JP7727960B2 - High-purity shell ginger extract and method for producing the same - Google Patents

Description

The present invention relates to a highly pure shell ginger extract and a method for producing the same.

Alpinia zerumbet leaf extract is known as one of the functional ingredients in functional food products. The functionality of Alpinia zerumbet leaf extract is said to be its skin-beautifying effect, helping to moisturize the skin of those who tend to have dry skin.

The index components in Alpinia zerumbet leaf extract are two types of α-pyrones: dihydro-5,6-dehydrokawain and 5,6-dehydrokawain. Because Alpinia zerumbet leaf extract contains these α-pyrones, it is believed to have skin-beautifying effects through its ability to promote fibroblast proliferation, collagen production, and inhibit collagen-degrading enzyme activity.

Known methods for producing shell ginger leaf extract include an ethanol extraction process in which shell ginger leaves are added to aqueous ethanol, and a hot water extraction process in which shell ginger leaves are added to water and heated (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2002-302453

However, the method of subjecting shell ginger leaves to ethanol extraction or hot water extraction as described in Patent Document 1 has the problem that the resulting extract contains sugars, flavonoids, and the like in addition to α-pyrones, resulting in low purity of the α-pyrones.

The present invention therefore aims to provide a method for producing shell ginger extract with a higher purity of α-pyrones than the method described in Patent Document 1.

After extensive research to solve the above-mentioned problems, the inventors focused on the state of the shell ginger used in the extraction process and further processing after the extraction process. Through repeated trial and error, including using shell ginger in various states and applying various processes to the extracted material, they surprisingly discovered that a shell ginger extract containing α-pyrones at a high purity can be obtained by performing a solvent extraction process using dried shell ginger, and then subjecting the resulting solvent-extracted material to a water treatment and an alkali treatment. As a result, the inventors succeeded in creating a method for producing a shell ginger extract containing α-pyrones at a high purity from shell ginger. The present invention was completed based on these findings and successful examples.

Therefore, according to the present invention, the following methods and shell ginger extracts are provided.
[1] A step of obtaining a shell ginger crude extract by subjecting a dried shell ginger product to an extraction treatment using a dehydrokawain-soluble solvent;
A method for producing a shell ginger extract, comprising the steps of subjecting a crude shell ginger extract to a water treatment and an alkali treatment to obtain an shell ginger extract.
[2] A step of obtaining a shell ginger crude extract by subjecting the shell ginger dried product to an extraction treatment using a dehydrokawain-soluble solvent;
A method for producing a shell ginger extract, comprising the steps of subjecting a crude shell ginger extract to a water treatment, an alkali treatment and salting out to obtain a shell ginger extract.
[3] The method according to any one of [1] to [2], wherein the crude extract of the moonwort is a crude extract of the moonwort obtained by subjecting the extract obtained by the extraction process to a solid-liquid separation process and/or a concentration process.
[4] The method according to any one of [2] to [3], wherein the salting out is performed using at least one sugar selected from the group consisting of glucose, sucrose, and maltose.
[5] The method according to any one of [1] to [4], wherein the dehydrokawain-soluble solvent is 30% (v/v) to 90% (v/v) aqueous ethanol.
[6] The method according to any one of [1] to [5], wherein the alkali treatment is an alkali treatment using sodium hydroxide at a final concentration of 0.5% (w/v) to 6% (w/v).
[7] The method according to any one of [1] to [6], wherein the shell ginger extract has a total content of dihydro-5,6-dehydrokawain and 5,6-dehydrokawain of 80% (w/w) or more.
[8] The method according to any one of [1] to [7], wherein the shell ginger extract has a dihydro-5,6-dehydrokawain content of 70% (w/w) or more and/or a 5,6-dehydrokawain content of 10% (w/w) or more.
[9] The method according to any one of [1] to [8], wherein the shell ginger extract is a solid shell ginger extract.
[10] A shell ginger extract, in which the total content of dihydro-5,6-dehydrokawain and 5,6-dehydrokawain is 80% (w/w) or more, and the dihydro-5,6-dehydrokawain and 5,6-dehydrokawain are derived from shell ginger.
[11] The shell ginger extract described in [10], wherein the shell ginger extract has a dihydro-5,6-dehydrokawain content of 80% (w/w) or more and/or a 5,6-dehydrokawain content of 10% (w/w) or more.

According to a method of one aspect of the present invention, it is possible to produce a shell ginger extract containing highly purified α-pyrones, such as dihydro-5,6-dehydrokawain and 5,6-dehydrokawain, using shell ginger as a raw material. Furthermore, because the processing procedures employed in the method of the present invention are simple and safe, it is possible to produce shell ginger extract in large quantities on an industrial scale using the method of one aspect of the present invention. Therefore, the method of one aspect of the present invention is a method for producing a highly pure shell ginger extract that is industrially practical, rapid, safe, and economical.

