WO2004041804A2

WO2004041804A2 - Technical process for isolating homoeriodictyol

Info

Publication number: WO2004041804A2
Application number: PCT/EP2003/012108
Authority: WO
Inventors: Jakob Ley; Ingo Reiss; Maria Blings; Petra HOFFMANN-LÜCKE; Jessica Herzog
Original assignee: Symrise Gmbh & Co. Kg
Priority date: 2002-11-08
Filing date: 2003-10-31
Publication date: 2004-05-21
Also published as: AU2003293639A8; WO2004041804A3; DE10252532A1; WO2004041804B1; AU2003293639A1

Abstract

The invention relates to the extraction of technical quantities of pure and natural homoeriodictyols (3`-methoxy-4`,5,7-trihydroxyflavanone) in the form of homoeriodictyol sodium salt and of sterubin (7-methoxy-3`,4`,5-trihydroxyflavanone) from plants of the genus Eriodictyon. To this end, the plant material is extracted using a non-water miscible extractant, the extract is dewaxed, is optionally prepurified using activated carbon, is treated with a sodium ion-containing, basic, aqueous solution, and the precipitated homoeriodictyol sodium salt is purified by reprecipitation or crystallization.

Description

Technical driving for the isolation of flavanones

The invention relates to the production of technical quantities of pure, natural homoeriodictyols (3'-methoxy-4 ', 5,7-trihydroxyflavanone) in the form of the homoeriodicytol sodium salt and sterubin (7-methoxy-3', 4 ', 5 -trihydroxyflavanon)

Plants of the genus Eriodictyon, such that the plant material is extracted with a non-water-miscible extracting agent _, the extract is dewaxed, optionally with activated carbon, pre-cleaned, treated with a basic, aqueous solution containing sodium ions and the precipitated homoeriodictyol sodium salt by reprecipitation or Purifies crystallization.

Homoenodictyol occurs in a variety of plants. The main source, however, is Eriodictyon ssp., Better known as Herba Santa or Yerba Santa, belonging to the family of Hydrophyllaceae. Homoenodictyol or its sodium salt can e.g. can be used as a taste modulator or as an anti-inflammatory agent (Farmaco, Volume 53, 1998, pp. 421-424).

The usual method for the isolation of flavonoids from plant materials is an extraction followed by a chromatographic separation. For the homoerio-dictyol production from Eriodictyon ssp. for example in Biochemical and

Systematics' and Ecology, 1986, Vol. -14, pp. 591ff. described: the plant material is extracted in a mixture of CH C1 ₂ ethyl acetate and then purified several times by chromatography. However, the method is not suitable for larger quantities. , , ^"

To obtain the homoeriodictyol, for example, in J. Am. Chem. Soc., 1940, volume 62, pp. 3258f. the plant material is extracted in a Soxhlet apparatus with diethyl ether, treated in succession with ammonium carbonate solution and sodium carbonate solution, a relatively pure fraction of the homoeriodictyol sodium salt precipitating out. This is then cleaned by crystallization. In principle, the method is suitable for larger preparative approaches, but it is also from a technical point of view Safety-related considerations (handling large quantities of diethyl ether; peroxide formation, risk of explosion) are not suitable for carrying out on an industrial scale.

Another, in Science, 1951, Volume 113, pp. 522f. The method described uses an aqueous extract which is pre-cleaned using an ion exchanger; The raw product is then purified similarly to the previously described method, so that the number of steps is even greater.

It was therefore the object of the present invention to develop a process which can be carried out in large batches, ie on an industrial scale, ^• uses less dangerous working methods or solvents and, in simple steps, high yields of homoeriodictyol or homoeriodictyol- Sodium salt supplies.

The invention therefore relates to a method for obtaining homoeriodictyol sodium salt such that a) the plant material from Eriodictyon ssp. is extracted one or more times with a non-water-miscible extraction agent to the respective boiling point, b) the crude extract thus obtained is separated from the plant material, c) the crude extract is optionally concentrated, d) the crude extract or the concentrated crude extract is temporarily stored, e) the precipitated solids (waxes) are separated off, f) the dewaxed crude extract is optionally treated with activated carbon and removed from the

Solids is separated off, g) the pre-purified crude extract obtained is treated with a basic, aqueous solution containing sodium ions, h) the resulting crude product is separated off in the form of a precipitate containing homoeriodictyol sodium salt, i) this precipitate is optionally washed, j) and optionally the washed crude product is recrystallized from a suitable solvent.

