ZA200502494B

ZA200502494B - Method for extracting a natural mixture of conjugated equine estrogens that is deplated of non-conjugated lipopilic compounds

Info

Publication number: ZA200502494B
Application number: ZA200502494A
Authority: ZA
Inventors: Ivan Ban; Klaus-Guenther Gerling; Hans-Joerg Mueller; Stefan Wachsmann
Original assignee: Solvay Pharm Gmbh
Priority date: 2002-10-11
Filing date: 2005-03-29
Publication date: 2006-07-26
Also published as: TW200409779A; NO332770B1; DK1553959T3; ES2324533T3; EP1553959B1; CN1691951A; CN100542542C; JP4778233B2; RU2329818C2; JP2006505561A; PL374684A1; BR0314639A; NO20052286D0; AU2003301237B2; PT1553959E; AU2003301237A1; RU2005114481A; CA2498095A1; HK1083450A1; EP1553959A1

Description

The present invention relates to obtaining a natural mixture of conjugated equine oestrogens which is depleted in non-conjugated lipophilic compounds from the group comprising non-conjugated flavonoids, non-conjugated isoflavonoids, non-conjugated norisoprenoids, non-conjugated steroids, in particular androstane and pregnane steroids, and comparable non-conjugated compounds.

Oestrogens are used in medicine for hormone replacement therapy. In particular, oestrogen mixtures are used for the treatment and prophylaxis of the disorders of the climacteric period which occur in women after natural or artificial menopause. In this case, natural mixtures of conjugated oestrogens such as are found in the urine of pregnant mares, hereafter referred to as natural mixtures of conjugated equine oestrogens, have proved particularly effective and readily compatible.

The dissolved solids content in the urine of pregnant mares (= pregnant mares’ urine, abbreviated hereafter as "PMU") can naturally fluctuate within wide ranges, and may generally lie in a range of 40 to 90 g dry matter per litre. In addition to urea and other usual urine contents, phenolic constituents are contained in the solids content of the PMU in quantities of about 2 to 5% by weight relative to the dry matter. These phenolic con- stituents include cresols and dihydro-3,4-bis[(3-hydroxyphenyl)methyl]-2(3H)-furanone, known as HPMF. These may be present in free or conjugated form. The PMU contains a natural mixture of oestrogens which is largely present in conjugated form, e.g. as sul- phuric acid semi-ester sodium salt (abbreviated hereafter as "sulphate salt"). The content of conjugated oestrogens (calculated as oestrogen sulphate salt) may be between 0.1 and 1% by weight, relative to the dry matter. In addition, further lipophilic compounds may be present in the solids content of the PMU, the quantities of which compounds can fluctuate within wide ranges and cannot be predicted. These lipophilic compounds originate pre-

dominantly from the plants ingested as food by the pregnant mares and comprise above all various flavonoid, isoflavonoid and norisoprenoid derivatives and comparable com- pounds, such as for example formononetin, genistein, daidzein, biochanin A, equol and coumestrol. These lipophilic compounds originally of plant origin may be present in the urine in conjugated or in free (non-conjugated) form. The lipophilic constituents further- more occurring in the solids content of the PMU also include non-conjugated steroid derivatives; of these in particular the androstane and pregnane steroids, but also non- conjugated oestrogen derivatives should be mentioned.

Extracts containing natural mixtures of conjugated oestrogens are usually obtained either by means of a solid-phase extraction method or by a method based on various liquid-liquid extraction steps with organic solvents which are not miscible, or only slightly miscible, with water. Generally speaking, in order to be able to be used as active sub- stance constituent for pharmaceuticals, the natural mixture of conjugated oestrogens which is obtained must meet certain pharmaceutical specifications, for example meet the specification laid down in the USP (United States Pharmacopeia) or European Pharmaco- poeia. For example, certain limit values must be observed with regard to the content of conjugated oestrogens relative to the dry matter.