Since the shell ginger extract obtained by the method of one embodiment of the present invention can be in a solid form, it can be processed into a variety of dosage forms and added to various foods, beverages, and cosmetics. Furthermore, because it has excellent shelf life, it can be widely distributed.

FIG. 1 is a flow chart showing an outline of the method for producing a high-purity shell ginger extract using shell ginger flowers as a raw material in Example 1, as described in the examples below. FIG. 2 is a flow chart showing an outline of the method for producing a high-purity shell ginger extract using shell ginger flowers as a raw material in Example 2, as described in the examples below. FIG. 3 is a flow chart showing an outline of the method for producing a high-purity shell ginger extract using shell ginger flowers as a raw material in Example 3, as described in the examples below. FIG. 4 is a flow chart showing an outline of a method for producing a high-purity shell ginger extract using shell ginger leaves as a raw material according to Example 4, as described in the examples below.

Each aspect of the present invention is described in detail below, but the present invention can take various forms as long as it achieves its objectives.

Unless otherwise specified, the terms used in this specification are used in the sense commonly used by those skilled in the food, cosmetics, and other fields, and should not be construed as having an unduly restrictive meaning. Furthermore, the speculations and theories expressed in this specification are based on the inventors' knowledge and experience to date, and therefore the present invention is not limited solely to such speculations and theories.

The term "and/or" means any one or any or all combinations of two or more of the associated listed items.
"Content" is synonymous with concentration and amount used (amount added), and refers to the ratio of the amount of a component to the total amount of shell ginger extract. However, the total amount of component content does not exceed 100%. "Purity" is also used synonymously with content. In other words, a highly pure component refers to a component that occupies a high proportion in the shell ginger extract.
The unit "vol%" is synonymous with "% (v/v)" and "volume %". The unit "wt%" is synonymous with "% (w/w)" and "mass %". The unit "% (w/v)" is synonymous with "mass volume %".
The "to" in a numerical range means a range that includes the preceding and following numerical values, for example, "0% to 100%" means a range that is equal to or greater than 0% and equal to or less than 100%. "More than" and "less than" mean a lower limit and an upper limit, respectively, that are exclusive of the preceding numerical value, for example, "more than 1" means a numerical value greater than 1, and "less than 100" means a numerical value less than 100.
"Comprising" means that elements other than those explicitly stated as being included can be added (same meaning as "comprising at least"), but also encompasses "consisting of" and "consisting essentially of." That is, "comprising" can mean including the explicitly stated elements and any one or more elements, consisting of the explicitly stated elements, or consisting essentially of the explicitly stated elements. Elements include limitations such as ingredients, steps, conditions, and parameters.

The number of digits in an integer value matches the number of significant digits. For example, 1 has one significant digit, and 10 has two significant digits. Also, the number of digits after the decimal point matches the number of significant digits in a decimal value. For example, 0.1 has one significant digit, and 0.10 has two significant digits.

In this specification, dihydro-5,6-dehydrokawain may be referred to as "DDK" and 5,6-dehydrokawain may be referred to as "DK." Furthermore, "dehydrokawain" is a general term for either DDK or DK, or a combination of DDK and DK. DDK and DK are compounds having the following structures:

One embodiment of the present invention is a method for producing a shell ginger extract containing highly purified dehydrokawain. The method of one embodiment of the present invention is characterized by subjecting the shell ginger raw material, shell ginger, to solvent extraction, water addition, and alkali treatment, or solvent extraction, water addition, alkali treatment, and salting out, thereby obtaining a shell ginger extract containing dehydrokawain.

A first embodiment of the method of the present invention comprises the following steps (1) and (2):
(1) A step of subjecting a dried shell ginger plant to an extraction treatment using a dehydrokawain-soluble solvent to obtain a shell ginger crude extract; (2) A step of subjecting the shell ginger crude extract to a water treatment and an alkali treatment to obtain an shell ginger extract.

The second embodiment of the method of the present invention comprises the following steps (1) and (2)'.
(1) A step of subjecting a dried shell ginger plant to an extraction treatment using a dehydrokawain-soluble solvent to obtain a shell ginger crude extract. (2)' A step of subjecting the shell ginger crude extract to a water treatment, an alkali treatment and salting-out to obtain a shell ginger extract.

In step (1), dried shell ginger is subjected to an extraction process using a dehydrokawain-soluble solvent to obtain a crude shell ginger extract.

Shell ginger ( Alpinia zerumbet ), also known as getto, is an evergreen perennial plant known to grow wild from the southern tip of Kyushu to Okinawa Prefecture, from Taiwan to southern China, Southeast Asia, and India. Shell ginger is known to promote fibroblast proliferation, promote collagen production, and inhibit collagen-degrading enzyme activity, and is consumed in the hope of achieving skin-beautifying effects through these. Furthermore, shell ginger is a natural plant that has a long history of human consumption and is highly safe.

