of galantamine from Amaryllidaceae is known by extraction of plant material pre-alkalized with ammonia, with dichloromethane or another chlorinated hydrocarbon. After treatment of the obtained extract with dilute sulfuric acid, precipitation with aqueous ammonia follows. The galantamine remaining in the solution was extracted with diethyl acetate or dichloromethane and then purified (1).

Extraction with dichloroethane or Narcissus Carlton gasoline premixed with powdered sodium carbonate has been described. The resulting extract was evaporated to dryness, the residue was dissolved in dilute sulfuric acid, extracted with ether, the remaining aqueous solution was basified to pH 9 and extracted with diethyl ether, concentrated to dryness, propanol was added until galantamine crystallized (2). . The toxic solvents used in large volumes are a disadvantage of the method.

A method for isolating galantamine from biological material (Amaryllidaceue, such as narcissi and crinum, in particular from narcissus pseudonarcissus Carlton and Crinum amabile) by extraction with a toxic safe solvent (diethyl ether or special boiling point gas, which is preferred) is disclosed. and subsequent purification by liquid-liquid extraction, which in the first step is carried out at a pH of about 4 and in the second at a pH of about 9. Prior to extraction, the biological material is mixed with an alkaline powder (sodium carbonate). The resulting galantamine was recrystallized from a suitable solvent (isopropanol) to a purity of 99% (3).

A semi-synthetic method for the preparation of galantamine and its derivatives is protected. As a raw material, yellow daffodil or snowdrop bulbs are used, which are mixed with a secondary amine of the formula given in the description, in aqueous phosphate buffer and ethanol. The resulting mixture was extracted with ethyl acetate and concentrated (4).

BG 67337 Bl

A method for extracting pure galantamine by extraction of Amaryllidaceae with an aqueous solution of inorganic or organic acids has been proposed. The resulting extract was applied to an adsorbent, followed by washing with water and eluting with a water-miscible solvent and then concentrating the combined fractions. The resulting alkaloid concentrate is adsorbed onto a cation exchange polymer and eluted with an aqueous inorganic base solution. Concentration followed again, but re-eluted with a water-immiscible solvent. The newly obtained concentrate is subjected to chromatographic purification on alumina using a water-immiscible solvent as the mobile phase. The resulting galantamine is crystallized from a suitable solvent and then recrystallized from methyl isobutyl ketone or from tert-butyl methyl ether. Other variants of purification-passage through salt are provided, etc. The declared purity of the obtained galantamine is over 90%, mostly 99% (5). However, the method is quite complicated by many operations, the need for specialized equipment, etc.

The use of centrifugal chromatography (liquid chromatography without solid support) for the purification of galantamine is protected. In Example 1 Leucojum aestivum leaves moistened with ammonia (10%) in water were used to prepare galantamine, the resulting mixture was treated with ethyl acetate for 18 hours, after leaching the ethyl acetate the resulting solution was extracted repeatedly with aqueous solution (3 %) of sulfuric acid, after alkalizing the aqueous phase with ammonium hydroxide, several extractions with chloroform are performed, the subsequent operations lead to the production of total alkaloids, which are subsequently subjected to separation and purification by the proposed (in different embodiments) chromatographic method - many operations requiring a long time, large amounts of solvents and specialized chromatographic equipment are used (6).

A method for isolating galantamine from biological material is described, comprising acid extraction followed by elution with a water-miscible organic solvent of the absorbed organic compounds, washing with water and concentration of the alkaloids. The biological material is Amaryllidaceae: Galanthus, Narcissus, Leucojum and / or Lycoris (7).

Protection of galantamine-rich hippeastrum papilio extract obtained by acidic (2% sulfuric acid) extraction of the saturated plant source, followed by alkalization with ammonia and extraction with chloroform, was requested. After several purification operations, a mixture of alkaloids is obtained, the composition of which is determined by gas chromatography (8).