US Patents No. 2,551,205 and No. 2,429,398 describe a process for the prepara- tion of a water-soluble oestrogen preparation from PMU, in which initially an aqueous concentrate is obtained by adsorption on activated carbon or other suitable adsorber materials, elution with a water-miscible organic solvent, such as pyridine, and subsequent removal of the solvent, which concentrate contains the major part of the water-soluble oestrogen constituents of the PMU originally used. Whereas in US Patent No. 2,429,398 the concentrate is further purified by extraction with benzene and/or ether, US Patent No. 2,551,205 discloses acidulating the concentrate to a pH value of between 2 and 6, pref- erably between 4 and 5, and then rapidly extracting it with a organic solvent which is only slightly miscible with water from the group of aliphatic, aromatic or alicyclic hydrocarbons (e.g. hexane, benzene, toluene, cyclohexane) or the chlorinated hydrocarbons (e.g. chloroform, ethylene dichloride, trichloroethylene, carbon tetrachloride, chlorobenzene), in order to separate off undesirable substances such as fats, oils, free phenolic constituents and the non-conjugated steroids by transferring into the organic phase. Finally, the aque- ous phase is stabilised by neutralisation. US Patent No. 2,551,205 recommends further purifying the extract obtained by subsequent extraction steps and precipitation operations.

Overall, after performing the method described in US Patent No. 2,551,205 an yield of : only about 80% of the oestrogen constituents of the concentrate used is obtained.

US Patent No. 2,565,115 describes the extraction of the conjugated oestrogens from PMU with acetone. No statement is made about the purity of the resulting oestrogen fraction.

US Patent No. 2,696,265 describes a method in which initially the oestrogens are extracted with an aliphatic alcohol or ketone, such as hexanol, cyclohexanol or cyclohex- anone. The oestrogens pass into the organic phase and are then further purified; inter alia, an aqueous phase containing the oestrogens is set to a pH value of 4 with hydrochlo- ric acid and extracted with ethylene dichloride.

US Patent No. 2,834,712 discloses a method for the preparation of oestrogen mix- tures of significant purity and low toxicity which is based on a large number of individual extraction steps with different solvents and the setting of different pH values. In that method, large volumes of solvents such as hexane and benzene are used. Thus for example in one step an already purified concentrate is dissolved in water, set with hydro- chloric acid to a pH value of approximately 5.0 and extracted with benzene and then with ether, in order to separate off the phenolic constituents.

International patent application WO 01/27134 describes a comparatively simple method of extracting conjugated oestrogens from PMU: after the addition of a salt, such as sodium chloride, the PMU is extracted with at least the same volume percent of an organic solvent, such as ethyl acetate, whereupon the conjugated oestrogens pass into the organic phase. The organic phase is separated off and dried in order to obtain the extract. No statements are made in WO 01/27134 about the purity of the extract of conju- gated oestrogens which is obtained.

With the liquid-liquid-extraction method described above and known from the prior art, however, a number of problems occur, such as vigorous foaming, sediment formation, emulsification and poor phase separation. Generally several extraction steps are required, which results in losses and only partial obtention of the oestrogen content. Furthermore, these extraction methods require large volumes of solvents some of which are harmful to health. Furthermore, in the patent specifications listed above no statements are made either about the content of non-conjugated lipophilic constituents, such as for example non-conjugated flavonoid, isoflavonoid and norisoprenoid derivatives and comparable : non-conjugated compounds, or also non-conjugated steroids, in particular androstane and pregnane steroids, in the products obtained, nor about separation of these constituents.

These methods known from the prior art either provide no satisfactory results with regard to the yield or with regard to the purity of the extract obtained, measured on the total hormone content obtained relative to the dry matter, or they are based on a large number of different method steps and the use of large volumes of organic solvents some of which are undesirable even from a toxicological point of view. :

Furthermore various solid-phase-extraction methods are known from the prior art for obtaining a natural mixture of conjugated equine oestrogens largely depleted in pheno- lic urine contents. Thus international patent application WO 98/08526 describes a method with which a largely cresol- and HPMF-free mixture which is depleted in phenolic urine contents and contains the natural oestrogen content of the PMU practically completely can be obtained in a solid-phase extraction on a semipolar, in particular non-ionic semipo- lar, polymeric adsorption resin. International patent application WO 98/08525 describes a similar method in which silica gel is used as adsorber material in the solid-phase extrac- tion. Also Chinese patent application CN 1308083 describes a comparable method in which polar adsorption resins containing cyano groups are used. The extracts obtained are suitable as starting material for the preparation of pharmaceuticals which contain the natural mixture of conjugated oestrogens from PMU as active substance constituent.