The part of the shell ginger used is not particularly limited as long as it contains dehydrokawain, and examples include leaves, flowers, roots, stems, fruits, and seeds, but leaves, flowers, and roots, which contain a large amount of dehydrokawain, are preferred. The shell ginger may be a single part such as leaves, flowers, or roots, or a combination of two or more of these parts.

When shell ginger is used in its freshly harvested state, the efficiency of the extraction process tends to decrease. Therefore, the shell ginger is dried and used as a dried shell ginger. The drying process is not particularly limited, and examples include drying the shell ginger so that its mass after drying (dry mass) is approximately 1/100 to 9/10 of its mass before drying (wet mass). The drying process may be carried out by any method known to those skilled in the art, such as hot air drying, vacuum drying, low-temperature vacuum drying, high-pressure steam drying, electromagnetic wave drying, freeze drying, or air drying. The moisture content of the dried shell ginger is not particularly limited, but is preferably 20% or less, and more preferably 10% or less.

From the perspective of increasing the contact area with the solvent and carrying out the extraction process efficiently, it is preferable that the shell ginger be in a shredded, crushed, pulverized, or ground state. There are no particular limitations on the method for shredding, crushing, pulverizing, or pulverizing the shell ginger, but examples include methods using a cutter, slicer, cutting machine, crusher, blender, mixer, mill, grinder, kneader, mortar, stone mill, etc.

When using roots, stems, seeds, etc. as the shell ginger, the dried shell ginger used in step (1) is preferably powdered shell ginger to improve the efficiency of the extraction process. When obtaining powdered shell ginger, the drying and crushing processes may be carried out simultaneously, or one process may be carried out first and then the other, but for ease of operation, it is preferable to carry out the drying process first and then the crushing process.

The dehydrokawain-soluble solvent is not particularly limited as long as it is capable of dissolving dehydrokawain. Examples include solvents that readily dissolve dehydrokawain, specifically water; lower alcohols such as methanol, ethanol, propanol, isopropanol, and butanol; lower esters such as ethyl acetate and methyl acetate; dimethyl sulfoxide, acetonitrile, acetone, hexane, glycerin, and propylene glycol. The dehydrokawain-soluble solvent may be one of these solvents alone or a combination of two or more of these solvents.

From the viewpoints of extraction efficiency, safety, and industrial feasibility, the dehydrokawain-soluble solvent is preferably water or a lower alcohol, more preferably water, ethanol, or methanol, even more preferably water and ethanol, and even more preferably aqueous ethanol, which is a mixed solvent of water and ethanol.

When aqueous ethanol is used as the dehydrokawain-dissolving solvent, the ethanol content is preferably 20 vol% to 100 vol%, and from the standpoints of good extraction efficiency, safety, and industrial feasibility, 30 vol% to 90 vol% is more preferred, 40 vol% to 80 vol% is even more preferred, and 50 vol% to 70 vol% is even more preferred. However, if the ethanol content in the aqueous ethanol is less than 20 vol%, it may be difficult to efficiently extract dehydrokawain.

Extraction conditions are not particularly limited as long as they are suitable for dissolving the dehydrokawain in the dried shell ginger plant in the solvent. The type and amount of dehydrokawain-soluble solvent used can be appropriately determined depending on the state of the dried shell ginger plant (e.g., moisture content) and the amount used. For example, the dried shell ginger plant may be immersed for a predetermined period of time in a dehydrokawain-soluble solvent that is 1 to 20 times, preferably 2 to 15 times, and more preferably 3 to 10 times the volume of the dried shell ginger plant. During this extraction process, stirring, heating, etc. may be performed as necessary to increase extraction efficiency.

Specific conditions for the extraction process include, but are not limited to, placing dried shell ginger and 50% to 70% aqueous ethanol in a container at a volume 3 to 10 times the volume of the dried shell ginger, and leaving the mixture to stand or stir at 10°C to 40°C, preferably room temperature (20°C to 30°C), for several hours to several days, preferably 12 hours to 10 days.

By subjecting the dried shell ginger to the extraction process described above, an extract and an extraction residue can be obtained. By performing a solid-liquid separation process after the extraction process, the extract and the extraction residue can be separated efficiently. There are no particular limitations on the solid-liquid separation method, but known solid-liquid separation methods such as filtration and centrifugation can be used.

When an organic solvent is used as the dehydrokawain-soluble solvent, it is preferable to subject the extract to a concentration treatment in order to volatilize the organic solvent. The concentration treatment is not particularly limited as long as it is a commonly known treatment that removes the organic solvent and further reduces the volume of the liquid, and examples include placing the extract under reduced pressure at room temperature, placing it under a low-temperature vacuum, heating, and freeze-drying. The degree of concentration is not particularly limited, but it is sufficient to reduce the volume to, for example, about 1/1,000 to 1/10, preferably 1/100 to 1/10, and the liquid components may be volatilized until the extract is in a solid, dry state.