A method is known for the preparation of glantamine derivatives by reacting Galantamine base with BOC-Gly-OCH2CN (tert-butyloxy carbonyl glycine cyanmethyl ester in the presence of a DBU condensing agent in an organic solvent medium (CH2Cl, DMF, CHCl3, EtOAc) followed by , alkalizing and extracting the aqueous acid phase and re-extracting to isolate the 6-O- (BOC-glycyl) -galantamine ester, unblocking the resulting Gal with a BOC protecting group with an acid, condensing the resulting ester by di-; acids (which are optionally substituted with a condensing agent) in an organic solvent medium (CH2Cl, DMF, CHCl3, EtOAc) and the presence of an alkalizing agent to give crude galantamine derivatives which undergo crystallization (9).

Protected is a method for purification of galanthamine hydrobromide extracted from Amaryllidaceae: Galanthus, Narcissus, Crinum, Leucojum.

The preparation of galantamine used in the protected method is illustrated in Example 1, in which ground bulbs of Narcissus Pseudonarcissus Carlton containing 0.3% galantamine were mixed with 10% aqueous sodium carbonate solution and extracted seven times with toluene at 65-70 ° C.

BG 67337 B1 was concentrated and treated with 2% sulfuric acid, the resulting aqueous phase was basified with ammonium hydroxide to pH 9 and extracted four times with toluene, after evaporation to dryness in vacuo to give total alkaloids containing 40% galanthamine. Examples 2 and 3 illustrate the preparation of the hydrobromide, 88% and 85% pure, by reacting the alkaloids obtained from Example 1 with 48% hydrobromic acid in ethanolic and isopropanol media, respectively. The resulting hydrobromide was suspended in water, diluted with 10% sodium carbonate and extracted five times or seven times with tert-butyl acetate. The resulting organic phase was washed, concentrated in vacuo and allowed to crystallize, the resulting galantamine hydrobromide crystals were filtered and dried at 50 ° C or 70 ° C and had HPLC purity above 99% and impurities below 0.1%. The method in different stages uses large amounts of solvents, involves repeated operations (10).

It is clear from the above that the issue of extracting galantamine from plants and obtaining its hydrobromide with pharmacopoeial purity has not lost its relevance. Due to the wide and varied application of this alkaloid, there is a need for a simple, easily feasible method to ensure good yields of a pharmacopoeial product.

SUMMARY OF THE INVENTION

Unexpectedly, it has been found that galantamine hydrobromide of pharmacopoeial purity can be obtained by:

(a) extracted from Leucojum aestivum L or Narcissus Carlon cv in an aqueous medium or in a lower alcohol medium, alkalized with calcium hydroxide to pH 9-12 and a temperature of 30-40 ° C, galantamine base is filtered and concentrated.

b) is extracted 2 to 4 times with methyl isobutyl ketone, ethyl acetate, butyl acetate or n, butanol in an extract / extractant ratio of 8: 1 for extractions in aqueous medium and respectively 2: 1 for extractions in the presence of lower alcohol;

(c) after concentrating the combined organic extracts from 1/20 to 1/30 of the initial volume, the solvent is replaced by ethanol and the resulting galantamine base by treatment with hydrobromic acid to galanthamine hydrobromide;

d) purification of the galantamine hydrobromide obtained from step c) with a purity of 80-86%, at a temperature of 80-85 ° C in an aqueous medium is purified with activated carbon, after filtration the purified solution is cooled to 20-25 ° C and basified with ammonium hydroxide to pH 9-12;

e) the resulting galantamine base is extracted 2-4 times with methyl isobutyl ketone, ethyl acetate or butyl acetate in an alkaline aqueous solution / organic solvent ratio of 2: 1 to 3: 1; concentrate from 1/5 to 1/10 of the original volume and cool;

(f) treated with a selective reagent for N-desmethylgalanthamine, in particular di-tert-butyl dicarbonate or diethyl pyrocarbonate in a molar excess of 1,12-1,2 relative to the content of N-desmethylgalantamine (determined by HPLC) in the alkaloid mixture with stirring 7-10 hours, followed by extraction with mineral acid to pH 2-3 in aqueous medium, alkalization of the acidic aqueous extract of galanthamine salt at pH 9-12;

g) followed by extraction of the released galantamine base with methyl isobutyl ketone, ethyl acetate or butyl acetate at an aqueous / organic solvent ratio of 2: 1 to 3: 1, change of the solvent with ethanol and treatment with hydrochloric acid to obtain galantamine hydrobromide with HPLC purity of more than 99%.

