MEMBRANE FILTRATION OF PLANT EXTRACTS BY MEANS OF CYCLODEXTRIN

Abstract

The present invention relates to a method for producing an alcohol-reduced or alcohol-free composition of at least one alcohol-containing plant extract by means of membrane filtration using cyclodextrin.

Claims

1.-14. (canceled)

15. A method for producing a composition of at least one plant extract, the composition having an alcohol content of less than 10 Vol. % comprising the following steps: (a) providing at least one alcohol-containing plant extract, (b) adding at least one cyclodextrin or cyclodextrin derivative, (c) removing the alcohol by means of membrane filtration (permeate) and (d) removing the alcohol-reduced composition (retentate).

16. The method for producing a composition of at least one plant extract according to claim 15, wherein the composition has an alcohol content of less than 5 Vol. %.

17. The method for producing a composition of at least one plant extract according to claim 15, wherein the composition has an alcohol content of less than 1.5 Vol. % wherein an alcohol-free composition is removed in step (d).

18. The method for producing a composition of at least one plant extract according to claim 15, wherein the composition has an alcohol content of less than 5,000 ppm, wherein an alcohol-free composition is removed in step (d).

19. The method for producing a composition of at least one plant extract according to claim 15, wherein the retentate from step (d) is used in step (a) and, is optionally diluted with water.

20. The method for producing a composition of at least one plant extract according to claim 15, wherein the membrane filtration in step (c) is an ultrafiltration, nanofiltration or reverse osmosis.

21. The method for producing a composition of at least one plant extract according to claim 15, wherein the cyclodextrin or cyclodextrin derivative in step (b) is selected from the group consisting of alpha, beta, gamma and delta-cyclodextrin, alkylcyclodextrins, acylcyclodextrins, methyl-β-cyclodextrin, hydroxyalkyl cyclodextrins, and 2-hydroxypropyl-β-cyclodextrin.

22. The method for producing a composition of at least one plant extract according to claim 15, wherein the concentration of cyclodextrin in the liquid plant extract or fluid extract before the membrane filtration is carried out is 0.1-20% m/m.

23. The method for producing a composition of at least one plant extract according to claim 15, wherein the concentration of cyclodextrin in the liquid plant extract or fluid extract before the membrane filtration is carried out is 3.7-4.2% m/m.

24. The method for producing a composition of at least one plant extract according to claim 15, wherein the membrane filtration is carried out with a pressure difference and/or a pressure gradient and/or hydrostatic pressure difference in the range of 5-80 bar.

25. The method for producing a composition of at least one plant extract according to claim 15, wherein the membrane filtration is carried out at a process temperature between 5-60° C.

26. The method for producing a composition of at least one plant extract according to claim 15, wherein the membrane filtration is by reverse osmosis, and is carried out with a pressure difference and/or a pressure gradient and/or hydrostatic pressure difference in the range of 5-80 bar and at a process temperature between 5-60° C.

27. The method for producing a composition of at least one plant extract according to claim 15, wherein the at least one plant extract is selected from a genus from the group consisting of Achillea, Aloe, Althaea, Angelica, Arnika, Artemisia, Cannabis, Capsicum, Carum, Caulophyllum, Centaurium, Chelidonium, Cimicifuga, Citrus, Cyclamen, Cynara, Echinacea, Equisetum, Glycyrrhiza, Guaiacum, Hedeara, Humulus, Iberis, Iris, Juglans, Lavandula, Levisticum, Lilium, Matricaria, Melissa, Mentha, Basilicum (Ocimum), Phytolacca, Pimpinella, Primula, Punica, Quercus, Rosmarinus, Rumex, Salix, Salvia, Sambucus, Silybum, Strychnos, Taraxacum, Thymus, Vaccinium, Valeriana, Vebena, Vitex and Vitis.

28. The method for producing a composition of at least one plant extract according to claim 15, wherein the at least one plant extract is selected from a genus from the group consisting of Thymus and Hedeara.

29. A medicine or food supplement containing an alcohol-free plant extract, the composition having an ethanol content of less than 1.5 Vol. %, but the ethanol content being greater than 0.0 Vol. %, and containing at least one cyclodextrin or cyclodextrin derivative, optionally further additives and auxiliaries.