The extraction process may be performed once, but to increase the recovery rate of DDK and/or DK, it is preferable to perform the extraction process twice or more, and from the standpoint of workload and economy, it is more preferable to perform the extraction process twice. For example, step (1) may be performed by subjecting the dried shell ginger to a first extraction process to obtain a first extract and a first extraction residue, and then subjecting the obtained first extraction residue to a second extraction process to obtain a second extract and a second extraction residue.

When the extraction process is performed two or more times, each extraction process may be performed under the same conditions or under different conditions. The extracts obtained from each extraction process can be combined and used as a single shell ginger crude extract in the next step. When the extracts are subjected to solid-liquid separation and/or concentration, each extract may be subjected to solid-liquid separation and/or concentration, or the combined extracts may be subjected to solid-liquid separation and/or concentration.

As described above, a crude shell ginger extract is obtained by subjecting the dried shell ginger to extraction, preferably by subjecting it to two or more extraction processes, and more preferably by subjecting each extract to solid-liquid separation and concentration after two extraction processes and combining them.

The content of dehydrokawain in the shell ginger crude extract is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, and even more preferably 2.0% by mass or more.

In step (2), the shell ginger extract obtained in step (1) is subjected to a water treatment and an alkali treatment to obtain a shell ginger extract. By subjecting the shell ginger crude extract to a water treatment and an alkali treatment, water-soluble components and impurities such as fatty acids in the shell ginger crude extract are removed, and a shell ginger extract containing a high concentration of dehydrokawain can be obtained as an insoluble matter (precipitate).

The conditions for the hydration treatment are not particularly limited, as long as water is added to the shell ginger crude extract. For example, the treatment can be carried out by contacting the shell ginger crude extract with 1 to 20 times the volume of water, preferably 2 to 15 times the volume of water, more preferably 4 to 10 times the volume of water, and even more preferably 6 to 8 times the volume of water relative to the volume of the shell ginger crude extract. The temperature and time for this treatment are not particularly limited, and may be, for example, 10 to 30°C for a period of several seconds to several minutes to several hours.

The alkali treatment is not particularly limited as long as it is carried out under conditions that decompose impurities in the shell ginger crude extract and allow dehydrokawain to precipitate as an insoluble component. For example, the alkali treatment can be carried out by stirring and/or leaving an aqueous solution containing the shell ginger crude extract and an alkaline component at 10°C to 30°C, preferably at room temperature, for several hours to several days.

The alkaline component used in the alkaline treatment is not particularly limited as long as it decomposes impurities in the shell ginger crude extract and does not dissolve dehydrokawain. Examples include sodium hydroxide, potassium hydroxide, and calcium hydroxide, but sodium hydroxide is preferred as it is a strong alkali and is economical.

The amount of alkaline component used in the alkaline treatment is not particularly limited as long as it is an amount that can precipitate dehydrokawain. For example, if the alkaline component is sodium hydroxide, the amount is such that the final concentration is 0.1% (w/v) to 10% (w/v), preferably 0.5% (w/v) to 8% (w/v), and more preferably 0.5% (w/v) to 6% (w/v). Using pH as an indicator, the amount of alkaline component used in the alkaline treatment is preferably an amount that will bring the pH to the alkaline side, preferably 12 to 14, and more preferably around 14.

In step (2), the hydration treatment and alkali treatment may be carried out simultaneously by using an aqueous alkaline solution. For example, step (2) can be carried out by adding shell ginger crude extract to an aqueous solution of sodium hydroxide dissolved in water, adjusting the volume of water to 5 to 10 times the volume of the shell ginger crude extract, stirring at 10 to 30°C, preferably at room temperature, for several hours to several days, preferably 1 to 24 hours, and then leaving to stand for several hours to several days, preferably 10 hours to 7 days.

In step (2)', in addition to the water treatment and alkali treatment, salting out is carried out. Salting out allows for efficient precipitation of dehydrokawain. There are no particular limitations on the conditions for salting out, as long as they allow for precipitation of dehydrokawain. For example, salting out can be carried out by stirring and/or allowing an aqueous solution containing shell ginger crude extract and salts to stand at 10°C to 30°C, preferably at room temperature, for several hours to several days.

The salts used in the salting-out process are not particularly limited as long as they are water-soluble substances with a higher hydration capacity than dehydrokawain, but examples include organic salts and inorganic salts. From the standpoint of corrosiveness and safety, sugars such as glucose, sucrose, and maltose are preferred, with glucose being more preferred.