Surprisingly, it was found that in the case of J. Am. Chem. Soc, 1940, volume 62, pp. 3258f. described extraction of the dangerous diethyl ether can be replaced by less problematic solvents such as ethyl acetate or tert-butyl methyl ether without reducing the yield of extracted homoeriodictyol. In addition, a technically much simpler and less expensive extraction at low temperatures by simple stirring or percolation without loss of yield was also possible. Pre-cleaning by a treatment with ammonium carbonate solution described in the last-mentioned literature reference could be deleted without replacement, since the disturbing leaf waxes could easily be separated off (e.g. by decanting or filtration) by partial concentration and cooling. A significant improvement in the quality of the raw product can be achieved by treating the dewaxed crude extract with activated carbon. The homoeriodictyol sodium salt was surprisingly obtained from the crude extract or pre-purified crude extract according to the invention by precipitation with a 10% sodium carbonate solution, similarly to the ethereal extracts, analogously to the literature producing a very fine, difficult to filter precipitate. Surprisingly, the quality of the

Crude product much better if you use an appropriate sodium hydroxide solution for precipitation.

Advantageous extraction means for ^'extraction of the plant material are non-water-miscible, polar solvents such as lower alkyl alkanoates, preferably ethyl acetate or lower, relatively stable oxidation-dialkyl ethers, preferably tert-butyl methyl ether, or mixtures of the aforementioned solvents.

The extraction in ethyl acetate at 0 ° C. to 78 ° C. (boiling heat) at normal pressure is preferred, particularly preferably at 0 ° C. to 40 ° C., in particular at 15 ° to 35 ° C., typically at room temperature, the extraction preferably under Stirring, per- colation, ultrasound or simply standing. If the extraction takes place at boiling temperature, a Soxhlet apparatus can also be used.

Preferred as plant material from Eriodictyon ssp. are the aerial parts, preferably dried, in particular the dried aerial parts of the flowering plants of Eriodictyon californicum (Hook, et Arn.) Torr, (synonym Eriodictyon glutinosum, Wigandia californica) or Eriodictyon angustifolium, the plant parts both as a whole and preferably in comminuted (eg milled or ground) form can be present.

Advantageous weight ratios of plant material to extraction agent are between 1: 200 and 10: 1, preferably between 1: 100 and 1: 1, particularly preferably between 1:10 and 1: 3. The extraction time can be between 1 minute and

72 h, preferably between 0.5 h and 26 h, particularly preferably between 1 and 4 h.

A repetition of the extraction of already extracted plant material is particularly advantageous, the repetition being carried out 1 to 10 times, preferably 1 to 5 times, particularly preferably 1 to 2 times.

Preference is given to concentrating the crude extract to 60 to 10% by weight, preferably 45 to 20% by weight, of the original mass of the crude extract, this concentration being carried out, for example, by gentle distillation, preferably distillation in vacuo at temperatures below 40 ° C. ,

The intermediate storage of the crude extract or the concentrated crude extract is advantageously carried out at -10 ° C to 50 ° C for a period of 1 to 10 days, preferably at 0 to 10 ° C for 10 to 72 h. Leaf waxes in the form of paraffins precipitate, which are separated off by filtration or decanting. The dewaxed crude extract is preferably cleaned by treatment with activated carbon, with the batch of activated charcoal advantageously advantageously being stirred with the dewaxed crude extract or the dewaxed crude extract being percolated through a column packed with activated carbon.

The basic aqueous solution containing sodium ions is preferably a sodium carbonate solution, a sodium hydrogen carbonate solution or a sodium hydroxide solution which has a pH in the range from greater than 7 to 14. Aqueous solutions with 1 to 20% by weight sodium carbonate, 1% by weight to saturation of sodium hydrogen carbonate, or 1 to 15% by weight sodium hydroxide are preferred.

Aqueous solutions with 8 to 12% by weight sodium carbonate, 5 to 10% by weight sodium bicarbonate or 1 to 10% by weight _: % sodium hydroxide are particularly preferred.

