Patent Description:
Roots and stems of Salacia genus plants have been utilized as natural drugs in the traditional medicine Ayurveda of India and Sri Lanka. In Sri Lanka, it has been passed down that the root bark of Salacia reticulata is effective for the treatment of rheumatism, gonorrhea, and skin diseases, and that the above-mentioned root bark is used for the treatment of early stage diabetes mellitus.

In recent year, it has been reported that a Salacia genus plant extract has an effect of inhibiting a rise in the blood glucose level by a sugar absorption suppressing action based on α-glucosidase activity inhibition (for example, Non-Patent Document <NUM>), and a Salacia genus plant extract includes various polyphenols (and mangiferin, which is xanthene glycoside) (for example, Non-Patent Document <NUM>).

These components are perceived as bitter taste, astringent taste, astringency, harsh taste, and odd taste, and there is a risk that these components may give unpleasant feeling to the consumers when ingested as foods.

Meanwhile, examples of a substance containing polyphenols similarly to the Salacia genus plant extract include a tea extract and a Gymnema sylvestre extract.

In Patent Document <NUM>, disclosed is a method for producing a purified green tea extract for the purpose of reducing flavonols without significantly impairing the recovery rate of catechins and thereby providing a purified green tea extract that is useful as a raw material for a catechin-containing beverage having excellent green tea flavor and easy to drink, the method including bringing an organic solvent aqueous solution of a green tea extract into contact with a particular amount of activated carbon for a predetermined time. In Patent Document <NUM>, disclosed is a method for producing a tea extract for the purpose of providing a method for producing a tea extract, by which a deep-bodied tea extract having satisfactory aftertaste and flavor is obtained, the method including an extraction step of extracting tea leaves in the presence of a particular amount of activated carbon. In Patent Document <NUM>, disclosed is a method for purifying a polyphenol-containing composition for the purpose of effectively performing bleaching with excellent safety without impairing the polyphenol content, and also providing a polyphenol-containing composition having unpleasant taste eliminated, with reduced precipitation, and having excellent flavor, the method including bringing a composition containing polyphenols into contact with activated carbon that has been treated at low temperature in advance.

Furthermore, in Patent Document <NUM>, disclosed is a Gymnema sylvestre essence having improved flavor, which is obtained by bringing the leaves of Gymnema sylvestre or an essence obtained by extracting the leaves into contact with activated carbon, and eliminating insoluble materials.

<CIT> describes a salacia extract that is obtained by reducing the polyphenol content in a polyphenol-containing salacia crude extract.

<CIT> describes a compound that is said to have an inhibitory effect against α-glucosidase and to be useful as a medicine for diabetes mellitus. The compound is obtained by extraction-treating the plant Salacia prinoides in the family Celastraceae with hot methanol, phase partitioning the obtained methanol extract with ethyl acetate and water, followed by the fractionation of the obtained aqueous phase by chromatography. The compound can be prepared in crystal, so that it can also be used as a tablet or granule by mixing it with an appropriate vehicle or lactose or starch, as well as an additive to chewing gum, chocolate, bread, noodle, candy, and so on. The compound is administered for an adult at a rate of <NUM>-<NUM> per dose <NUM>-<NUM> before meal or added to foods in an amount of <NUM>-<NUM> wt.

<NPL>, describes the isolation of mangiferin, three catechins, and two catechin dimers from the roots of Salaciareticulata (SRE), and the examination of their inhibitory activities against several carbohydrate metabolize enzymes (sucrase, maltase, isomaltase, α-amylase, and aldose reductase).

<CIT> describes a melanin-formation inhibitor that comprises at least one plant extract selected from among Salacia reticulata, Salacia chinensis and Salacia oblonga.

<CIT> describes a method for producing a beverage containing an extract of a plant of genus Salacia, characterized by thermal sterilization of the extract in a manner to keep α-glucosidase inhibiting activity even in an aqueous solution of pH <NUM>-<NUM> or thereabout. The method includes a thermal sterilization of an aqueous solution containing <NUM>-<NUM> wt. % of an extract of a plant of the genus Salacia at ≥<NUM> and ≤<NUM> while setting an F value to ≤<NUM> and pH of the aqueous solution to ≥<NUM> and ≤<NUM>.

<CIT> describes a method to obtain Gymnema sylverstre extract wherein, to <NUM> parts by weight of the dried leaves of Gymnema Sylvestre, <NUM>-<NUM> parts by weight of activated carbon is added, and simultaneously with the addition of the activated carbon or after such addition, water or warm water is added, followed by agitation and extracting operation to obtain the objective Gymnema Sylvestre extract.