The amount of salt used in salting out is not particularly limited as long as it is an amount that allows dehydrokawain to precipitate as a solid. For example, if the salt is glucose, the amount should be such that the final concentration is 0.1% (w/v) to 10% (w/v), preferably 0.5% (w/v) to 5% (w/v), and more preferably 0.5% (w/v) to 2% (w/v).

In step (2)', the water treatment, alkali treatment, and salting-out may be carried out sequentially, or two or three of these treatments may be carried out simultaneously. For example, step (2)' can be carried out by adding the shell ginger crude extract to an aqueous solution of sodium hydroxide and salts in water, adjusting the volume of water to 5 to 10 times the volume of the shell ginger crude extract, stirring at 10°C to 30°C, preferably at room temperature, for several hours to several days, preferably 1 hour to 24 hours, and then leaving to stand for several hours to several days, preferably 10 hours to 7 days.

Steps (2) and (2)' can be performed once to obtain a shell ginger extract containing highly pure dehydrokawain, without the need for multiple steps, but they may also be performed multiple times. The shell ginger extract can be obtained as a precipitate in a solid form, specifically in powder form. The obtained aqueous solution containing the powdered shell ginger extract can be subjected to solid-liquid separation and/or drying, allowing the powdered shell ginger extract to be efficiently recovered. When using the shell ginger extract as a raw material for, for example, an oral composition or an external composition, it is preferable to wash it with water or the like.

The content of dehydrokawain in the shell ginger extract obtained by the method of one embodiment of the present invention is not particularly limited, but is preferably 70 wt% or more, more preferably 80 wt% or more, even more preferably 90 wt% or more, and even more preferably 95 wt% or more, based on the dry mass of the shell ginger extract. The recovery rate of dehydrokawain in the shell ginger extract is preferably 30% or more, more preferably 40% or more, even more preferably 80% or more, and even more preferably 90% or more, based on the dehydrokawain content in the shell ginger crude extract. The upper limits of these are not particularly limited, but are typically 100 wt% and 100%, respectively.

The DDK and DK content varies depending on the part of the shell ginger plant. When shell ginger flowers are used, shell ginger extract containing both DDK and DK is obtained, while when shell ginger leaves are used, shell ginger extract containing DDK tends to be obtained.

When shell ginger flowers are used, the DDK content in the shell ginger extract is, for example, preferably 60 wt% or more, more preferably 70 wt% or more, and even more preferably 80 wt% or more, based on the dry mass of the shell ginger extract. In this case, the DDK recovery rate in the shell ginger extract is, for example, preferably 30% or more, more preferably 40% or more, even more preferably 80% or more, and even more preferably 90% or more, relative to the DDK content in the shell ginger crude extract. There are no particular limitations on these upper limits, but they are typically 100 wt% and 100%, respectively.

When shell ginger flowers are used, the DK content in the shell ginger extract is, for example, preferably 5 wt% or more, more preferably 10 wt% or more, and even more preferably 12 wt% or more, based on the dry mass of the shell ginger extract. In this case, the DK recovery rate in the shell ginger extract is, for example, preferably 10% or more, more preferably 20% or more, even more preferably 40% or more, and even more preferably 60% or more, relative to the DK content in the shell ginger crude extract. While there are no particular limitations on these upper limits, they are typically 100 wt% and 100%, respectively.

When using shell ginger leaves, the DDK content in the shell ginger extract is, for example, preferably 60 wt% or more, more preferably 70 wt% or more, even more preferably 80 wt% or more, and even more preferably 90 wt% or more, based on the dry mass of the shell ginger extract. In this case, the DDK recovery rate in the shell ginger extract is, for example, preferably 30% or more, more preferably 40% or more, even more preferably 80% or more, and even more preferably 90% or more, relative to the DDK content in the shell ginger crude extract. While these upper limits are not particularly limited, they are typically 100 wt% and 100%, respectively. In this case, the DK content in the shell ginger extract is 1 wt% or less.

The dehydrokawain contained in the shell ginger extract can be confirmed and quantified using high-performance liquid chromatography (HPLC) as described in the Examples below.

In one aspect of the method of the present invention, various steps or operations can be added before, after, or between the steps described above, as long as the object of the present invention can be solved.

As a specific embodiment of the present invention, a method for producing a shell ginger extract containing dehydrokawain using dried shell ginger flowers as a raw material is described below, but the method of one embodiment of the present invention is not limited to the following.

Shell ginger flowers harvested when they are in bloom (May to July) are subjected to low-temperature vacuum drying until the moisture content is 10% or less. A predetermined amount of dried shell ginger flowers is added to 50% to 70% aqueous ethanol, which is 3 to 10 times the volume of the dried shell ginger flowers, and the mixture is left to stand at room temperature for 12 hours to 10 days to carry out an extraction process. The resulting extract is filtered to remove the shell ginger residue, and the resulting filtrate is then concentrated under reduced pressure to obtain a first shell ginger crude extract. The shell ginger residue is then subjected to a similar extraction process to obtain a second shell ginger crude extract. The first shell ginger crude extract and the second shell ginger crude extract are mixed and used in the following process.

