JP2002080493A - Method for purifying sterols - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems that in a separation and purification of a sterol, a conventional method using a batch type crystallization apparatus has a difficulty in an increase of a treatment amount per time, and in order to reach a specified level of qualities such as purity, etc., repeated operations of crystallization are often required, and then the operation are complicated and a recovery yield is reduced. SOLUTION: An organic solvent containing a sterol is continuously supplied to a column type crystallization apparatus equipped with a cooling part at the upper part from the lower part of the apparatus. Cooling and crystallization are carried out at the upper cooling part. The organic solvent is brought into contact with a precipitating crystal in a countercurrent flow and dissolution and recrystallization of crystal are repeated to purify the crystal. The crystal precipitated at the lower part of the apparatus is separated and recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for purifying sterols. More specifically, the present invention relates to a method for obtaining sterols such as cholesterol, sitosterol, and ergosterol as high-purity crystals. These sterols are compounds useful as intermediates such as vitamin D and pharmaceuticals.

[0002]

2. Description of the Related Art Production of useful substances using bacteria, biological cells, and enzymes is widely performed on an industrial scale. However, the produced useful substances, so-called bioproducts, are sensitive to environmental changes such as temperature, and may be heated. In many cases, conventional separation and purification methods, such as evaporation, cannot be applied. As a method for purifying and separating such a substance, a crystallization method in which the substance is crystallized under relatively mild conditions and separated by solid-liquid separation is effective. cholesterol,
Conventionally, sterols such as sitosterol and ergosterol have been extracted from animals, plants, or yeasts using an organic solvent, and recovered from the extract by cooling crystallization.

[0003]

However, it has been difficult to increase the throughput per time in the method using the conventional batch crystallization apparatus. In addition, in order to reach a desired level of quality such as purity, it is necessary to repeatedly perform crystallization in some cases, in addition to complicated operations,
There has been a problem that a loss occurs in the recovery of the target material and the recovery rate is reduced.

[0004] In view of the above problems, the present invention provides a purification and isolation method capable of easily obtaining sterols with a large throughput per hour and obtaining high-purity crystals in high yield. .

[0005]

According to the present invention, an organic solvent containing sterols is continuously supplied from a lower part of a tower type crystallizer provided with a cooling part on an upper part, and crystallized in an upper cooling part. Dissolve crystals by countercurrent contact with settling crystals-
This is a purification method in which crystals are purified by repeating recrystallization, and crystals settled at the lower part of the apparatus are separated and recovered.

In the method of the present invention, a known solid-liquid separation technique can be used for separation and recovery of crystals, and sterols can be easily recovered. The liquid after the sterol crystals have been separated can be returned to the upstream of the tower crystallizer, that is, to the supply line side, to increase the recovery rate.
On the other hand, the sterols are removed and the sterols can be further recovered by connecting a plurality of the devices in series with respect to the liquid flowing out from the upper portion of the device, and the loss can be reduced.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

FIG. 1 schematically shows a tower type crystallizer used in the present invention. The organic solvent containing sterols is supplied from the nozzle 1 at the bottom of the tower. The supplied liquid is cooled when passing through the cooling unit 2 provided at the top of the tower, and sterols are precipitated.
Settles. In addition, the cooling unit may be provided with a stirrer with a scraping plate as needed in order to prevent the attachment of crystals to the wall surface of the cooling unit.

The crystals generated in the cooling section are brought into countercurrent contact with the feed liquid when they settle down in the column, are repeatedly dissolved and recrystallized, are purified, and then settle at the lower part of the apparatus. The crystals are discharged from the nozzle 3 as a slurry, and the crystals are collected by the solid-liquid separator 4. The liquid after the separation is returned to the supply line side.

On the other hand, the liquid from which the sterols have been removed is discharged from the upper nozzle 5. When the recovery rate is further increased by connecting a plurality of the apparatuses of the present invention in series, the liquid discharged from this portion is supplied to the second column type crystallizer. In addition, it is also possible to obtain the same effect as disposing a plurality of devices in series by dividing one device into a plurality of sections and cooling it to a lower temperature in the upper part.

In the present invention, in order to increase the degree of purification when the crystals settle in the column, the organic solvent used is an aliphatic hydrocarbon having a specific gravity of 0.9 or less at room temperature from the viewpoint of the sedimentation of the crystals, water-soluble. Preferably, the alcohol is selected from the group consisting of alcoholic alcohols and mixtures thereof. Specifically, hexane, heptane, octane, methyl alcohol, ethyl alcohol,
Examples thereof include isopropyl alcohol and a mixture thereof, and hexane is more preferable.