<CIT> describes an essence of Gymnema Sylvestre R. that is produced by extraction-treating a leaf of the Gymnema Sylvestre R. with water or a hydrophilic organic solvent or a mixed solvent thereof, more preferably ethanol with <NUM>-<NUM> wt. % water content in the presence of an active carbon prewetted with water, more preferably the active carbon having <NUM>,<NUM>-<NUM>,<NUM><NUM>/g specific surface area, pH <NUM>-<NUM> and <NUM>-<NUM> wt. % water content, removing insoluble materials and further suitably concentrating, drying and powdering the resultant extract.

<CIT> describes a guava leaf extract that is obtained by carrying out the extraction of a guava leaf in the presence of an activated carbon, more preferably the one having <NUM>,<NUM>-<NUM>,<NUM><NUM>/g specific surface area, pH <NUM>-<NUM> and <NUM>-<NUM> wt. % water content, previously wetted by water, with the water, a hydrophobic organic solvent or a mixture thereof, more preferably ethanol having <NUM>-<NUM> wt. % water content, removing an insoluble matter from the obtained extract, and optionally condensing, drying and powdering the resultant extract.

<CIT> describes a method for producing a purified tea extract characterized in that a tea extract, which contains an aqueous solution of an organic solvent, is brought into contact with an anion exchange resin.

However, it was found that in order to obtain a Salacia genus plant extract that does not require processing into a pharmaceutical preparation, a food product, or the like and is appropriate for the use for oral intake, in a case in which a Salacia genus plant extract is purified by the treatments described in Patent Documents <NUM> to <NUM> for the purpose of improving the flavor, the recovery rate of the Salacia genus plant extract and the α-glucosidase activity inhibitory action are decreased, and reduction of the flavor, particularly the odor and bitter taste characteristic of Salacia genus plants is insufficient.

A decrease in the recovery rate of a Salacia genus plant extract by purification is not preferable from the viewpoint of the production cost. Since a decrease in the α-glucosidase activity inhibitory action leads to a reduction in the activity of the Salacia genus plant extract, the one-time amount of intake should be increased, and therefore, there is a risk that the burden on the intaker may increase. Furthermore, in order to obtain an extract that can be directly taken in orally without being subjected to processing into a pharmaceutical preparation, a food product, or the like, it is important to produce an extract that has improved flavor and can be easily taken in.

According to an embodiment of the present invention, in view of the problems as described above, it is an object of the invention to provide a method for producing a purified Salacia genus plant extract having improved flavor while maintaining the α-glucosidase inhibitory activity of the extract, without significantly reducing the recovery rate of the extract concomitantly with purification.

Generally, since the raw material for obtaining a purified Salacia genus plant extract is at a high concentration compared to a tea extract or the like, the recovery rate can be easily decreased by purification, and therefore, purification treatment is not carried out.

However, the inventors of the present invention conducted a thorough investigation, and thereby the inventors clarified that a step of bringing a Salacia genus plant-containing raw material extract comprising at least one of a Salacia genus plant, a Salacia genus plant extract, and a Salacia genus plant ground product, into contact with <NUM> to <NUM> mass% of activated carbon, with respect to the Salacia genus plant-containing raw material extract, in the presence of an extraction solvent, is effective in solving the problems described above. Furthermore, surprisingly, it was found that according to the production method of the present disclosure, the α-glucosidase inhibitory activity can be enhanced.

In this regard, the present inventors speculate as follows.

It is speculated that the flavor (odor and bitter taste) characteristic of Salacia genus plants is caused by the components (hereinafter, also referred to as "particular components") such as polyphenols and lipids contained in the Salacia genus plants. Since activated carbon has low affinity with active ingredients such as salacinol but has high affinity with these particular components, it is speculated that by performing a treatment with activated carbon that is brought into contact in a particular amount, the above-mentioned particular components are selectively removed, thus the content of the particular components included in the resulting purified Salacia genus plant extract is relatively reduced, and as a result, the flavor of the Salacia genus plant extract is improved.

It is considered that the α-glucosidase inhibitory activity effect, which has been slightly reduced as the particular components exert a certain action on the active ingredients such as salacinol, is increased by selective removal of the particular components, and as a result, the α-glucosidase inhibitory activity of the purified Salacia genus plant extract can be increased.

The speculation described above is not intended to limitedly analyze the effects of an embodiment of the invention but is intended to describe the embodiment as an example.

Specific means for solving the problems described above include the following embodiments.

According to an embodiment of the present invention, a method for producing a purified Salacia genus plant extract, by which an odor characteristic of Salacia genus plants is improved while the α-glucosidase inhibitory activity of the extract is maintained, without significantly reducing the recovery rate of the extract concomitantly with purification; and a purified Salacia genus plant extract can be provided.