The pharmaceutical specification requirements laid down, for example the limit values to be observed with regard to the content of conjugated oestrogens relative to the dry matter, are normally met by the mixtures of conjugated oestrogens obtained from

PMU in accordance with the method of WO 98/08526 or the method of WO 98/08525. It has however turned out that in addition to the desired content of conjugated oestrogens also non-conjugated lipophilic compounds may be contained in the dry matter obtained.

The non-conjugated lipophilic compounds include for example various non-conjugated flavonoid, isoflavonoid and norisoprenoid derivatives and comparable non-conjugated compounds, such as for example formononetin, genistein, daidzein, biochanin A, equol and coumestrol, but also non-conjugated steroids, in particular androstane and pregnane steroids, and non-conjugated oestrogens; this list should not be regarded as definitive.

The presence of the non-conjugated lipophilic compounds in the mixture of conjugated oestrogens obtained from the PMU cannot be standardised, but both the content and the composition of the free and conjugated lipophilic compounds varies for example according to the food ingested by the pregnant mares.

Although the composition of the natural mixture of conjugated equine oestrogens 5 does not change due to the additional presence of the non-conjugated lipophilic com- pounds, the content of the conjugated equine oestrogens relative to the dry matter can be reduced. A higher concentration of the active substances, i.e. the conjugated equine oestrogens, in the extract obtained could be achieved by deliberate separation of the non- conjugated lipophilic constituents. Also for reasons of medicament safety it may be useful to separate off the non-conjugated lipophilic compounds in order to ensure a uniform composition of individual! extract batches, since in this way the non-conjugated lipophilic constituents, the content and composition of which in the PMU can vary according to the seasonally changing type of food ingested by the pregnant mares, can be eliminated, and thus the resulting extracts would all have a comparable content of conjugated equine oestrogens relative to the dry matter. Furthermore, separation of the non-conjugated lipophilic compounds may be advantageous in order to obtain a uniform physiological spectrum of action. For example, it may be useful to separate off possibly present, non- conjugated lipophilic compounds, which may possibly themselves have an undesirable physiological effect, from the natural mixture of conjugated equine oestrogens.

It is therefore an object of the present invention to develop a technically and eco- nomically optimum method for obtaining a natural mixture of conjugated equine oestro- gens, the mixture of non-conjugated lipophilic compounds, in particular of non-conjugated flavonoid, isoflavonoid and norisoprenocid derivatives being largely depleted. In particular, it is the object of the present invention to develop such a method in which only small quantities of solvent which is not harmful to the health are used. Furthermore, a method should be developed which is based on only a few method steps and yields an extract of conjugated equine oestrogens which has a comparatively high content of conjugated oestrogens relative to the dry matter. Furthermore, it should be possible, using the method of the present invention, in a simple manner to treat a mixture, already depleted in pheno- lic urine contents, of conjugated oestrogens from pregnant mares’ urine which may con- tain changing and possibly elevated quantities of non-conjugated lipophilic compounds such that the natural mixture of conjugated equine oestrogens obtained with the present invention has good active substance contents and meets the required pharmaceutical specifications; in particular it should observe the necessary limit values with regard to the content of conjugated oestrogens relative to the dry matter.