30. The medicine or food supplement according to claim 29, wherein the composition having an ethanol content of less than 5,000 ppm, but the ethanol content being greater than 0.0 Vol. %, and containing at least one cyclodextrin or cyclodextrin derivative, optionally further additives and auxiliaries.

31. A medicine or food supplement containing an alcohol-free plant extract, the composition having an ethanol content of less than 1.5 Vol. %, but the ethanol content being greater than 0.0 Vol. %, and containing at least one cyclodextrin or cyclodextrin derivative, optionally further additives and auxiliaries obtained by the method according to claim 15.

32. The medicine or food supplement containing an alcohol-free plant extract according to claim 29, wherein the proportion of cyclodextrin or cyclodextrin derivative is 0.1-5% by weight.

33. The medicine or food supplement containing an alcohol-free plant extract according to claim 29, in liquid form selected from the group of drops, juice, syrup, infusion, throat spray and disinfectant solutions, nasal sprays, liquid preparations for inhalation, rinsing solutions, and in combination with physiological and hyperosmolar concentrations of salts or salt mixtures.

34. The medicine or food supplement containing an alcohol-free plant extract according to claim 29, in a medicinal form selected from the group of drops, juice, syrup, infusion, throat spray and disinfectant solutions, nasal sprays, liquid preparations for inhalation, rinsing solutions, and in in combination with physiological and hyperosmolar concentrations of table salt.

Description

EXAMPLES

[0034] The following examples and figures are intended to explain the invention in more detail without, however, restricting it.

Example 1

[0035] 1. Production of the Feed Product for Reverse Osmosis

[0036] First, two exemplary alcoholic extracts from thyme (thymus) and ivy (Hedeara) were produced. A mixture of 90% ethanol, 85% glycerine and a 10% ammonia solution was used as the extraction agent to produce the thyme fluid extract. 70% ethanol was used for the production of the ivy extract. An ivy fluid extract having 57% (V/V) ethanol was produced by concentrating and combining a portion of the ivy extract.

[0037] The two fluid extracts produced, and HP-β-cyclodextrin, were mixed in a ratio of 10:1:1 (fluid extract thyme:fluid extract Hedera:HP-β-cyclodextrin). The present starting product had an ethanol content of 33.091% (V/V) ethanol.

[0038] The mixture was diluted with water in a ratio of 1:1 before reverse osmosis was carried out. The feed product prepared in this way for reverse osmosis contained 4.2% HP-β-cyclodextrin and an ethanol content of 16.304% (V/V).

[0039] An analytical chromatogram was created from the present mixture in order to determine and characterize the entire range of ingredients of the present feed product. This is required in order to be able to determine in the subsequent experiments whether the range of ingredients in the feed product has changed or not.

Example 2

[0040] 2. Ethanol Reduction of the Feed Product Using Cyclodextrin by Membrane Filtration

[0041] A laboratory system customary for membrane filtration was used for dealcoholization of the feed product described in Example 1 using cyclodextrin.

[0042] To determine the filtration effectiveness, the permeate and retentate produced were analytically characterized in addition to the feed product. Here again, an analytical chromatogram was used for determining all ingredients of the feed product.

[0043] The aim of the reverse osmosis was to separate the ethanol contained in the feed by means of membrane filtration, wherein as little as possible of the product ingredients were filtered off into the permeate.

[0044] Two membrane filtration tests were carried out with the same feed product for this purpose.

[0045] A cleaned membrane filtration system was used in the first experiment. In the second experiment, however, the system was preconditioned with the feed product before the main experiment. Here, the system having built-in membrane was operated with the feed before the main test in order to wet the membrane with product. As a result, all free binding sites of the polymeric membrane are bound with molecules of the feed. The product used for preconditioning was discarded.

[0046] The results obtained are summarized in the table below.