Hereinafter, an example of the embodiments of the invention will be explained.

The numerical value range expressed using the symbol "~" according to the present specification means a range including the numerical values described before and after the symbol "~" as the minimum value and the maximum value, respectively.

With regard to a numerical value range described stepwise in the present specification, the upper limit or lower limit described in one numerical value range may be substituted for the upper limit or the lower limit of another numerical value range described stepwise. Furthermore, with regard to the numerical value ranges described in the present specification, the upper limit or the lower limit of the numerical value range may be substituted for the values disclosed in Examples.

According to the present specification, the term "step" means not only an independent step; however, in a case in which a step cannot be clearly distinguished from other steps, as long as the predetermined purpose of the step is achieved, the step is included in the present term.

Salacia genus plants are plants of the family Hippocrateaceae growing naturally mainly in Sri Lanka, India, and the South-East Asia region. Specific examples of a Salacia genus plant include one or more plants selected from Salacia reticulata, Salacia oblonga, Salacia prinoides, Salacia chinensis, Salacia latifolia, Salacia burunoniana, Salacia grandiflora, or Salacia macrosperma. The Salacia genus plant is preferably at least one plant selected from Salacia reticulata, Salacia oblonga, or Salacia chinensis.

According to the present disclosure, the term "Salacia genus plant-containing raw material extract" means components derived from a Salacia genus plant among the raw material for obtaining a purified Salacia genus plant extract in the extraction step, and other components included in the extract (for example, an extraction solvent used for preparing the raw material) are excluded.

According to the present disclosure, at least one of a Salacia genus plant, a Salacia genus plant extract, and a Salacia genus plant ground product may be used as the Salacia genus plant to be used for the Salacia genus plant-containing raw material extract. As the Salacia genus plant, edible parts such as roots, stems, leaves, flowers, and fruits of Salacia genus plants can be directly used.

According to the present specification, an extract of a Salacia genus plant and a ground product of a Salacia genus plant are used to mean to include an extract and/or ground product of edible parts such as roots, stems, leaves, flowers, and fruits of Salacia genus plants, and dried products of the extract and/or ground product. According to the present specification, a dried product may be a dried powder (essence powder). At the time of preparing the above-described extract and/or ground product of a Salacia genus plant, one or more kinds of sites of the Salacia genus plant may be used as a mixture. From the viewpoint of producing a purified Salacia genus plant extract efficiently, as the Salacia genus plant-containing raw material extract, preferably, an extract powder obtainable by drying a Salacia genus plant extract (essence) extracted from a site selected from roots and stems, or an essence powder obtainable by drying an essence is used.

A dried powder (essence powder) can be preferably obtained by extracting edible parts and the like of a Salacia genus plant by means of a solvent and drying an extract obtained as described above.

Examples of the solvent that is used for extraction include water, an alcohol, and a ketone, and a mixed solvent obtained by mixing two or more kinds of these may also be used.

Examples of the alcohol include methanol and ethanol, and ethanol is preferred.

Regarding the ketone, acetone, methyl ethyl ketone, cyclohexane, and the like are preferred.

Among those described above, water, an alcohol, a mixed solvent of water and an alcohol, or a mixed solvent of water and a ketone is preferred; water, an alcohol, or a mixed solvent of water and an alcohol is more preferred; and hot water at <NUM> to <NUM>, ethanol, or a mixed solvent of water and ethanol is even more preferred.

The alcohol content in the mixed solvent of water and an alcohol is preferably <NUM> mass% to <NUM> mass%, and more preferably <NUM> mass% to <NUM> mass%.

The drying method used at the time of drying an extract and thereby obtaining a dried powder (essence powder) is not particularly limited, and known drying methods, for example, methods such as spraying drying and freeze-drying may be mentioned.

The method for producing a purified Salacia genus plant extract of the present disclosure includes an extraction step of bringing a Salacia genus plant-containing raw material extract comprising at least one of a Salacia genus plant, a Salacia genus plant extract, and a Salacia genus plant ground product, into contact with <NUM> to <NUM> mass% of activated carbon, with respect to the Salacia genus plant-containing raw material extract, in the presence of an extraction solvent.

The activated carbon to be used for the present disclosure can be used without any particular limitations on the type, characteristics, and the like of the activated carbon. Examples of the carbonaceous material of activated carbon include plant-based cokes of coconut shell, palm, fruit seeds, sawdust, Eucalyptus, pine, and the like; coal-based and petroleum-based cokes; carbides of pitches obtained by using those as raw materials; a phenolic resin, a vinyl chloride resin, and a vinylidene chloride resin; however, carbonaceous materials derived from plant-based materials such as coconut shell, palm, fruit seeds, sawdust, Eucalyptus, and pine are preferred.

