Method for manufacturing composition containing nobiletin and tangeretin derived from citrus fruits, and composition containing nobiletin and tangeretin obtained thereby

Abstract

The object is to provide a method of manufacturing a fraction containing nobiletin and tangeretin at high concentrations, which is excellent in terms of safety, economic efficiency, and the potential for industrialization. The method includes (1-1) a step of treating citrus fruit with hot water to obtain a hot water-treated product; (1-2) a step of drying the hot water-treated product to obtain a dried product; (1-3) a step of treating the dried product with a solvent capable of dissolving nobiletin and tangeretin to obtain a nobiletin and tangeretin solution; (3) a step of concentrating and/or drying the nobiletin and tangeretin solution to obtain a nobiletin and tangeretin concentrate; and (4) a step of treating the nobiletin and tangeretin concentrate with a dilute alkali to obtain a composition containing nobiletin and tangeretin as an insoluble component, and by a composition containing nobiletin and tangeretin at high concentrations manufactured by the method.

Claims

1. A method of manufacturing a composition containing nobiletin and tangeretin, comprising the following Steps (2), (3) and (4): (2) a step of treating fruit, fruit peel, or pomace of citrus fruit with 20 to 70% (v/v) ethanol that is maintained at a temperature of 50 C. to 70 C. to obtain a nobiletin and tangeretin solution, wherein the nobiletin and tangeretin solution is obtained as a liquid component by filtration with a filter having a retention particle size of 3 m to 10 m; (3) a step of concentrating and/or drying the nobiletin and tangeretin solution to obtain a nobiletin and tangeretin concentrate; and (4) a step of treating the nobiletin and tangeretin concentrate with a 0.1% to 20% (w/v) aqueous alkaline solution to obtain a composition containing nobiletin and tangeretin as an insoluble component.

2. The method according to claim 1, wherein the Step (2) is a step of treating citrus fruit for 1 to 8 hours.

3. The method according to claim 1, wherein the solvent is 20 to 50% (v/v) ethanol.

4. The method according to claim 1, wherein the Step (4) is a step of treating the nobiletin and tangeretin concentrate with a 1 to 3% (w/v) aqueous alkaline solution at room temperature to obtain a composition containing nobiletin and tangeretin as an insoluble component.

5. The method according to claim 1, wherein the citrus fruit is at least one plant selected from the group consisting of Citrus depressa, C. unshiu, C. tachibana, C. leiocarpa, C. tardiva, C. succosa, C. kinokuni, C. erythrosa, C. sunki, C. deliciosa, C. nobilis, C. retuculata, C. tangerina, C. hanayu, C. reticulata, C. sunki, C. nippokoreana, shiranuhi, and kiyomi.

6. The method according to claim 1, wherein the step (4) is a step of treating the nobiletin and tangeretin concentrate with a 0.1% to 20% (w/v) aqueous alkaline solution at a temperature of 6 C. to room temperature to obtain a composition containing nobiletin and tangeretin as an insoluble component.

7. The method according to claim 1, wherein the steps (3) and (4) are continuously executed.

Description

EXAMPLES

(1) The contents (mg) of nobiletin and tangeretin were measured by a calibration curve method using a Develosil ODS-HG-5 column as a column and MeOH:H.sub.2O=70:30 as a mobile phase under the conditions set at a flow rate of 1 ml/min and a measurement wavelength of 215.0 nm, by defining the compounds as peaks having retention times of about 8 to 9 minutes and about 11 to 12 minutes, respectively.

(2) The content (mg) of synephrine was measured by a calibration curve method using a Develosil ODS-HG-5 column as a column and CH.sub.3CN:H.sub.2O=2:98 (containing 0.1% TFA) as a mobile phase under the conditions set at a flow rate of 1 ml/min and a measurement wavelength of 223.0 nm, by defining the compound as a peak having a retention time of about 8 to 9 minutes, respectively.

Example 1

(3) 500 g of a pomace of Taiwan tangerine produced from Higashimura in Okinawa Prefecture was thoroughly washed, 1800 mL of distilled water at about 70 C. was added thereto, and the mixture was heat treated by placing the mixture in a water bath at about 70 C. for 3 hours. The heat treated product thus obtained was subjected to suction filtration using a Buchner funnel with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and thus a residue was obtained. The residue was subjected to a squeezing machine and was juiced.

(4) 300 g (wet weight) of the juice waste obtained after juicing was weighed, and the juice waste was dried for 30 minutes at about 60 C. using a dryer (manufactured by Panasonic Corp., product No. EH5101P TurboDry). Thus, 150 g of dried fruit peel was obtained. 30% (v/v) Ethanol in an amount of 2 times the weight of the juice waste was added thereto, and ethanol extraction was carried out for 3 days at room temperature. The extract was subjected to suction filtration using a Buchner funnel provided with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and thus 3200 mg of a filtrate was obtained (After ethanol extraction (1) in Table 1). The filtrate thus obtained was concentrated in a rotary evaporator, and thus a concentrate was obtained.

(5) A 10-fold amount of a 1% (w/v) aqueous solution of sodium hydroxide was added to the concentrate, and the mixture was stirred for 1 day at room temperature using a stirrer. An insoluble component thus obtained was washed with a double amount of water. The residual insoluble component was eluted with a 5- to 10-fold amount of 100% (v/v) ethanol. Subsequently, the ethanol-eluted component was treated to separate a precipitate by filtration using a Buchner funnel. The contents of nobiletin and tangeretin in 66.3 mg of a solid-dried concentrate of the filtrate thus obtained were measured by HPLC, and as indicated in Table 1, the contents were 34.0 mg and 16.8 mg, respectively, while the percentage content was about 77% by weight. Meanwhile, the recovery ratio (%) was determined by assuming the contents of nobiletin and tangeretin included in 500 g of the pomace of Taiwan tangerine as 500 mg.