BG 67337 Bl

An advantage of the process according to the invention is that Galantamine hydrobromide is elegantly obtained with a pharmacopoeial purity of 99.9% and a high yield in the range of 90-92% of the Galantamine hydrobromide content in the technical product.

The following examples illustrate the essence of the method according to the invention without limiting it.

An embodiment of the invention

Preparation of Galantamine hydrobromide (80-86% purity)

Example 1:

A) 500 kg of chopped Narcissus Carlon cv bulbs with a galantamine content of 0.09% are extracted four times with 1500 l of aqueous calcium hydroxide solution at a temperature of 30 ° C and pH 9. The resulting aqueous-alkaline extracts after filtering off the excess calcium hydroxide was extracted four times with 200 l of butyl acetate each time. The resulting butyl acetate extracts containing the alkaloid mixture were combined and concentrated in vacuo to a volume of 20 liters, 50 196% ethanol was added, and the resulting mixture was concentrated at atmospheric pressure to a volume of 6 1. The resulting Galantamine base alcohol solution was cooled to 5-10 ° C and treated at this temperature with 48% hydrobromic acid until a stable pH value of the solution of 2.0-3.0 was reached. The resulting suspension of Galantamine hydrobromide was allowed to crystallize under constant stirring at 0 -5 ° C for 12 hours, then filtered and dried at 40 ° C. 0.53 kg of Galantamine hydrobromide with an HPLC purity of 83% is obtained.

B) Work analogously to the method described in Example 1A), except that the resulting aqueous-alkaline extracts, after filtering off the excess calcium hydroxide, are extracted four times with 200 l of n-butanol instead of butyl acetate. 0.56 kg of galanthamine hydrobromide with an HPLC purity of 84% are obtained.

C) Work analogously to the method described in Example 1A), except that the resulting aqueous-alkaline extracts, after filtering off the excess calcium hydroxide, are extracted four times with 200 l of methyl isobutyl ketone instead of butyl acetate. 0.54 kg of Galantamine hydrobromide with an HPLC purity of 84% is obtained.

D) 500 kg of chopped Narcissus Carlon cv bulbs were extracted six times with 1500 l of aqueous calcium hydroxide solution at a temperature of 40 ° C and at pH 10. Follow the procedure described in Example 1A). 1.0 kg of galantamine hydrobromide is obtained with an HPLC purity of 80%.

E) 500 kg of chopped Narcissus Carlon cv bulbs with a galantamine content of 0.09% are extracted three times with 1500 1 75% ethanol, alkalized with saturated calcium hydroxide solution, at a temperature of 40 ° C and pH 10. The resulting ethanol extracts were combined, the excess calcium hydroxide was filtered off and concentrated in vacuo to a volume of 200 L. The resulting aqueous concentrate was extracted three times with 100 L of butyl acetate and the resulting organic extracts containing the alkaloid mixture were combined and concentrated under vacuum volume of 20 L, 50 l of 96% ethanol are added, the mixture thus obtained is concentrated at atmospheric pressure to a volume of 6 L. The resulting galantamine base alcohol solution is further treated as described in Example 1 A).

0.56 kg of Galantamine hydrobromide with an HPLC purity of 86% are obtained.

E) Follow the procedure described in Example 1E) with the difference that the combined ethanol extracts after filtration of the excess calcium hydroxide are extracted with n-butanol instead of butyl acetate. 0.53 kg of Galantamine hydrobromide is obtained with an HPLC purity of 86%.