Regarding the activated carbon, commercially available products can be used, and examples include SHIRASAGI (registered trademark) C, SHIRASAGI WH2c, SHIRASAGI W2c, SHIRASAGI WH2x, SHIRASAGI X7000H, SHIRASAGI X7100H, SHIRASAGI LGK-<NUM>, SHIRASAGI WHA, SHIRASAGI M, SHIRASAGI A, SHIRASAGI P, CARBORAFFIN, KYOURYOKU SHIRASAGI, SEISEI SHIRASAGI, TOKUSEI SHIRASAGI, granular SHIRASAGI LH2c, granular SHIRASAGI KL, granular SHIRASAGI MAC-W (all trade names, manufactured by Osaka Gas Chemicals Co. ); TAIKO S type (TAIKO S, TAIKO DP, TAIKO SA1000); and TAIKO K type (TAIKO K, TAIKO A, TAIKO KA, TAIKO M) (all trade names, manufactured by Futamura Chemical Co. Products obtained by subjecting these activated carbons to further purification treatment may also be used.

The average pore diameter of the activated carbon is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, even more preferably <NUM> to <NUM>, and still more preferably <NUM> to <NUM>, from the viewpoint of obtaining a purified Salacia genus plant extract having further enhanced α-glucosidase activity inhibition.

The specific surface area of the activated carbon is preferably <NUM> to <NUM>,<NUM><NUM>/g, more preferably <NUM>,<NUM> to <NUM>,<NUM><NUM>/g, and even more preferably <NUM>,<NUM> to <NUM>,<NUM><NUM>/g, from the viewpoint of increasing the recovery rate.

The detailed mechanism is not certainly understood; however, it is speculated that it is because the activity of a compound exhibiting α-glucosidase activity inhibition can be further increased as the activated carbon selectively removes particular components included in the Salacia genus plant extract.

Regarding the average pore diameter and specific surface area of the activated carbon, in a case in which the activated carbon is a commercially available product, the values described in catalogues can be employed. Furthermore, regardless of being a commercially available product or not, in a case in which these values are not clearly known, the values can be measured by the methods for measuring a specific surface area based on gas adsorption according to JIS Z <NUM> (<NUM>) and ISO <NUM> (<NUM>).

From the viewpoint of reducing bitter taste, the amount of the activated carbon to be contacted is <NUM> mass% or more, and preferably <NUM> mass% or more, with respect to the Salacia genus plant-containing raw material extract. Furthermore, from the viewpoint of increasing the recovery rate, the amount is <NUM> mass% or less, with respect to the Salacia genus plant-containing raw material extract.

The time for contacting with activated carbon is preferably <NUM> minutes or longer, and more preferably <NUM> minutes or longer, from the viewpoint of efficiently obtaining a purified Salacia genus plant extract. From the viewpoint of obtaining a purified Salacia genus plant extract having further enhanced α-glucosidase activity inhibition, the time is preferably <NUM> hours or shorter, and more preferably <NUM> hours or shorter.

Regarding the extraction solvent, any solvent can be used without any particular limitations on the type, characteristics, and the like thereof, and water and/or an organic solvent can be used; however, from the viewpoint of the production cost, the extraction solvent is preferably water. The type of water is not particularly limited, and water can be appropriately selected from tap water, distilled water, ion-exchanged water, natural water, and the like, and used.

Furthermore, in the case of using an organic solvent, for example, examples include alcohols such as ethanol and methanol; ketones such as acetone; and esters such as ethyl acetate. A hydrophilic organic solvent such as an alcohol or a ketone is preferred, and in consideration of the use in pharmaceutical preparations or food products, an alcohol is more preferred, while ethanol is even more preferred.

The extraction solvent may be the extraction solvent include in the Salacia genus plant-containing raw material extract described above. That is, the solvent used to prepare a Salacia genus plant extract (essence) that serves as a raw material may be used directly as the extraction solvent.

The temperature at the time of contacting with activated carbon is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, even more preferably <NUM> to <NUM>, and still more preferably <NUM> to <NUM>, from the viewpoint of increasing the α-glucosidase activity inhibition ability of the purified Salacia genus plant extract thus obtained.

