RU2259991C2 - Method for preparing polyprenols - Google Patents

Abstract

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to methods for preparing polyprenols that elicit the biological activity. Polyprenols are prepared from fir wood greens by extraction of dried and milled raw and the following purification of the end product. The raw extraction is carried out for two stages. Firstly, fir wood greens milled to particles size 5 mm, not above, is extracted with fluidized carbon dioxide for 3 h under subcritical conditions at temperature less 31.1°C and under pressure less 72.5 atm and removing components of fir oils. At the second stage the depleted wood greens is extracted with fluidized carbon dioxide for 2 h under supercritical conditions at temperature above 31.1°C and under pressure above 72.5 atm. Method provides elective preparing polyprenol acetates with high yield and purity.

EFFECT: improved preparing method.

2 ex

Description

The invention relates to methods for producing polyprenols that have biological activity [Grigoryeva N.Ya., Moiseenkov P.M. The physiological activity of polyisoprenoids. - Chem. farm. Journal, 1998, No. 2, pp. 144-145]

Polyprenols are a natural mixture of oligomers (isoprenologists). This mixture behaves as a single substance and is separable only on reversed-phase sorbents [Ibatak et al. Long-chain polyprenols in the family Pinaceal Phytochemistry 23, 1984, p. 783-786]. Polyprenols are contained as acetates in the needles of trees of a number of species of the pine botanical family [Ibatak et al. Long-chain polyprenols in the family Pinaceal Phytochemistry 23, 1984, p. 783-786], which is the richest source of their production and, at the same time, waste during the harvesting of wood.

A known method for the isolation of polyprenols from the needles of conifers belonging to the genus "Japanese cypress" or "Japanese momi fir", which consists in the extraction of needles with organic solvents, preferably from a number of halogenated hydrocarbons, ethers, esters and ketones, followed by isolation of the target product by known hydrolysis methods , chromatography, fractional dissolution, fractional precipitation and molecular distillation [Japanese application No. 60-109536]. The disadvantages of this method are the use of needles, separated from the shoots, and the non-selectivity of the extraction process, in which the entire complex of soluble substances is immediately extracted, which complicates the further isolation and purification of polyprenols.

Closest to the invention is a method for producing a mixture of polyprenols by sequential extraction with liquefied carbon dioxide and a hydrocarbon solvent [RF patent No. 2053992, IPC ⁶ C 07 C 33/02, 29/00, publ. 02/10/96, BI No. 4], while polyprenol acetates are isolated from the hydrocarbon extract by known methods of hydrolysis, chromatography.

The disadvantage of this method is the non-selectivity of the process

extraction with a hydrocarbon solvent, which complicates the further isolation and purification of polyprenols. Hydrocarbon extract includes, in addition to polyprenol acetates, carotenoids, flavonoids, chlorophylls, resin acids, waxes, hydrocarbons, etc.

The objective of the invention is to provide a selective method for producing polyprenols from green wood fir, combined with the selective extraction of components of fir oil.

The technical result consists in the selective and sufficiently complete extraction of the target product from raw materials and is achieved by the fact that all essential oil components (monoterpenes, diterpenes, bornyl acetate, etc.) are selectively removed by extraction with dried oil and chopped wood greenery under subcritical conditions, then liquefied carbon dioxide is extracted, then acetates are extracted polyprenols with carbon dioxide in a supercritical state and polyprenols are isolated from the obtained extract by known methods, including hydrolysis and chromatography.

Extraction under subcritical conditions is carried out at a temperature of less than 31.1 ° C and a pressure of less than 72.5 atm.

Extraction under supercritical conditions is carried out at a temperature above 31.1 ° C and a pressure above 72.5 atm.

Extraction of carbon dioxide in a supercritical state provides selective and fairly complete extraction of the target product from raw materials, while the extractants recommended in RF patent No. 2053992 lead to the transfer of a large number of concomitant substances, such as carotenoids, chlorophylls, resin acids, waxes, hydrocarbons, etc. into the solution.

To obtain polyprenols, woody greens of the most common species of fir Abies sibirica Ledb in Russia can be used. and Abits nephroiepis Maxim.

A method with the claimed distinguishing features in the analysis of patent and scientific literature is not found.