BG 67337 Bl

G) Follow the procedure described in Example 1 E) with the difference that the combined ethanol extracts after filtration of the excess calcium hydroxide are extracted with methyl isobutyl ketone instead of butyl acetate. 0.51 kg of Galantamine hydrobromide is obtained with an HPLC purity of 86%.

3) 500 kg of chopped Narcissus Carlon cv bulbs with a galantamine content of 0.09% are extracted four times with 1500 1 65% ethanol, alkalized with saturated calcium hydroxide solution, at a temperature of 40 ° C and at pH 9 The procedure described in Example 1E) was followed. 0.46 kg of galantamine hydrobromide with 85% purity HPLC are obtained.

I) 500 kg of chopped Narcissus Carlon cv bulbs with a galantamine content of 0,09% are extracted six times with 1500 l of methanol of 70%, alkalized with saturated calcium hydroxide solution, at a temperature of 40 ° C and at pH 9. The resulting methanol extracts were combined, the excess calcium hydroxide was filtered off and concentrated in vacuo to a volume of 200 L. The resulting aqueous concentrate was extracted three times with 100 L of butyl acetate, the resulting organic extracts containing the alkaloid mixture were combined and concentrated volume of 20 L, 50 l of 96% ethanol are added, the mixture thus obtained is concentrated at atmospheric pressure to a volume of 6 L. The resulting galantamine base alcohol solution is further treated as described in Example 1 A). 0.54 kg of Galantamine hydrobromide with an HPLC purity of 83% is obtained.

J) Work analogously to the method described in Example 1I) except that the extraction is threefold, the combined methanol extracts after filtration of the calcium hydroxide and concentration are extracted with methyl isobutyl ketone instead of ethanol. 0.53 kg of Galantamine hydrobromide with an HPLC purity of 83% is obtained.

K) Work analogously to the method described in Example 1 I) with the difference that the combined methanol extracts after filtration of the calcium hydroxide and concentration are extracted with N. butanol instead of ethanol. 0.54 kg of Galantamine hydrobromide with an HPLC purity of 83% is obtained.

Example 2:

A) 1080 kg of dry aboveground part of Snowdrop (Leucojum aestivum L) with Galantamine content of 0.12% are extracted three times with 3500 l of ethanol of 70%, alkalized with saturated calcium hydroxide solution, at a temperature of 30 ° C and pH 10. The resulting ethanol extracts after combination, filtration and concentration were extracted three times with 100 L of butyl acetate each time. The organic extracts containing the alkaloid mixture were combined and concentrated in vacuo to a volume of 20 L, 50 L of 96% ethanol was added, and the resulting mixture was concentrated at atmospheric pressure to a volume of 10 L. 5-10 ° C and treated at this temperature with 48% hydrobromic acid until a stable pH of the solution reached 3.0. The resulting suspension of Galantamine hydrobromide was allowed to crystallize under constant stirring at 0 -5 ° C for 12 hours, then filtered and dried at 40 ° C. 1.57 kg of galanthamine hydrobromide are obtained with an HPLC purity of 85%.

B) The procedure is analogous to that of Example 2 A) with the only difference that n-butanol is used instead of butyl acetate for the extraction of the combined, filtered and concentrated ethanol extracts. 1.55 kg of Galantamine hydrobromide are obtained with an HPLC purity of 80%.

C) Work analogously to the procedure of Example 2 A) with the only difference that methyl isobutyl ketone instead of butyl acetate is used for the extraction of the combined, filtered and concentrated ethanol extracts. 1.54 kg of galanthamine hydrobromide with an HPLC purity of 80% are obtained.

BG 67337 Bl

(D) 1000 kg of dry, ground aboveground porridge of Leucojum aestivum L with a galantamine content of 0.11% are extracted four times with 3000 l of aqueous calcium hydroxide solution at a temperature of 30 ° C and at pH 9. aqueous-alkaline extracts were filtered off the excess calcium hydroxide and extracted four times with 200 l of butyl acetate each time. The resulting butyl acetate containing the alkaloid mixture was combined and concentrated in vacuo to a volume of 20 L, 50 L of 96% ethanol was added, and the resulting mixture was concentrated at atmospheric pressure to a volume of 6 L. 5-10 ° C and treated at this temperature with 48% hydrobromic acid until a stable pH of the solution reached 3.0. The resulting suspension of Galantamine hydrobromide was allowed to crystallize under constant stirring at 0 -5 ° C for 12 hours, then filtered and dried at 40 ° C. 1.2 kg of Galantamine hydrobromide with an HPLC purity of 81% are obtained.