Regarding the means for contacting with activated carbon, any known method can be employed without any particular limitations. For example, a batch method of adding an extraction solvent and activated carbon to an extract of a Salacia genus plant or a ground product of a Salacia genus plant, stirring the mixture to adsorb, and then collecting the activated carbon by a filtration operation; or a column method of using a column packed with activated carbon and bringing the mixture into contact by a continuous treatment, may be mentioned.

Since a batch system can easily realize contacting for a long time, the batch system can be preferably used from the viewpoint of productivity.

A method of adding an extraction solvent to a Salacia genus plant-containing raw material extract, subsequently gradually heating the extraction solvent, and then adding activated carbon is preferred from the viewpoint of productivity.

An extract obtained by performing the extraction step is subjected to one kind or a combination of two or more kinds of solid-liquid separation treatments selected from filtration, centrifugation, a precipitation treatment, a membrane treatment, or the like, thereby solid components of the Salacia genus plant and activated carbon are removed, and a purified Salacia genus plant extract can be obtained.

The method for filtration is not particularly limited, and for example, filtering separation by means of a filter paper, a metal filter, or a gas filter can be employed. The mesh size of the filter is not particularly limited as long as the solid components of the Salacia genus plant and the activated carbon can be reliably removed.

Centrifugation can be carried out using, for example, a known device such as a separation plate type, a cylindrical type, or a decanter type device, without any particular limitations. The use conditions (rotation speed and time) of centrifugation are not particularly limited as long as the solid components of the Salacia genus plant and the activated carbon can be reliably removed.

A membrane treatment is a treatment of passing through, for example, a membrane formed from a polymer material having a pore diameter of <NUM> or less, and examples of the form of the membrane include a flat membrane and a hollow fiber membrane.

In the separation step, from the viewpoint of increasing the purification efficiency, a concentration step of increasing the concentration of the extract obtained in the extraction step through concentrating or drying may be added, or a concentration step may be utilized in the middle of the separation step.

Through the production method of the present disclosure as described above, an odor and bitter taste characteristic of Salacia genus plants are reduced while the recovery rate and the α-glucosidase activity inhibition are maintained, and thus the content of the Salacia genus plant in the extract can be increased. As a result, a purified Salacia genus plant extract that can be orally taken in without being subjected to processing into a pharmaceutical preparation, a food product, or the like, can be obtained.

After the purified Salacia genus plant extract (purified essence) is obtained through the above-described extraction step, the essence may be concentrated (concentrated purified essence) or dried (purified essence powder). The concentration or drying method is not particularly limited, and known methods may be used.

Meanwhile, according to the present specification, the "recovery rate of the Salacia genus plant extract" or the "recovery rate" means the solid content, as expressed in percentage, of the purified Salacia genus plant extract with respect to the solid content of a Salacia genus plant extract obtainable without performing the extraction treatment described above. Meanwhile, the upper limit of the recovery rate is not particularly limited and may be <NUM> mass%.

The purified Salacia genus plant extract obtained by the production method of the present disclosure has excellent storage stability over time. Specifically, coloration and odor generation caused by storage at room temperature can be reduced. The detailed mechanism in this regard is not clearly understood; however, it is speculated that as the above-mentioned particular components are selectively removed, denaturation of the particular components caused by the influence of moisture in air concomitant with time lapse, or a reaction between the particular components and the active ingredients in the Salacia genus plant extract can be suppressed, the storage stability of the purified Salacia genus plant extract is improved.

Since the purified Salacia genus plant extract of the present disclosure has improved flavor, the extract is an extract that can be orally taken in without being subjected to processing into a pharmaceutical preparation, a food product, or the like. Specifically, the odor and bitter taste characteristic of Salacia genus plants have been reduced, and the purified Salacia genus plant extract has characteristics as described below.

In the purified Salacia genus plant extract, the contents of the sum of polyphenols and lipids are <NUM> mass% or more and less than <NUM> mass% in total with respect to the total amount of the purified Salacia genus extract.

According to the present specification, the polyphenols mean compounds that can be measured by the FOLIN-CIOCALTEU method according to ISO <NUM>-<NUM> (<NUM>), and examples include catechins. Furthermore, the lipids mean compounds that can be measured by an acid decomposition method, which is used for the analysis of lipids in a food product, and examples include cholesterol and glycerin.

Since the purified Salacia genus plant extract of the present disclosure has the polyphenols and lipids reduced as described above, the odor and bitter taste characteristic of Salacia genus plants are reduced, and the coloration and odor generation concomitant with storage over time can be reduced.

The purified Salacia genus plant extract may be dried (purified essence powder), may be produced into a powder with added excipients and the like, or may be subjected to a granulation treatment and produced into a granulation product having a large particle size. Regarding the excipients, the types, characteristics, and the like can be used without particular limitations.