The treatment of the pre-purified crude extract with a basic, aqueous solution containing sodium ions can be carried out at 0 to 40 ° C, preferably at 0 to 25 ° C, particularly preferably at 5 to 15 ° C, the crude product being the homoerodi-ethylene glycol sodium salt Precipitation fails. The weight ratio of the pre-cleaned crude extract to the basic aqueous solution containing sodium ions can be 1:10 to 10: 1, preferably 1: 2 to 5: 1. The precipitation can be carried out by immediately mixing or dropping the basic, aqueous solution containing sodium ions into the crude extract while standing, stirring, shaking or under the action of ultrasound, preferably with stirring.

The crude product in the sense of the invention can be washed with a solvent, preferably water, the suitable solvent for extraction, preferably ethyl acetate, with ethanol, methanol or mixtures of the abovementioned solvents, the solvent advantageously having a temperature of 0 to. 40 ° C, preferably 0 to 25 ° C, particularly preferably 5 to 15 ° C. The washed crude product can be recrystallized from suitable solvents or mixtures thereof, the crude product being dissolved in whole or in part at 25 ° C. to the boiling point and the resulting solution or suspension being cooled, the product precipitating. If necessary, the recrystallization can be repeated one or more times.

Water, ethanol, methanol, methanol, ethyl acetate, acetone or isopropanol or mixtures of the abovementioned solvents can be used as suitable solvents for recrystallization in the sense of the invention. -.

A particularly advantageous embodiment of the recrystallization within the meaning of the invention is carried out in such a way that the crude product is in a water / acetone mixture, preferably a water / acetone mixture with the weight ratio 1 ^' : 5 to 5: 1, at 0 to 100 ° C, preferably 15 to 40 ° C, partially or completely dissolves and the acetone is gently or partially distilled off, preferably in

Vacuum below 40 ° C, whereby the homoeriodictyol sodium salt fails in pure form.

The separations in the sense of the invention can be carried out by filtration, centrifugation, decanting and other customary methods for separating solids from liquids.

A particularly preferred embodiment of the invention is to carry out the entire process under an inert gas, for example nitrogen, carbon dioxide, a noble gas, in particular argon, in order to suppress the oxidation processes which reduce the yield during processing.

The homoeriodictyol sodium salt obtained by the process described can be obtained by recrystallization from glacial acetic acid (cf. in J. Am. Chem. Soc, 1940, volume 62, p. 3258f.) Or by ion chromatography (Science, 1951, volume 113, p. 522f .) to be converted into the free homoeriodictyol. Another invention relates to the extraction of sterubin from the filtrate, the treatment of the pre-purified crude extract with a basic aqueous solution containing sodium ions (ie the filtrate which is present after step h) described above) in such a way that i) the aqueous from the organic Phase of the filtrate is separated, ii) the organic phase is partially concentrated by distillation, preferably distillation in vacuo at <40 ° C., iii) the precipitate formed is separated from sterubin, iv) if necessary, the crude sterubin is recrystallized from a suitable solvent.

The following examples illustrate the invention.

Examples

Example 1: Comparative experiment according to J. A. Chem. Soc, 1940, volume 62, pp. 3258f.

Herba Santa cabbage (70 g, dried, rubbed) was extracted with diethyl ether (500 ml) in a Soxhlet apparatus for 10 h and the intense green extract after filtration was washed with ammonium carbonate solution (200 ml, 50 g / 1). After filtration, the filtrate was treated with ice-cold sodium carbonate solution (450 ml, 100 g / 1), whereby a thick yellow precipitate separated out. The product was filtered off and recrystallized from water (65 ml): 1.63 g, 2.3% mass yield, based on the

Plant material (HPLC 100%).

Example 2: Extraction in a Soxhlet with ethyl acetate, precipitation of Na? CO ₃

Herba Santa cabbage (100 g, dried, milled) was extracted with ethyl acetate (1300 ml) in a Soxhlet apparatus for 10 h and concentrated to approx. 40% by weight (<40 ° C., vacuum). After storage at 4 ° C. overnight, the leaf wax was filtered off and the filtrate was treated with ice-cold sodium carbonate solution (450 ml, 10% by weight), a yellow precipitate being formed. The product was filtered off (3.95 g of crude product) and recrystallized from water: 1.96 g, 2% mass yield, based on the plant material (HPLC 96%).