The sterols used in the present invention include cholesterol, desmosterol, 7-dehydrocholesterol, α-sitosterol, β-sitosterol,
Dihydro-β-sitosterol, γ-sitosterol,
Ergosterol, 22-dihydroergosterol and the like are preferable, and cholesterol, β-sitosterol and ergosterol are preferable.

The concentration of the sterol solution to be supplied to the apparatus cannot be specified unconditionally depending on the type of sterol and the solvent used. For example, when hexane is used as the solvent, ergosterol is usually 0.5 to 20 g / L, preferably 0.5 to 20 g / L. Is 2
-10 g / L, and usually 1-50 for cholesterol.
g / L, preferably 10 to 40 g / L.

The supply rate of the sterol solution may be appropriately determined according to the capacity of the apparatus and the residence time. If the residence time is too short, the precipitated crystals will not sediment well, and if it is too long, the equipment will be too large. The appropriate average residence time in the present invention is about 10 minutes to 5 hours, preferably about 30 minutes to 2 hours.

[0015]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to such examples.

(Example 1) An ergosterol hexane solution having a temperature of 40 ° C. and a concentration of 4 g / L was prepared with an inner diameter of 30 mm and a height of 4 g / L.
The product was continuously supplied to a 50 mm column type crystallizer to recover ergosterol. The operation of the crystallizer was carried out at a temperature at the outlet at the top of the tower of 10 ° C., a stirring rotation speed of 20 rpm, a liquid supply speed of 10 ml / min, and an average residence time of 30 minutes.
After continuous operation for 1 hour and 20 minutes (liquid sending amount: 800 ml), the concentration at the liquid outlet was measured and found to be 2 g / L.
It was found that 0% of ergosterol was recovered. The recovered ergosterol became white crystals with respect to the pale yellow color at the time of preparation, and its purity was measured by HPLC to find that it was 99.1% by the area percentage method. HPLC measurement conditions Column: Nacalai Tesque COSMOSIL 5C
18-MS 250 mm x 4.6 mm D. Column temperature: 35 ° C. Mobile phase: methanol / hexane = 90/10 (volume ratio) Pumping rate: 1.0 ml / min

Example 2 Temperature 40 ° C., Concentration 10 g / L
Was continuously supplied to the same apparatus as in Example 1 to recover cholesterol. The operation of the crystallization apparatus was carried out at a temperature of 5 ° C. at the top of the tower, a stirring rotation speed of 20 rpm (using a stirring blade with a scraping plate), a liquid supply speed of 6 ml / min, and an average residence time of 30 minutes. After continuous operation for 2 hours 30 minutes (liquid sending amount: 900 ml), the concentration at the liquid outlet was measured and found to be 5 g / L, and it was found that 50% cholesterol was recovered by the single-stage apparatus.

Comparative Example 1 Temperature 45 ° C., concentration 2.7 g /
L of ergosterol (mixed with hexane and isopropanol) was batch-cooled and crystallized at a cooling rate of 0.2 ° C./min using a jacketed stirring tank having an inner volume of 500 ml to recover ergosterol. 66% recovery
However, a series of operations including charging, crystallization and filtration required about 5 hours.

Comparative Example 2 A temperature of 45 ° C. and a concentration of 2.7 g /
L of ergosterol (hexane / isopropanol mixture) solution was batch-cooled and crystallized at a cooling rate of 0.5 ° C./min using a jacketed stirring tank having an inner volume of 500 ml to recover ergosterol. Charge, crystallization,
The time required for the filtration and the series of operations was about 3 hours. However, the crystal adhered to the tank wall and the stirring blade was severe, and the recovery rate was reduced to 20%.

[0020]

According to the present invention, sterols can be easily and industrially advantageously purified with little loss.

[Brief description of the drawings]

FIG. 1 shows an example of a tower type crystallizer used in the present invention.

Claims (5)

[Claims] 1. An organic solvent containing sterols is continuously supplied from a lower part of a tower type crystallizer provided with a cooling part on an upper part, and crystallized and precipitated in an upper cooling part. A method for purifying sterols, comprising refining crystals by repeating dissolution-recrystallization of crystals by bringing them into countercurrent contact, and separating and recovering crystals settled at the lower part of the apparatus. 2. The method according to claim 1, wherein the liquid after the sterol crystals have been separated and recovered is returned to the supply side of the crystallizer.
The described method. 3. The method according to claim 1, wherein the organic solvent is an aliphatic hydrocarbon having a specific gravity of 0.9 or less at room temperature, a water-soluble alcohol, or a mixture thereof. 4. The method according to claim 1, wherein the organic solvent is hexane, heptane, octane, methyl alcohol, ethyl alcohol, isopropyl alcohol, or a mixture thereof. 5. The sterol is cholesterol, sitosterol, or ergosterol.
The method according to any of the above.