The bitter taste of the purified Salacia genus plant extract can be judged by using the content of epicatechin among the polyphenols as an index. From the viewpoint of further reducing bitter taste, the content of epicatechin with respect to the total amount of the purified Salacia genus extract is preferably less than <NUM> mass%, and more preferably less than <NUM> mass%. Regarding the lower limit, for example, the content of epicatechin with respect to the total amount of the purified Salacia genus extract is <NUM> mass% or more.

The purified Salacia genus plant extract of the present disclosure has an α-glucosidase activity inhibition ability.

The sucrase <NUM>% inhibition concentration (IC<NUM> value) as an index of the α-glucosidase inhibitory activity can be measured by the following method.

<Experiment method <NUM>> Preparation of sample solution for measuring sucrase IC<NUM> value: <NUM> of a sample is measured into a tube, <NUM> of water is added thereto to suspend the sample, and thus a sample solution having a concentration of <NUM>/mL is created. This is diluted with water so as to obtain concentrations of <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>µg/mL, respectively.

Preparation of substrate solution: Sucrose is dissolved in a <NUM> mol/L maleic acid buffer (pH <NUM>) so as to obtain a sucrose concentration of <NUM> mmol/L, and this is used as a substrate solution.

Preparation of crude enzyme solution: <NUM> of intestinal acetone powder rat (manufactured by SIGMA Corporation) is suspended in <NUM> of physiological saline, and the suspension is centrifuged (<NUM>,<NUM> rpm, <NUM>, <NUM> minutes). A supernatant thus obtained is separated and used as a crude enzyme solution.

<NUM>µL of the substrate solution was added to <NUM>µL of each of the sample solutions of various concentrations described above, and the mixture was preliminarily heated in a water bath at <NUM> for <NUM> minutes. To each of these, <NUM>µL of the crude enzyme solution was added, and the mixtures were reacted for <NUM> minutes at <NUM>. After completion of the reaction, the enzyme was deactivated by heating at <NUM> for <NUM> minutes, and thus the reaction was terminated. The glucose concentration thus produced is quantitatively analyzed using a commercially available Kit-Mutarotase Glucose Oxidase Method (GLUCOSE CII TEST WAKO, manufactured by Wako Pure Chemical Industries, Ltd.

Preparation of blank: To <NUM>µL of each of the sample solutions of various concentrations described above, <NUM>µL of the substrate solution and <NUM>µL of the crude enzyme solution are added, and the mixture is immediately heated at <NUM> for <NUM> minutes to thermally deactivate the enzyme, and this is used as the blank data.

A calibration curve is produced from the values thus obtained, and the concentration at which <NUM>% of the enzyme activity is inhibited (IC<NUM> value) is determined.

The content of salacinol in the composition can be checked by detecting by high performance liquid chromatography under the following conditions.

The flavor of the purified Salacia genus plant extract of the present disclosure can be evaluated using a taste sensor.

The taste sensor according to the present disclosure is made to imitate a human taste detection system, and performs evaluation by measuring the responsiveness to a taste substance toward a sensor using an artificial lipid membrane.

In the artificial lipid membrane used in the sensor of a taste sensor, since the responding taste substance varies depending on the type of lipid, the mixing ratio of a plasticizer, and the like, different responsiveness to the basic five tastes such as sour taste, salty taste, sweet taste, bitter taste, and umami taste is exhibited by changing the type of the artificial lipid membrane. By utilizing this property, taste detection corresponding to each taste can be performed, and furthermore, in order to distinguish the foretaste and the aftertaste, the taste sensor can digitize and express taste through a plurality of items.

The artificial lipid membrane is stuck to the taste sensor surface, and as this membrane is immersed in a sample solution, there occurs a change in the membrane potential of the lipid membrane. As such, the amount of change in the membrane potential occurring in a case in which the taste substance included in a sample solution adsorbs to the sensor surface is treated as the sensor output value, and thereby the taste of the measurement sample can be judged comprehensively.

Regarding the measurement, first, a taste sensor is immersed into a solution that serves as a reference (hereinafter, also referred to as "reference solution"), and the membrane potential Vr is obtained. Next, as the taste sensor is immersed in a sample solution, the membrane potential Vs, which has changed as a result of an interaction with a taste substance, is obtained. From this difference (Vs - Vr), a relative value of the sensor output is calculated, and this is a value corresponding to the foretaste.