E) The procedure of Example 2 D) was followed by extracting the obtained aqueous-alkaline extracts after filtration of the excess calcium hydroxide with n-butanol in place of the butyl acetate. 1.2 kg of galanthamine hydrobromide with an HPLC purity of 80% are obtained.

E) The procedure of Example 2 D) was followed by extracting the obtained aqueous-alkaline extracts after filtering off the excess calcium hydroxide with methyl isobutyl ketone in place of the butyl acetate. 1.2 kg of galanthamine hydrobromide with an HPLC purity of 80% are obtained.

The resulting galantamine hydrobromide, regardless of the raw material or preparation method mentioned above, is subjected to purification, including treatment with a selective reagent for N-desmethylgalantamine, illustrated below with the following non-limiting examples:

Example 3:

Preparation of Galantamine hydrobromide with HPLC purity of more than 99%

A) By treatment with BOC anhydride (Di-tert-butyl dicarbonate)

(Aa) Using methyl isobutyl ketone.

kg Galantamine hydrobromide with HPLC purity of 83% was dissolved in 200 l of purified water at a temperature of 80-85 ° C and treated with 500 g of activated carbon for 20 minutes at this temperature, followed by filtration. The resulting aqueous solution of Galantamine hydrobromide was cooled to 20-25 ° C, basified with 25% ammonium hydroxide to pH 9 and extracted three times with 100 l of methyl isobutyl ketone. The combined organic extracts contained Galantamine base concentrated to a volume of 80 L and cooled to 20-25 ° C. The thus obtained solution of Galantamine base in methyl isobutyl ketone was treated with 1.49 kg of BOC anhydride (Di-tert-butyl dicarbonate) with constant stirring for eight hours, followed by the addition of 100 l of purified water and acidification of the two-phase system by 36%. hydrochloric acid to a pH of the aqueous layer of 2.0 with constant stirring. The organic layer was removed and the acidic aqueous solution containing Galantamine hydrochloride was basified with 25% ammonium hydroxide to pH 9, then extracted three times with 100 l of methyl isobutyl ketone. The combined alkaline organic extracts containing purified Galantharamine base, vacuum to dryness, 80 1 96% ethanol was added, the resulting Galantamine base alcohol solution was cooled to 10 ° C and treated at this temperature with 48% hydrobromic acid until a stable pH of the solution reached 3.0. The resulting suspension of purified Galantamine hydrobromide was allowed to crystallize with constant stirring at 5 ° C for 12 hours, then filtered and dried at 40 ° C.

15.0 kg of Galantamine hydrobromide with an HPLC purity of more than 99% are obtained.

Ab) using ethyl acetate.

BG 67337 Bl

Work as described in Example 3aa) by replacing the methyl isobutyl ketone with ethyl acetate. 15.2 kg of Galantamine hydrobromide with an HPLC purity of more than 99% are obtained.

Ab) using butyl acetate.

Work as described in Example 3aa) by replacing the methyl isobutyl ketone with butyl acetate. 15.0 kg of galanthamine hydrobromide are obtained with an HPLC purity of over 99%.

B) Preparation of Galantamine hydrobromide with HPLC purity of more than 99% by treatment with Diethyl pyrocarbonate.