TABLE-US-00001 TABLE 1 First experiment using a cleaned membrane filtration system (without preconditioning): Theoretical ethanol content [% V/V] after mixing with other auxiliaries to Ethanol content form the finished Amount [g] [% V/V] medicinal product Before reverse osmosis: Starting 557.4 33.091 6.56 product Feed product 1114.7 16.304 6.52 After reverse osmosis: Concentrate 614.2 15.284 2.44 (retentate) Permeate 474.0 15.550 —

TABLE-US-00002 TABLE 2 Second experiment using a preconditioned membrane filtration system: Theoretical ethanol content [% V/V] after mixing with other auxiliaries to Ethanol content form the finished Amount [g] [% V/V] medicinal product Before reverse osmosis: Starting 559.9 33.091 6.56 product Feed product 1119.8 16.236 6.49 After reverse osmosis: Concentrate 794.1 16.087 2.13 (retentate) Permeate 298.7 15.502 —

[0047] The concentrates produced, which optimally contain all of the product ingredients, constitute the product. The permeate obtained, which ideally only contains ethanol and water and no product ingredients, is discarded as a waste product. The initial volume was reduced by filtering off the permeate.

[0048] Thus, in the two experiments carried out, concentrates could be obtained which now only contain approx. 15-16% (V/V) ethanol, the alcohol content was thus able to be reduced from 33.091% (V/V) to 15-16% (V/V).

[0049] By mixing with further auxiliaries and additives, such as preservatives (including potassium sorbate, sorbic acid, sodium benzoate), pH regulators (including citric acid monohydrate), buffers (including sodium gluconate), solubilizers (including glycerine, monopropylene glycol, polyethylene glycol), viscosity enhancers (including polyvinylpyrrolidone, xanthan gum, sodium carboxymethyl cellulose, sodium alginate, maltodextrin, methyl cellulose), solubilizers (including macrogol glycerol hydroxystearate, octenyl starch succinate), viscosity enhancers (including polyvinylpyrrolidone, xanthan gum, sodium carboyxmethyl cellulose, sodium alginate, maltodextrin, methyl cellulose) sweeteners (including sucrose, maltitol, sorbitol, isomalt, saccharin sodium), flavorings, solvents (purified water), dyes, antioxidants (including ascorbic acid), chelating agents (including sodium EDTA), filtration aids (including cross-linked polyvinylpyrrolidone), a medicinal juice (for example, for children) can only contain approx. 2-3% (V/V) ethanol instead of the 5-6% (V/V) ethanol achieved.

[0050] The concentrate is continuously diluted with water and further subjected to the reverse osmosis process according to the invention to further reduce the ethanol. The ethanol reduction is carried out up to a residual value of approx. 2% ethanol. An alcohol-free finished medicinal product formulation having less than 5000 ppm of ethanol can be obtained by subsequent mixing with the aforementioned auxiliary substances and additives to form the finished medicinal product.

[0051] The evaluation of the analytical chromatograms of the samples from the experiments showed that the ingredient profiles of the feed and concentrate remain unchanged compared to the starting product. No substances whatsoever could be detected in the permeate. In terms of quality, the concentrate produced is identical to the feed and thus to the starting product used.

[0052] The reverse osmosis of an extract mixture with the addition of cyclodextrin is thus extremely effective and advantageous with regard to the retention of product ingredients in the retentate.

Example 3

[0053] 3. Investigation of the Influence of Cyclodextrin on Membrane Filtration

[0054] In a further experiment, the influence of the cyclodextrin in the feed product was specifically investigated when a membrane filtration was carried out. The decisive factor here is whether by adding cyclodextrin, the thymol contained in the feed product can be retained quantitatively more strongly in the retentate and is thus filtered off into the permeate to a lesser extent. Thymol constitutes a very important, pharmacologically relevant ingredient in thyme, but it is one of the low molecular weight compounds, so that it is particularly easy to filter off into the permeate.

[0055] Before the start of the experiment, a mixture of fluid extract thyme, fluid extract ivy and HP-β-cyclodextrin was again prepared as the starting product (mixture in a ratio of 10:1:1, as described in Chapter 1).

[0056] In order to be able to specifically examine the influence of cyclodextrin on membrane filtration, the same fluid extract mixture was prepared, but without the addition of HP-β-cyclodextrin (mixture of fluid extract thyme with fluid extract ivy in a ratio of 10:1).