Regarding the aftertaste, after the foretaste is measured by the method described above, the taste sensor is simply prewashed with the reference solution and is immersed again in the reference solution, and the membrane potential Vr' is obtained. Thereby, from this membrane potential change (Vr' - Vr), the aftertaste can be determined as a CPA (Change of membrane Potential by Adsorption) value. The results obtained at the time of using a <NUM> mmol/L tartaric acid solution containing <NUM> mmol/L potassium chloride as a reference solution are used as the measured values.

There are no particular limitations on the environmental temperature at the time of measurement; however, it is preferable that the measurement is carried out at room temperature (<NUM> to <NUM>), normal temperature (<NUM> to <NUM>), standard temperature (<NUM>), or the like as defined in the Japanese Pharmacopeia.

According to the present disclosure, the foretaste is the taste felt immediately after a food is taken into the mouth, and in a case in which the foretaste is evaluated as a taste item by the above-described measurement, the foretaste is expressed as "sour taste", "bitter taste and odd taste", "astringent taste and stimulation", "umami taste", and "salty taste". On the other hand, the aftertaste is the taste remaining in the tongue even after the food is swallowed, and in a case in which the aftertaste is evaluated as a taste item by the above-described measurement, the aftertaste is expressed as "bitter taste", "astringent taste", or "umami taste and richness".

The taste sensor that can be used for the present disclosure is not particularly limited; however, it is preferable to use a taste sensor having high responsiveness to the above-mentioned five basic tastes, and above all, it is more preferable to use a taste sensor having high responsiveness to sour taste, salty taste, bitter taste, umami taste, and astringent taste, from the viewpoint of analyzing the causes of the odor and bitter taste characteristic of Salacia genus plants, which significantly affect the flavor. Furthermore, the taste items obtained as the foretaste and/or aftertaste described above can also be used for the evaluation.

Regarding a commercially available measuring apparatus, for example, a taste perception apparatus, TS-5000Z (Intelligent Sensor Technology, Inc. ), may be mentioned.

From the viewpoint of reducing the causes of the odor and bitter taste characteristic of Salacia genus plants, which significantly affect the flavor, the purified Salacia genus plant extract of the present disclosure is preferably such that the bitter taste and odd taste in the foretaste is <NUM> or less, the astringent taste and stimulation in the foretaste is <NUM> or less, the bitter taste in the aftertaste is <NUM> or less, and the astringent taste in the aftertaste is <NUM> or less. As these values are smaller, a purified Salacia genus plant extract giving a reduced level of taste that gives unpleasant feeling to the consumers is obtained, and therefore, there are no particular limitations on the lower limits.

The use of the purified Salacia genus plant extract of the present disclosure is not particularly limited, and examples include food products (including beverages and supplements), food materials, quasi-drugs, pharmaceutical products, pharmaceutical materials, and quasi-drug materials. Specifically, the description of paragraphs <NUM> to <NUM> of <CIT> may be mentioned. In a case in which he purified Salacia genus plant extract of the present disclosure is applied to a food product, a food material, a quasi-drug for oral intake, a pharmaceutical product, a pharmaceutical material, and a quasi-drug material, the effects of the present disclosure act more effectively.

Hereinafter, the present invention will be described more specifically by way of Examples.

The root parts of Salacia reticulata were ground and then extracted with hot water at <NUM>, a solution thus obtained was concentrated, and a Salacia genus plant-containing raw material extract (solid content concentration <NUM> to <NUM> mass%) was obtained.

Examples <NUM> to <NUM> and Comparative Examples <NUM> and <NUM> were produced in the same manner as in Example <NUM>, except that the type and concentration of the activated carbon, the treatment temperature, and the treatment time were changed as described in the following tables.

Comparative Example <NUM> was produced in the same manner as in Example <NUM>, except that the extraction step described in II. <NUM>) was not carried out.

For the purified Salacia genus plant extracts of Examples and Comparative Examples, the following various evaluations were carried out. The results are presented in the following tables.

While the recovery rate of Comparative Example <NUM> was taken as <NUM> mass%, the recovery rates of Examples <NUM> to <NUM> and Comparative Examples <NUM> and <NUM> were calculated.

The salacinol concentrations of Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM> were measured by the Experiment method <NUM> described above. Subsequently, while the salacinol concentration of Comparative Example <NUM> was taken as <NUM> mass%, the salacinol concentrations of Examples and Comparative Examples were calculated.

The salacinol recovery rates of Examples and Comparative Examples were calculated on the basis of the following formula.

The sucrase IC<NUM> values of Examples and Comparative Examples were measured by the Experiment method <NUM> described above. Subsequently, the α-glucosidase inhibitory activity of Examples and Comparative Examples was calculated on the basis of the following formula.

An evaluation was carried out by five test subjects by the following procedure.

Meanwhile, A, B, or C is in the range of being acceptable as a manufactured product.