Ba) Using methyl isobutyl ketone.

kg Galant. min hydrobromide with HPLC purity of 83% was dissolved in 200 l of purified water at a temperature of 80-85 ° C and treated with 500 g of activated carbon for 20 min at this temperature, followed by filtration. The resulting aqueous solution of Galantamine hydrobromide was cooled to 20-25 ° C, basified with 25% ammonium hydroxide to pH 9 and extracted three times with 100 l of methyl isobutyl ketone. The combined organic extracts containing Galantamine base concentrate to a volume of 80 L and cool to 20-25 ° C. The thus obtained solution of Galantamine base in methyl isobutyl ketone was treated with 1.1 kg of diethyl pyrocarbonate with constant stirring for eight hours, followed by the addition of 100 l of purified water and acidification of the biphasic system with 36% hydrochloric acid to a pH of 2.0. with constant stirring. The organic layer was removed and the acidic aqueous solution containing Galantamine hydrochloride was basified with 25% ammonium hydroxide to pH 9, then extracted three times with 100 l of methyl isobutyl ketone each time. The combined alkaline organic extracts containing purified Galantamine base were concentrated in vacuo to dryness, 80 1 96% ethanol was added, the resulting Galantamine base alcohol solution was cooled to 10 ° C and treated at this temperature with 48% hydrobromic acid until at a constant pH value of the solution of 3,0. The resulting suspension of purified Galantamine hydrobromide was allowed to crystallize under constant stirring at 5 ° C for 12 hours, then filtered and dried at 40 ° C. 15.4 kg of Galantamine hydrobromide with an HPLC purity of more than 99% are obtained.

BB) using ethyl acetate.

Work as described in Example 3Ba) by replacing the methyl isobutyl ketone with ethyl acetate. 15.2 kg of Galantamine hydrobromide with an HPLC purity of more than 99% are obtained.

(Bc) using butyl acetate.

Work as described in Example 3Ba) by replacing methyl isobutyl ketone with butyl acetate. 15.2 kg of Galantamine hydrobromide with an HPLC purity of more than 99% are obtained.

Claims (1)

Process for the preparation of purified galantamine hydrobromide by alkaline extraction of Amaryllidaceae, in particular Narcissus and Leucojum, conversion of galantamine base to galantamine hydrobromide by treatment with hydrobromic acid and purification of the resulting salt, characterized in that : (a) filtering and concentrating the leucojum aestivum L or Narcissus Carlon cv extracted in an aqueous medium or in a lower alcohol medium, alkalized with calcium hydroxide to pH 9-12 at a temperature of 30-40 ° C galantamine; b) extracting 2-4 times with methyl isobutyl ketone, ethyl or butyl acetate or with n-butanol in an extract / extractant ratio of 8: 1 for extractions in aqueous medium and 2: 1 for extractions in the presence of lower alcohol, respectively; c) concentrating the combined organic extracts obtained in step b) from 1/20 to 1/30 of the initial volume, replacing the solvent with ethanol and treating the resulting galantamine base with hydrobromic acid until it is converted to galanthamine hydrobromide; d) purification of the galantamine hydrobromide obtained from step c) with a purity of 80-86% at a temperature of 80-85 ° C in an aqueous medium with activated carbon and after filtration the purified solution is cooled to 20-25 ° C and alkalized with ammonium hydroxide to pH 9-12; e) extracting 2-4 times the obtained galantamine base with methyl isobutyl ketone, ethyl acetate or butyl acetate in an alkaline aqueous solution / organic solvent ratio of 2: 1 to 3: 1, concentrating from 1/5 to 1/10 of the original volume and cooling; (f) treatment with a selective reagent for N-desmethylgalantamine, in particular with diethyl butyl dicarbonate or with diethyl pyrocarbonate in a molar excess of 1,12-1,2 relative to the content of N-desmethylgalantamine (determined by HPLC) in the alkaloid stirring for 7-10 hours, followed by extraction with mineral acid to pH 2-3 in aqueous medium, alkalizing the acidic aqueous extract of galanthamine salt to pH 9-12; g) extracting the released galantamine base with methyl isobutyl ketone, ethyl acetate or butyl acetate at an aqueous / organic solvent ratio of 2: 1 to 3: 1, replacing the solvent with ethanol and treating with hydrobromic acid to give purified galantamine hydrobromide.