Example 3: Extraction in tert-butyl methyl ether, precipitation of Na? CO ₃

Herba Santa herb (70 g, dried, rubbed) was treated with tert-butyl methyl ether

(a total of 500 ml) extracted 3 times at 40 ° C. and treated with ice-cold sodium carbonate solution (150 ml, 10% by weight), a yellow precipitate being formed. The crude product was filtered off (3.72 g) and recrystallized from water: 1.60 g, 2.3% mass yield, based on the plant material (HPLC 96%).

Herba Santa herb (200 g, dried, milled) was extracted with ethyl acetate (660 ml) at 40 ° C. for 16 h with stirring and the plant material was filtered off; the plant material was extracted twice using this method. The crude extract was concentrated to 25% by weight in vacuo at <40 ° C. and stored at 4 ° C. for 16 h. After filtration, the dewaxed crude extract was treated with 10 g of activated carbon and filtered. To the prepurified crude extract, 1/3 part by weight of 10% strength by weight sodium carbonate solution was added at 5-10 ° C. and the mixture was stirred for a while. The precipitate is filtered off through a Büchner funnel. The moist filter cake

(Crude product) was recrystallized from water (7 parts of water to 1 part of crude product). Yield: 3.64 g, 1.8% mass yield, based on the plant material (HPLC 100%).

The homoeriodictyol sodium salt obtained in this way was characterized analytically:

1H-NMR (200 MHz, CD ₃ OD): δ = 7.08 (1H, d, 2 Hz), 6.92 (1H, dd, 8 Hz, 2 Hz), 6.81 (1H, d, 8 Hz), 5.65 (2H, AB system), 5.23 (1H, dd, 12 Hz, 3 Hz), 3.86 (3H, s), 2.99 (1H, dd, 16.5 Hz , 12 Hz), 2.57 (1H, dd, 16.5 Hz, 3 Hz) ppm 1 ³ C-NMR (100 MHz, CD ₃ OD, + DC1): 196.38 (C), 166.74 ( C), 163.33 (C), 162.87 (C), 147.53 (C), 146.90 (C), 129.41 (C), 119.64 (CH), 115.19 (CH ), 111.14 (CH),

101.70 (C), 95.85 (CH), 95.07 (CH), 78.69 (CH), 55.71 (CH ₃ ), 42.11 (CH ₂ ) ppm MS (HPLC-MS, APCI +): m / z = 301.20 (100%), 302.15 (16.1%), 303.07 (3.9%) Elemental analysis: The product contains 6.2% sodium (flame atomic absorption spectroscopy); this corresponds to 1 sodium per formula unit.

Example 5: Extraction in ethyl acetate, cold, activated carbon, precipitation of Na7CO ₃

Herba Santa herb (20 kg, dried, rubbed) was added with ethyl acetate (100 1)

20 ° C extracted for 24 h with stirring and the plant material filtered off; the plant material was extracted twice using this method. The crude extract was concentrated to 12.5% by weight at 80 ° C./1013 mbar and stored at 0-10 ° C. To Filtration, the dewaxed crude extract was mixed at 0-10 ° C with 12 kg of 10 wt .-% sodium carbonate solution and stirred for 1 hour. The precipitate was separated from the bulk of the solvents by decanting (32 kg organic phase, mother liquor) and the suspension was then filtered; the moist filter cake was washed in a pressure filter with 2 kg of ethyl acetate and dried in a vacuum drying cabinet at 40 ° C. (1200 g of crude product).

30 g of the crude product were recrystallized from water. Yield: 12.7 g. Extrapolated, this corresponds to a mass yield of 2.5%, based on the plant material (HPLC 100%; 80%, based on free homoeriodictyol).

Example 6: Extraction with ethyl acetate, hot, precipitation NaOH

Herba Santa cabbage (50 g, dried, rubbed) was extracted with ethyl acetate (650 ml) in a Soxhlet apparatus for 10 h and concentrated to approx. 40% by weight (<40 ° C.,

Vacuum). After storage at 4 ° C. overnight, the leaf wax was filtered off and the filtrate was treated with ice-cold sodium hydroxide solution (450 ml, 10% by weight), a yellow precipitate being formed. After standing for a long time, the product was filtered off and washed with 20 ml of water: 1.12 g, 2.2% mass yield, based on the plant material (HPLC 72%, based on free homoeriodictyol, no further flavanones).