Next, an aqueous solution of sodium hydroxide and glucose is added to the obtained shell ginger crude extract, and water is added to a volume 5 to 10 times that of the shell ginger crude extract. The final sodium hydroxide concentration of the obtained aqueous solution is 0.5% (w/v) to 6% (w/v), and the final glucose concentration is 0.5% (w/v) to 2% (w/v). The obtained aqueous solution is then stirred at room temperature for 1 to 24 hours, and then allowed to stand for 10 hours to 5 days to obtain shell ginger extract as a precipitate. The obtained shell ginger extract is subjected to filtration and freeze-drying to obtain a powdered shell ginger extract. The dehydrokawain content of the obtained shell ginger extract can be 90 wt% or more based on the dry weight of the shell ginger extract.

The shell ginger extract produced by the method of one aspect of the present invention can be included in the present invention as another aspect. The shell ginger extract of the present invention is characterized in that the total content of DDK and/or DK is a predetermined amount, and the DDK and/or DK contained therein is derived from the shell ginger, which is the raw material.

In one embodiment of the shell ginger extract of the present invention, the total content of DDK and DK is, for example, 80 wt% or more, preferably 90 wt% or more, and more preferably 95 wt% or more. There is no particular upper limit to this content, but it is typically 100 wt%.

In one embodiment of the shell ginger extract of the present invention, the DDK content is preferably 70 wt% or more, more preferably 80 wt% or more, and even more preferably 90 wt% or more, based on the dry mass of the shell ginger extract. In one embodiment of the shell ginger extract of the present invention, the DK content is preferably 5 wt% or more, more preferably 10 wt% or more, and even more preferably 12 wt% or more, based on the dry mass of the shell ginger extract. However, although it is preferable that the shell ginger extract of one embodiment of the present invention contains both DDK and DK, it is sufficient if it contains either DDK or DK.

The DDK and DK contained in the shell ginger extract of one embodiment of the present invention are characterized in that both are derived from the shell ginger, which is the raw material. In other words, the shell ginger extract of one embodiment of the present invention is characterized in that it does not contain DDK or DK obtained by extraction or synthesis of natural products other than shell ginger.

The uses of the shell ginger extract of one embodiment of the present invention are not particularly limited, and for example, it can be used as an ingredient in various compositions, such as oral compositions such as foods and beverages and pharmaceuticals, and topical compositions such as cosmetics, or as the composition itself, in anticipation of the pharmacological effects of dehydrokawain.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples, and the present invention can take various forms as long as the object of the present invention is solved.

[Quantitative determination of shell ginger extract]
The contents (mg) of dihydro-5,6-dehydrokawain (DDK) and 5,6-dehydrokawain (DK) were measured by HPLC using a COSMOSIL 5C18-AR-2 column as the column and MeOH:H ₂ O=60:40 to 100:0 as the mobile phase at a flow rate of 1 ml/min, with the calibration curve method being used to measure peaks with retention times of approximately 12 minutes for DDK at a measurement wavelength of 278.0 nm and approximately 17 minutes for DK at a measurement wavelength of 318 nm.

[Example 1. Production of high-purity shell ginger extract using shell ginger flowers as raw material (1)]
As Example 1, a flow diagram showing an outline of a method for producing a high-purity shell ginger extract using shell ginger flowers as a raw material, carried out on a 100 g scale using a system of 4% (w/v) sodium hydroxide and 1% (w/v) glucose, is shown in Figure 1.

Alpinia sieboldii flowers were subjected to low-temperature vacuum drying at 40°C for 5 hours to obtain dried flowers (moisture content 3%-8%). 100.0 g of dried flowers were placed in 500 mL of 60% (v/v) aqueous ethanol and subjected to an ethanol extraction process by leaving the mixture at room temperature for 1 day. The extract was then filtered using a filter (pore size 5 μm) to obtain 224.1 g of filtrate (1) and 325.9 g of residue (1). The entire amount of filtrate (1) was subjected to vacuum concentration to obtain 7 g of crude extract (1) as the first extract. The DDK content in crude extract (1) was 448.6 mg, and the DK content was 120.3 mg.

Furthermore, the filtration residue (1) was placed in 500 mL of 60% (v/v) aqueous ethanol and subjected to an ethanol extraction process by leaving the mixture at room temperature for one day. It was then filtered using a filter (pore size: 5 μm) to obtain 467.1 g of filtrate (2). The entire amount of filtrate (2) was subjected to vacuum concentration to obtain 6 g of crude extract (2) as a second extract. The DDK content in crude extract (2) was 375.5 mg, and the DK content was 105.4 mg.