A method has now been found with which, in a surprisingly simple manner, a mix- ture of conjugated equine oestrogens can also be obtained from a changing PMU having possibly elevated quantities of non-conjugated lipophilic compounds, the mixture of 5 conjugated equine oestrogens obtained being largely depleted in non-conjugated lipophilic compounds, in particular non-conjugated flavonoid, isoflavonoid and norisoprenoid deriva- tives. In particular, the method according to the invention can be applied to a mixture of conjugated oestrogens from pregnant mares’ urine already depleted in phenolic urine contents, so that with the method a mixture of conjugated equine oestrogens is obtained which has a high product quality and reliably meets the requirements of the pharmaceuti- cal specification, in particular also with regard to the limit values to be observed with regard to the content of conjugated oestrogens relative to the dry matter.

The method according to the invention for obtaining a natural mixture of conju- gated equine oestrogens [is] characterised in that the mixture obtained is depleted in non- conjugated lipophilic compounds from the group comprising non-conjugated flavonoids, non-conjugated isoflavonoids, non-conjugated norisoprenoids, non-conjugated steroids, in particular androstane and pregnane steroids, and comparable non-conjugated com- pounds, and that the method is distinguished in that a) an aqueous initial phase, selected from the group comprising (iy an aqueous solution of a natural mixture, already depleted in phenolic urine contents, of conjugated oestrogens from pregnant mares' urine, (i) an aqueous concentrate of a natural mixture, already depleted in pheno- lic urine contents, of conjugated oestrogens from pregnant mares’ urine, (ii) a concentrate of a urine liquid, and (iv) a urine concentrate, optionally pre-purified by filtration, is subjected to a liquid-liquid extraction with a sufficient quantity of an extracting : agent which represents an organic solvent suitable for the extraction of non- conjugated lipophilic compounds from the above group, and which is not misci- ble, or only slightly miscible, with water, and subsequently the aqueous phase is separated off, and b) optionally method step (a) is repeated with the resulting aqueous phase, and c) an aqueous phase containing the natural mixture of conjugated oestrogens is obtained and optionally concentrated.

For the method according to the invention an aqueous solution (i) of a natural mix- : ture, already depleted in phenolic urine contents, of conjugated oestrogens from pregnant mares' urine, or an aqueous concentrate (ii) of a natural mixture, already depleted in phenolic urine contents, of conjugated oestrogens from pregnant mares' urine may be used as aqueous initial phase. This aqueous solution or this aqueous concentrate may be obtained by a method such as has already been described for example in international patent applications WO 98/08526 and WO 98/08525 or in Chinese patent application CN 1308083 and is thus familiar to the person skilled in the art from these published patent applications. The contents of WO 98/08526, WO 98/08525 and CN 1308083 are also made the subject of the present application for the purposes of the disclosure. An aque- ous solution or an aqueous concentrate of a natural mixture, already depleted in phenolic urine contents, of conjugated oestrogens from pregnant mares’ urine may also be the product of a liquid-liquid extraction process, such as described for example in international patent application WO 01/27134. The aqueous solutions or concentrates obtained accord-: ing to the methods described in the above patent applications can be further concentrated before their use in the method according to the invention in known manner, such as for example by distillation, in order to obtain a concentrate largely freed of organic solvent.

Furthermore a concentrate (iii) obtained from the PMU by concentration or a con- centrate (iv) obtained from the PMU, which has already been pre-purified by filtration or comparable methods may be used as aqueous initial phase for the method according to the invention. The collected urine (PMU) is first freed in known manner from mucilaginous substances and solids. Expediently, solids and mucilaginous substances are allowed to settle and are then separated off using known separation methods, for example decant- ing, separation and/or filtering. Thus the PMU may be passed for example through a known separating means, e.g. a separator, a filtration unit or a sedimenter. A sand bed for example may serve as separating means, or commercially available separators may be used, e.g. nozzle or chamber separators. If desired, a microfiltration unit or an ultrafiltra- tion unit may also be used, and if these are used it is possible to achieve a largely bacte- ria-free and virus-free filtered PMU at the same time.

If desired, preservatives, germicides, bactericides and/or anthelmintics may be added to the urine or the urine concentrate.