[0057] Both starting products produced were diluted 1:1 with water so that two identical feed products were produced, one with and one without cyclodextrin.

[0058] The feed product having cyclodextrin prepared in this way contained 3.75% HP-β-cyclodextrin and had an ethanol content of 14.631% (V/V).

[0059] The feed product without cyclodextrin had a measured ethanol content of 14.073% (V/V).

[0060] A laboratory system that is customary for membrane filtration was used to carry out the experiments, with which laboratory system different membranes can be tested simultaneously under the same test conditions. The system was equipped with four different reverse osmosis membranes (membrane A-D) for the experiment.

[0061] In the first run, the membrane filtration was carried out with the cyclodextrin-added feed product. For the second run, new A-D membranes were used with the same conditions, the feed product was filtered without cyclodextrin.

[0062] A quantitative thymol content determination was carried out for all generated permeates for a sensitive, analytical test monitoring.

TABLE-US-00003 TABLE 3 The results of the series of experiments are summarized in the following table: Feed Thymol Thymol with/without content content Recovery HP-β- feed permeate thymol Name cyclodextrin [mg/100 mg] [mg/100 mg] [%] Permeate Membrane A With 0.01927 0.00001 0.05 Permeate Membrane A Without 0.02261 0.00031 1.37 Permeate Membrane B With 0.01927 0.00001 0.05 Permeate Membrane B Without 0.02261 0.00035 1.55 Permeate Membrane C With 0.01927 0.00052 2.70 Permeate Membrane C Without 0.02261 0.00352 15.57 Permeate Membrane D With 0.01927 0.00094 4.88 Permeate Membrane D Without 0.02261 0.00477 21.10

[0063] The evaluation of the analytical results was based on the calculated recoveries of thymol in the permeate. That is, the lower the recovery in the permeate, the lower the transition from thymol to the permeate and the higher the retention of thymol on the retentate side.

[0064] The recoveries of thymol in the permeate were significantly lower when using feed with cyclodextrin than in the experiments without cyclodextrin. Thus, the transfer of thymol into the permeate is particularly low with the use of cyclodextrin.

[0065] This result could be achieved consistently with all membranes, that is, the effect that cyclodextrin more strongly retains the thymol on the retentate side and thus less thymol is found in the permeate, could be determined regardless of the membrane used. This knowledge is reinforced since the experiment series was carried out with the same starting product, under the same test conditions and with different membranes. That is, system-related fluctuations can be excluded.

Example 4

[0066] 4. Carrying Out a Dealcoholization

[0067] The aim of a further experiment is to dealcoholize an extract mixture (starting product) mixed with cyclodextrin, wherein the ethanol content of the starting product is reduced from 25% (m/m) to at least ≤3% (m/m). As a result, a finished medicinal product having ≤0.6% (V/V) or ≤0.5% (m/m) ethanol can be produced from this dealcoholized concentrate by mixing it with other auxiliaries.

[0068] Although the starting product is subjected to a stronger dealcoholization in this experiment, the range of ingredients from the starting product to the concentrate should remain analytically comparable or identical.

[0069] The present experiment was carried out with a larger amount of product and with a pilot plant reverse osmosis system with a membrane module that is customary for membrane filtration.

[0070] Two alcoholic extracts from thyme and ivy, which were prepared in the same way as described in Example 1, were used for the experiment. The two fluid extracts were mixed in a ratio of 10:1:1 with HP-β-cyclodextrin. An ethanol content of 32.79% (V/V) could be analyzed in the present starting product. In addition, an analytical chromatogram was created from the starting product in order to determine the entire spectrum of ingredients and thus the original quality.

[0071] Preconditioning:

[0072] The reverse osmosis system was preconditioned before the dealcoholization process. For this purpose, the system having built-in membrane module with a starting product-water mixture (60.6% starting product, 39.4% water) was run in a cycle in order to wet the polymeric structure of the membrane module with product. The starting product/water mixture used for preconditioning was discarded.

[0073] Dealcoholization:

[0074] The actual dealcoholization process was started after the preconditioning was carried out. A feed mixture was prepared from 19.35% starting product and 80.65% water for the dealcoholization. The feed product present had an ethanol content of 6.31% (V/V) ethanol and contained 1.6% HP-β-cyclodextrin.