The method of isolation of polyprenols is as follows. Crushed to a particle size of not more than 5 mm and dried to a moisture content of not more than 20-25%, wood fir greenery is exhaustively extracted with liquid CO ₂ at a temperature of 20-25 ° C and a pressure of 64 ± 4 atm (sufficient extraction time is 3 hours) in a flow extractor. From the extract was removed and CO ₂ is obtained extract liquid of pine oil components for household (TU 10-04-06-87-87) not containing polyprenols acetates. Spent green wood in the same installation is extracted with carbon dioxide in a supercritical state (at a temperature above the critical temperature of 31.1 ° C and a pressure above the critical pressure of 72.5) for 2 hours. After removal of carbon dioxide, a solution of polyprenol acetate concentrate is obtained, which is hydrolyzed by boiling in an aqueous-ethanolic alkali solution. The target product is isolated by chromatography of an unsaponifiable residue on silica gel using a mixture of a hydrocarbon solvent and ethyl acetate (93: 7 by volume) as eluent. The yield of polyprenols with a purity of 90-95% leaves 0.6-0.7% by weight of the initial woody green.

Subcritical liquid CO ₂ extracts only pine oil components (monoterpenes, bornylacetate), the desired product is extracted with supercritical CO _2, and not a hydrocarbon solvent, the use of which in these conditions avoids chlorophyll extraction, resin acids and other more polar associated components of wood greens impeding further purification of polyprenols.

The product obtained under the conditions of the proposed method has the form of a pale yellow mobile oil, insoluble in water, methanol, miscible with hexane, acetone and other organic solvents.

Example 1. Dried and crushed to particles of not more than 5 mm wood green Siberian fir (25 kg) is extracted in a flow extractor with liquefied carbon dioxide at a temperature of 20 ° C and a pressure of 64 atm for 3 hours (subcritical state). After separating the extract, the spent woody greens, without removing from the extractor, are additionally extracted with liquefied carbon dioxide at a temperature of 35 ° C and a pressure of 80 atm for 2 hours (supercritical state). To the resulting substance (15.8 g) add 200 ml of a 15% alcohol solution of sodium hydroxide and 20 ml of distilled water. After heating the mixture for 1 h with light boiling (70-80 ° C), it is cooled to room temperature, diluted with 0.3 l of distilled water and 200 ml of a mixture of petroleum ether and ethyl acetate (1: 1) are added. After thorough mixing and delamination, the lower aqueous alkaline layer is drained. The top layer was washed with distilled water (100 ml), dried with anhydrous sodium sulfate and evaporated to dryness. The obtained extract (9.3 g) is chromatographed on 0.5 kg of KSK silica gel (grain size 0.14-0.30 mm), eluting successively with mixtures of petroleum ether with ethyl acetate 98: 2 and 93: 7. The expected product is obtained by evaporation to dryness of the second eluate. Yield 8.2 g (0.6% by weight of the initial woody green). The purity of the product is not less than 95% of the spectrum of proton magnetic resonance (PMR).

Example 2. All operations are carried out as in example 1, but using hexane instead of petroleum ether. Yield 8.0 g. Purity no less than 95% according to the PMR spectrum.

The product obtained in examples 1 and 2 has the form of a pale yellow mobile oil, the PMR spectrum of which (in a CDCL solution) is fully consistent with the literature, and the HPLC chromatogram contains a set of peaks typical of polyprenols that correspond to individual isoprenologists from C50 to C100 with a relative content, traces, 0.1, 0.5, 1.1, 2.9, 13.2, 38.2, 26.9, 68, 1, 2, 0.5, and 0.2, respectively. HPLC analysis conditions: Milichrom microcolumn liquid chromatograph, 6.3 × 0.2 cm column, filled with Nucleosil C-18100-5 sorbent, eluent — methanol-hexane mixture (7: 3), UV detection.

Thus, the proposed method for producing polyprenols allows one to selectively, with high yield and purity, obtain polyprenes that can be used for the synthesis of dolichols, important animal and human cellular bioregulators.

Claims (1)

A method of producing polyprenols from fir green wood, including extraction of dried and crushed raw materials with liquefied carbon dioxide, followed by purification of the target product, characterized in that the raw materials are extracted in two stages: first, fir wood crushed to particles no more than 5 mm is extracted with liquefied carbon dioxide for 3 h in subcritical conditions at a temperature of less than 31.1 ° C and a pressure of less than 72.5 atm with the removal of components of fir oil, and then in the second stage the spent wood greens are extracted with liquefied carbon dioxide for 2 hours under supercritical conditions at a temperature above 31.1 ° C and a pressure above 72.5 atm.