Example 7: Extraction with ethyl acetate, cold, precipitation with slightly concentrated NaOH

Herba Santa cabbage (100 g, dried, rubbed) was mixed with 2 portions of ethyl acetate

(500 ml each) stirred for 1 h and then filtered. The ethyl acetate extracts were combined and concentrated to approx. 20% by weight (<40 ° C., vacuum). After storage at 4 ° C. overnight, the leaf wax was filtered off and the filtrate was treated with ice-cold sodium hydroxide solution (60 g, 3% by weight. ig) treated, whereby a yellow precipitate failed. After standing at 0 ° -5 ° C. overnight, the product was filtered off and washed with 20 ml of water and dried: 2.45 g, 2.4% mass yield, based on the plant material (HPLC 100%, based on free homoeriodictyol).

Example 8: recrystallization from water / acetone

10 g of the crude product from Example 5 were dissolved at 65 ° C. in about 100 ml of a mixture of water / acetone (1: 1, parts by weight). After storage in the refrigerator, the precipitate was filtered off (I); the mother liquor was largely freed from acetone at <40 ° C. in vacuo, a further precipitate precipitating (U). Yield combined (I + H): 6 g (HPLC 80%, based on free homoeriodictyol).

Example 9: Sterubin production

The organic phase of the mother liquor of the crude product from Example 5 (5 l) was concentrated to about 500 ml at <40 ° C. in vacuo and the precipitate formed was filtered off. The crude product is boiled in 800 ml of ethyl acetate, filtered again and the recrystallized product is washed with ether. Yield 32 g, approx. 1% mass yield, extrapolated (HPLC 94%)

Claims

Patentansprttche

1. A process for obtaining homoeriodictyol sodium salt, characterized in that a) the plant material from Eriodictyon ssp. is extracted one or more times with a non-water-miscible extraction agent to the respective boiling point, b) the crude extract thus obtained is separated from the plant material, c) the crude extract is optionally concentrated, d) the crude extract or the concentrated crude extract is temporarily stored, e) the precipitated solid (waxes) are separated, f) the dewaxed crude extract is optionally treated with activated carbon and separated from the solid, g) the pre-cleaned crude extract obtained is treated with a basic, aqueous solution containing sodium ions, h) the resulting crude product in the form of a homoeriodictyol Precipitate containing sodium salt is separated, i) this precipitate is optionally washed, j) and optionally the washed crude product from a suitable

Solvent is recrystallized.

2. The method according to claim 1, characterized in that the extracting agent is chosen from lower alkanoic acid alkyl esters, preferably ethyl acetate, or lower, relatively oxidation-stable dialkyl ethers, preferably tert-butyl methyl ether, or mixtures of the aforementioned extraction agents.

3. The method according to claim 1 or 2, characterized in that the extraction in ethyl acetate at 0 ° C to 78 ° C at normal pressure, preferably at 0 ° C to

40 ° C, is carried out. Method according to at least one of claims 1 to 3, characterized in that the aerial parts, preferably dried, in particular the dried aerial parts of the flowering plants of Eriodictyon californicum (Hook, et Arn.) Torr, or Eriodictyon angustifolium are used as the plant material.

Method according to at least one of claims 1 to 4, characterized in that the crude extract is concentrated to 60 to 10% by weight, preferably 45 to 20% by weight, of the original mass of the crude extract.

Method according to at least one of claims 1 to 5, characterized in that after the intermediate storage of the crude extract or the concentrated crude extract at -10 ° C to 50 ° C for 1 to 10 days, preferably at 0 to 10 ° C for 10 up to 72 h and the solids that precipitate are separated off.

Method according to at least one of claims 1 to 6, characterized in that the basic, aqueous solution containing sodium ions

Sodium carbonate solution, a sodium bicarbonate solution or a sodium hydroxide solution which has a pH in the range from greater than 7 to 14.

Method according to at least one of claims 1 to 7, characterized in that the entire process is carried out under an inert gas.

Process for obtaining sterubin from the after step h). Filtrate present according to claim 1, characterized in that: i) the aqueous phase is separated from the organic phase of the filtrate, ii) the organic phase by distillation, preferably distillation in

Vacuum partially concentrated at <40 ° C, iii) separating the precipitate from Sterubm, iv) optionally recrystallizing the crude sterubin from a suitable solvent.