[0075] Water was continuously added to the concentrate during the reverse osmosis process in order to continuously reduce the ethanol content in the concentrate. The reverse osmosis was carried out until the concentrate had an ethanol content of ≤3% (m/m) and the amount of concentrate corresponded to the amount of starting product.

[0076] The results of the experiment are summarized in Table 4 below:

TABLE-US-00004 Ethanol content after mixing Amount with further auxiliaries to form [kg] Ethanol content the finished medicinal product Before reverse osmosis: Starting 11.868 32.79% (V/V) // 25.3% (m/m) 6.12% (V/V) // 4.3% (m/m) product Feed product 61.333 6.31% (V/V) // 5.0% (m/m) — After reverse osmosis: Concentrate 11.162 3.81% (V/V) // 2.8% (m/m) 0.62% (V/V) // 0.4% (m/m) (retentate) Permeate 103.117 4.68% (V/V) // 3.7% (m/m) —

[0077] The present results show that the dealcoholization of the starting product was successful and an ethanol content of ≤3% (m/m) could be achieved in the concentrate. The finished medicinal product produced from the concentrate had an ethanol content of 0.4% (m/m) ethanol.

[0078] In the area of herbal active ingredients, the ethanolic aqueous extraction brings a significantly larger range of ingredients into solution than a purely aqueous extraction. This spectrum of active ingredients and ingredients must be preserved through gentle, subsequent dealcoholization, thus preserving the elution power of the ethanol. The analytical investigations of the samples from the experiments therefore focused on examining the changes in the overall composition of the complex mixtures due to reverse osmosis in connection with cyclodextrin.

[0079] As a summary of the findings of the present model experiment with thyme and ivy, it can again be confirmed in this experiment that the dealcoholization of the starting product (starting mixture consisting of thyme fluid extract, ivy leaf extract and cyclodextrin) was successful. The initial ethanol content of 25% (m/m) could be reduced to approx. 2.8% (m/m).

[0080] The other components in the starting product are virtually unchanged in terms of quality and quantity at the end of the process.

TABLE-US-00005 TABLE 5 Qualitative tests - comparison of ingredient profiles before and after dealcoholization End Test parameters Starting product product(s) DC fingerprint on saponins Fingerprint indistinguishable DC fingerprint on flavonoids Fingerprint indistinguishable GC fingerprint (direct Hardly any differences in the injection) RT ranges 6-43 min HPLC MS chromatograms Visually very good agreement of 896 signals

TABLE-US-00006 TABLE 6 Quantitative results - recovery of individual compounds after dealcoholization Recovery in the concentrate in relation to the Quantitative parameters starting product Thymol 99.8% Linalool 102.9% Terpinene-4-ol 98.1% Carvacrol 99.1% Eucalyptol 103.3% Camphor 98.4% Carophylline oxide 111.8% Eugenol 102.0% Hederacoside C 97.0% Agreement GC (sum of the peaks 98.3% according to Ph. Eur. 1374 > LOQ)

[0081] Fingerprints:

[0082] In addition to the quantitative methods, qualitative fingerprint methods were also used to compare profiles. The efficiency of the technology is particularly evident in the substance class of flavonoids and saponins. The cyclodextrin-mediated complexation, which is also described for these substance classes, prevents these substances from being lost during dealcoholization on the opposite side of the membrane into the permeate (see FIGS. 1A and 1B).

[0083] FIGS. 1A and 1B show thin-layer chromatograms (TLC fingerprint).

[0084] The method with direct injection, based on the Ph. Eur. Testing for essential oils of thyme is usually evaluated in the retention time range of 6-43 minutes. The chromatograms presented in FIGS. 2A, 2B and 2C show the comparison of the total chromatograms for the samples starting product, concentrate and permeate.

[0085] In the evaluation range defined above, in which the volatile components of the samples are recorded (among others, essential oil components), the chromatograms of the starting product and concentrate are practically identical. No signals can be seen in the permeate in this range.

[0086] FIGS. 2A, 2B and 2C show GC FID fingerprints.

LITERATURE

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