A concentrated PMU retentate which can be obtained from the PMU by known membrane filtration can also be used as pre-purified urine concentrate (iv). The solids

Claims

1. A method for obtaining a natural mixture of conjugated equine oestrogens, characterised in that the mixture obtained is depleted in non-conjugated lipophilic com- pounds from the group comprising non-conjugated flavonoids, non-conjugated isoflavon- oids, non-conjugated norisoprenoids, non-conjugated steroids, and comparable non- conjugated compounds, and that the method is distinguished in that a) an aqueous initial phase, selected from the group comprising (i) an aqueous solution of a natural mixture, already depleted in phenolic urine contents, of conjugated oestrogens from pregnant mares’ urine, (ii) an aqueous concentrate of a natural mixture, already depleted in pheno- lic urine contents, of conjugated oestrogens from pregnant mares’ urine, (iii) a concentrate of a urine liquid obtained by concentration, and (iv) a urine concentrate, freed from mucilaginous substances and solids by mechanical separation methods, or a concentrated urine retentate ob- tained by filtration is subjected to a liquid-liquid extraction with a sufficient quantity of an extracting agent and subsequently the aqueous phase is separated off, whereby the ex- tracting agent represents an organic solvent suitable for the extraction of non- conjugated lipophilic compounds from the above group, is not miscible, or only slightly miscible, with water, and is selected from the group consisting of straight-chain, branched or cyclic C4-C4o alcohols, C.-C; esterified acids, Cs-Cyo aldehydes, C4-C4, ketones, C,-Cyo ethers, Cs-Cs nitriles and C4-C; haloalkanes, and mixtures of the aforementioned solvents, and b) optionally method step (a) is repeated with the resulting aqueous phase, and Cc) an aqueous phase containing the natural mixture of conjugated oestrogens is obtained and optionally concentrated.

2. A method according to Claim 1, wherein the non-conjugated steroids are an- drostane and pregnane steroids.

3. A method according to Claim 1 or 2, wherein an aqueous solution (i) of a natu- ral mixture, already depleted in phenolic urine contents, of conjugated oestrogens from pregnant mares’ urine, or an aqueous concentrate (ii) of a natural mixture, already de- AMENDED SHEET 24.02.2006 pleted in phenolic urine contents, of conjugated oestrogens from pregnant mares’ urine is used as aqueous initial phase in method step (a).

4. A method according to one of the preceding claims, wherein the depletion in phenolic urine contents was obtained in a solid-phase extraction on a non-ionic semipolar adsorption resin or on a hydrophobized silica gel.

5. A method according to one of the preceding claims, wherein the extracting agent is selected from the group consisting of C,-C,-alkyl acetates, hexanol, diethyl ether, methylene chloride, methyl tert.-butyl ether and mixtures of the aforementioned solvents.

6. A method according to Claim 4, wherein the extracting agent is C;-C,-alkyl acetate.

7. A method according to Claim 6, wherein the C,-C4-alkyl acetate is ethyl ace- tate.

8. A method according to one of Claims 1 to 7, wherein in method step (a) the aqueous initial phase is set to a pH value in the range between 4 and 12.

:

9. A method according to Claim 6, wherein the pH value is set in the range of 4.0 to 7.0.

10. A method according to Claim 9, wherein the pH value is set in the range of 4.0

106.0.

11. A method according to Claim 10, wherein the pH value is set in the range of

4.7 t0 5.3.

12. A method according to one of Claims 1 to 11, wherein in method step (a) the volume ratio of the aqueous initial phase to the extracting agent lies in the range of 5:1 to

1:3.

13. A method according to Claim 12 wherein in method step (a) the volume ratio of the aqueous initial phase to the extracting agent lies in the range of 2:1 to 2:2. : AMENDED SHEET 24.02.2006

14. A method according to one of Claims 1 to 8, wherein in method step (b) the volume ratio of the aqueous initial phase obtained from method step (a) to the extracting agent lies in the range of 20:1 to 1:1.

15. A method according to Claim 14, wherein in method step (b) the volume ratio of the aqueous initial phase obtained from method step (a) to the extracting agent lies in the range of 10:1 to 2:1.

16. A method according to claim 1 substantially as herein described with reference to either example 1 or 2. AMENDED SHEET 24.02.2006 :