An aqueous solution containing 4.0 g of sodium hydroxide and 1.0 g of glucose was added to crude extract (1+2), which was a combination of crude extract (1) and crude extract (2). Water was then added to bring the total volume to 100 mL. The resulting solution (pH 14) was stirred (150 rpm) at room temperature for 5 hours, then left to stand for 19 hours for alkali treatment and salting out. It was then centrifuged (2600 x g, 4,000 rpm, 1 minute). The resulting precipitate was freeze-dried to yield 1,012.6 mg of shell ginger extract in powder form.

The resulting shell ginger extract contained 843.5 mg of DDK (purity 83.3%) and 155.3 mg of DK (purity 15.3%). Furthermore, based on the amounts of DDK and DK contained in the crude extract (1+2), the recovery rate of DDK in the shell ginger extract was 103%, and the recovery rate of DK was 70%.

[Example 2. Production of high-purity shell ginger extract using shell ginger flowers as raw material (2)]
As Example 2, a flow diagram showing an outline of a method for producing a high-purity shell ginger extract using shell ginger flowers as a raw material, carried out on a 38.0 kg scale using a system of 4% (w/v) sodium hydroxide and 1% (w/v) glucose, is shown in Figure 2.

Alpinia sieboldii flowers were subjected to low-temperature vacuum drying at 40°C for 5 hours to obtain dried flowers (moisture content 3%-8%). 38.0 kg of dried flowers were placed in 180 L of 60% (v/v) aqueous ethanol and subjected to an ethanol extraction process by leaving the mixture at room temperature for 7 days. The mixture was then filtered using a filter (pore size 20 μm) to obtain approximately 120 L of filtrate (1) and filtration residue (1). The entire filtrate (1) was subjected to low-temperature vacuum drying at 40°C for 5 hours to obtain crude extract (1) as the first extract. The DDK content in crude extract (1) was 200 g, and the DK content was 62 g.

Furthermore, the filtration residue (1) was placed in 180 L of 60% (v/v) aqueous ethanol and subjected to an ethanol extraction process by leaving it at room temperature for 7 days, followed by filtration using a filter (pore size 20 μm) to obtain approximately 150 L of filtrate (2). The entire amount of filtrate (2) was subjected to low-temperature vacuum drying at 40°C for 6 hours to obtain crude extract (2) as a second extract. The DDK content in crude extract (2) was 87 g, and the DK content was 27 g.

The total amounts of crude extract (1) and crude extract (2) were combined to form crude extract (1+2), which was then subjected to low-temperature vacuum drying.

An aqueous solution containing 1.5 kg of sodium hydroxide and 350 g of glucose was added to the extract (1+2), and water was added to bring the total volume to 38 L. The resulting solution (pH 14) was stirred (150 rpm) at room temperature for 15 hours, then left to stand for 3 days for alkali treatment, followed by centrifugation (2600 x g, 4,000 rpm, 10 minutes). The resulting precipitate was freeze-dried to yield 189.5 g of powdered shell ginger extract.

The resulting shell ginger extract contained 134.5 g of DDK (purity 71.0%) and 25.9 g of DK (purity 13.7%). Furthermore, based on the amounts of DDK and DK contained in the crude extract (1+2), the recovery rate of DDK in the shell ginger extract was 47%, and the recovery rate of DK was 29%.

[Example 3. Production of high-purity shell ginger extract using shell ginger flowers as raw material (3)]
As Example 3, a flow diagram showing an outline of a method for producing a high-purity shell ginger extract using shell ginger flowers as a raw material, carried out on a 100 g scale using 1% (w/v) sodium hydroxide and no glucose, is shown in Figure 3.

Alpinia zerumbet flowers were subjected to low-temperature vacuum drying at 40°C for 5 hours to obtain dried flowers (moisture content 3% to 8%). 100.0 g of the dried flowers were placed in 500 mL of 60% (v/v) aqueous ethanol and subjected to an ethanol extraction process by leaving the mixture at room temperature for 1 day. The mixture was then filtered using a filter (pore size 5 μm) to obtain filtrate (1) and filtration residue (1).

The filtration residue (1) was placed in 500 mL of 60% (v/v) aqueous ethanol and subjected to an ethanol extraction process by leaving the mixture at room temperature for one day. The filtrate (2) was then obtained by filtering the residue using a filter (pore size: 5 μm).

Filtrate (1) and filtrate (2) were combined to give 714.9 g of filtrate (1+2), which was then concentrated under reduced pressure to obtain 13 g of crude extract (1+2). The DDK content in crude extract (1+2) was 838.9 mg, and the DK content was 252.3 mg.