A sample was dissolved in pure water to a concentration of <NUM>%, and the absorbance at a wavelength of <NUM> was measured by ultraviolet-visible spectroscopy using a cell having an optical path length of <NUM>.

An ultraviolet-visible spectrophotometer (model name: U-<NUM>, Hitachi, Ltd. ) was used as the measuring apparatus, and pure water was used for a blank test.

The content of epicatechin in each of Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM> was measured by a HPLC-mass analysis method. While Comparative Example <NUM> was taken as <NUM>, the content ratios of epicatechin of Examples <NUM> to <NUM>, Comparative Example <NUM>, and Comparative Example <NUM> were calculated.

The content of polyphenol (epicatechin) in a composition was quantitatively determined by detecting by high-performance liquid chromatography under the following conditions.

A sample was encapsulated in a sample bottle and stored for one month in an atmosphere of <NUM>, and then the generation of coloration and an odor after a lapse of time were evaluated by the following procedure.

The coloration of the sample after storage was evaluated by a procedure similar to "<NUM>. Evaluation of coloration" as described above.

The odor of the sample after storage was evaluated by a procedure similar to "<NUM>. Evaluation of odor" as described above.

From the above results, Examples <NUM> to <NUM> all exhibited high recovery rates while having satisfactory effects of reducing the odor and bitter taste characteristic of Salacia genus plants. Furthermore, surprisingly, Examples <NUM> to <NUM>, <NUM>, and <NUM> exhibited satisfactory α-glucosidase inhibitory activity compared to Comparative Example <NUM> (sample that was not subjected to the extraction step using activated carbon of the present disclosure).

Example <NUM> and Examples <NUM> to <NUM> had very low content ratios of epicatechin among polyphenols, compared to Comparative Example <NUM>. Therefore, it is considered that Examples <NUM> to <NUM> have satisfactory effects of ameliorating bitter taste as described in the tables. Furthermore, Examples <NUM> to <NUM> had the generation of coloration and odor suppressed even after a lapse of time and had satisfactory storage stability.

For Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM>, an evaluation of flavor was carried out using taste sensors.

<NUM> of water was added to <NUM> of a sample, and the mixture was stirred. This was used as a test solution for each case.

As a reference solution, a <NUM> mmol/L tartaric acid solution containing <NUM> mmol/L potassium chloride was prepared.

An analysis of the taste of the test solution was carried out using a taste perception apparatus according to the measurement conditions described below. That is, five items of the foretaste (sour taste, bitter taste and odd taste, astringent taste and stimulation, umami taste, and salty taste) and three items of the aftertaste (bitter taste, astringent taste, and umami taste and richness) were measured using five kinds of taste sensors. Specifically, the measurement potential in the reference solution of each of the five kinds of taste sensors was designated as zero, and the difference with the measurement potential in the test solution was designated as the foretaste. Subsequently, the respective taste sensors were washed with the reference solution, and the difference in the potential at the time of measuring the reference solution again was designated as the aftertaste.

For the analysis of the measurement results thus obtained, an analysis application affiliated to the apparatus was used.

Taste sensors of CA0, C00, AE1, AAE, and CT0 were used, and the taste sensors were allowed to judge the taste. The content of determination was converted to the various taste items as described below and then was outputted.

As an index of the odor and bitter taste characteristic of Salacia genus plants, which significantly affect the flavor, measurement results on four types of taste items (bitter taste and odd taste in the foretaste, astringent taste and stimulation in the foretaste, bitter taste in the aftertaste, and astringent taste in the aftertaste) were evaluated.

From the above results, the evaluation results for the flavor provided by taste sensors (four types of taste items) and the results of performing an evaluation in <NUM>. Evaluation of odor and <NUM>. Evaluation of bitter taste were found to be correlated. Specifically, the purified Salacia genus plant extracts of Examples <NUM> to <NUM>, in which the bitter taste and odd taste in the foretaste was <NUM> or less, the astringent taste and stimulation in the foretaste was <NUM> or less, the bitter taste in the aftertaste was <NUM> or less, and the astringent taste in the aftertaste was <NUM> or less, exhibited satisfactory results also in the evaluation results for odor or bitter taste provided by human beings.

Claim 1:
A method for producing a purified Salacia genus plant extract, the method comprising an extraction step of bringing a Salacia genus plant-containing raw material extract comprising at least one of a Salacia genus plant, a Salacia genus plant extract, or a Salacia genus plant ground product, into contact with <NUM> to <NUM> mass% of activated carbon, with respect to the Salacia genus plant-containing raw material extract, in the presence of an extraction solvent.