An aqueous solution containing 1.0 g of sodium hydroxide was added to the resulting crude extract (1+2), and water was added to bring the total volume to 100 mL. The resulting aqueous solution (pH 10) was stirred (150 rpm) at room temperature for 5 hours, then left to stand for 19 hours (an alkali treatment), and then centrifuged (2600 x g, 4,000 rpm, 1 minute). The resulting precipitate was freeze-dried to yield 1265.9 mg of powdered shell ginger extract.

The resulting shell ginger extract contained 939.7 mg of DDK (purity 74.2%) and 190.9 mg of DK (purity 15.1%). Furthermore, based on the amounts of DDK and DK contained in the crude extract (1+2), the recovery rate of DDK in the shell ginger extract was 112%, and the recovery rate of DK was 76%.

[Example 4. Production of high-purity shell ginger extract using shell ginger leaves as raw material]
As Example 4, a flow diagram showing an outline of a method for producing a high-purity shell ginger extract using shell ginger leaves as a raw material, carried out on a 100 g scale using a system of 4% (w/v) sodium hydroxide and 1% (w/v) glucose, is shown in Figure 4.

Alpinia ginseng leaves were subjected to a thermal drying process to obtain dried leaves. 100.0 g of dried leaves were placed in 600 mL of 60% (v/v) aqueous ethanol and left to stand at room temperature for 4 days for an ethanol extraction process. The extract was then filtered using a filter (pore size 5 μm) to obtain 282.7 g of filtrate (1) and 357.3 g of filtration residue (1). The entire amount of filtrate (1) was subjected to vacuum concentration to obtain crude extract (1) as the first extract. The crude extract (1) contained 227.5 mg of DDK, but DK was below the lower limit of detection.

Furthermore, the filtration residue (1) was placed in 600 mL of 60% (v/v) aqueous ethanol and subjected to an ethanol extraction process by leaving the mixture at room temperature for 3 days. It was then subjected to filtration using a filter (pore size: 5 μm), yielding 448.6 g of filtrate (2). The entire amount of filtrate (2) was subjected to vacuum concentration to obtain crude extract (2) as a second extract. The DDK content in crude extract (2) was 150.8 mg, but DK was below the lower limit of detection.

An aqueous solution containing 4.0 g of sodium hydroxide and 1.0 g of glucose was added to extract (1+2), which was the combined total of crude extract (1) and crude extract (2). Water was then added to bring the total volume to 100 mL. The resulting aqueous solution (pH 14) was stirred (150 rpm) at room temperature for 5 hours, then subjected to alkali treatment by leaving it to stand for 19 hours, and then centrifuged (2600 x g, 4,000 rpm, 1 minute). The resulting precipitate was freeze-dried to yield 352.8 mg of powdered shell ginger extract.

The resulting shell ginger extract contained 349.3 mg of DDK (purity 99.0%). Furthermore, based on the amount of DDK contained in the crude extract (1+2), the recovery rate of DDK in the shell ginger extract was 82%.

The shell ginger extract produced by the method of one embodiment of the present invention contains dihydro-5,6-dehydrokawain and 5,6-dehydrokawain in high purity, and can be used in foods and beverages, cosmetics, pharmaceuticals, quasi-drugs, etc., taking advantage of their pharmacological effects. It is particularly useful as an oral agent, topical agent, injection, lotion, etc., or as an ingredient in these products.

Claims (8)

A step of obtaining a crude shell ginger extract by subjecting the dried shell ginger to an extraction treatment using a dehydrokawain-soluble solvent;
A method for producing a shell ginger extract, comprising the steps of subjecting a crude shell ginger extract to a water treatment, an alkali treatment and salting out to obtain a shell ginger extract. The method according to claim 1 , wherein the crude extract of shell ginger is obtained by subjecting the extract obtained by the extraction process to solid-liquid separation and/or concentration. The method according to any one of claims 1 to 2 , wherein the salting out is performed using at least one sugar selected from the group consisting of glucose, sucrose, and maltose. The method according to any one of claims 1 to 3 , wherein the dehydrokawain-soluble solvent is 30% (v/v) to 90% (v/v) aqueous ethanol. The method according to any one of claims 1 to 4 , wherein the alkaline treatment is an alkaline treatment using sodium hydroxide at a final concentration of 0.5% (w/v) to 6% (w/v). The method according to any one of claims 1 to 5 , wherein the shell ginger extract has a total content of dihydro-5,6-dehydrokawain and 5,6-dehydrokawain of 80% (w/w) or more. The method according to any one of claims 1 to 6, wherein the shell ginger extract has a dihydro-5,6-dehydrokawain content of 70% (w/w) or more and/or a 5,6 -dehydrokawain content of 10% (w/w) or more. The method according to any one of claims 1 to 7 , wherein the shell ginger extract is a solid shell ginger extract.