(6) TABLE-US-00001 TABLE 1 Component Nobiletin Tangeretin Percentage Percentage Recovery Content content Content content ratio Step (mg) (wt %) (mg) (wt %) (%) After ethanol 70.4 2.2 32.0 1.0 20.4 extraction (1) After ethanol 34.0 51.3 16.8 25.4 10.1 elution after alkali treatment (2)

Example 2

(7) 500 g of a pomace of Taiwan tangerine produced from Higashimura in Okinawa Prefecture was thoroughly washed, 1800 mL of distilled water at about 70 C. was added thereto, and the mixture was heat treated by placing the mixture in a water bath at about 70 C. for 3 hours. The heat treated product thus obtained was subjected to suction filtration using a Buchner funnel with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and thus a residue was obtained.

(8) 500 g (wet weight) of the residue was weighed, and the residue was dried for 30 minutes at about 60 C. using a dryer (manufactured by Panasonic Corp., product No. EH5101P TurboDry). Thus, 225 g of dried fruit peel was obtained. 100% (v/v) Ethanol in an amount of 2 times the weight of the juice waste was added thereto, and ethanol extraction was carried out for 3 days at room temperature. The extract was subjected to suction filtration using a Buchner funnel provided with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and thus a filtrate was obtained. The filtrate was concentrated and solid-dried, and 13.1 g of a concentrated solid-dried product was obtained (After ethanol extraction (1) in Table 2). The filtrate thus obtained was concentrated with a rotary evaporator, and thus a concentrate was obtained.

(9) A 10-fold amount of a 1% (w/v) aqueous solution of sodium hydroxide was added to the concentrate, and the mixture was stirred for 1 day at room temperature using a stirrer. An insoluble component thus obtained was washed with a double amount of water. The residual insoluble component was eluted with a 5- to 10-fold amount of 100% (v/v) ethanol. Subsequently, the ethanol-eluted component was treated to separate a precipitate by filtration using a Buchner funnel. The contents of nobiletin and tangeretin in 76.0 mg of a composition containing nobiletin and tangeretin obtained by concentrating and solid-drying the filtrate were measured by HPLC, and as indicated in Table 2, the contents were 43.9 mg and 26.8 mg, respectively, while the percentage content was about 93% by weight. In the following Table 2, the contents, percentage contents and recovery ratios of nobiletin and tangeretin were determined in the same manner as in Example 1 described above.

(10) TABLE-US-00002 TABLE 2 Component Nobiletin Tangeretin Percentage Percentage Recovery Content content Content content ratio Step (mg) (wt %) (mg) (wt %) (%) After ethanol 368 2.8 172 1.3 108 extraction (1) After ethanol 43.9 57.8 26.8 35.3 14.1 elution after alkali treatment (2)

Example 3

(11) 50 g (wet weight) of a pomace of Taiwan tangerine was weighed, and the pomace was dried for 30 minutes at about 60 C. using a dryer (manufactured by Panasonic Corp., product No. EH5101P TurboDry). Thus, 15 g of dried fruit peel was obtained. 100 mL of distilled water at about 70 C. was added to the dried fruit peel thus obtained, the mixture was placed in a water bath at about 70 C., and heating and extraction was carried out for 3 hours. An extract thus obtained was subjected to suction filtration using a Buchner funnel provided with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and thus a residue was obtained.

(12) The residue thus obtained was dried, 100% (v/v) ethanol in an amount of 2 times the weight of the juice waste was added thereto, and ethanol extraction was carried out for 3 days at room temperature. The extract was subjected to suction filtration using a Buchner funnel provided with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and thus a filtrate was obtained (After ethanol extraction (1) in Table 3). The filtrate thus obtained was concentrated with a rotary evaporator, and thus 1.15 g of a concentrate in a solid-dry state was obtained. 10% (v/v) Methanol in an amount of 2 times the weight of the concentrate thus obtained was added to the concentrate, the concentrate was dissolved therein, and solution was centrifuged at 415 g for 30 minutes at room temperature. Thus, the concentrate was separated into a 10% methanol-insoluble component and a soluble component.

(13) 50% (v/v) Ethanol in a one-fold amount was added to the 10% (v/v) methanol-insoluble component thus obtained, and the mixture was centrifuged at 410 g for 30 minutes at room temperature. Furthermore, the mixture was divided into an insoluble component and a soluble component. The soluble component was concentrated for 30 minutes at 40 C., a 1% (w/v) aqueous solution of sodium hydroxide in a 10-fold amount was added thereto, and the mixture was stirred for 6 days at room temperature using a stirrer. Subsequently, the mixture was subjected to suction filtration using a Buchner funnel provided with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and thus a precipitate and a filtrate were separated by filtration. The precipitate thus obtained was washed with a double amount of water, and subsequently, the precipitate was eluted with a 5- to 10-fold amount of 100% (v/v) ethanol. Subsequently, the ethanol-eluted component was treated to separate a precipitate by filtration using a Buchner funnel. The filtrate thus obtained was concentrated and solid-dried, and thus 28.4 mg of a purification product containing nobiletin and tangeretin at high concentrations was obtained. The contents of nobiletin and tangeretin in the purification product were measured by HPLC, and as indicated in Table 3, the contents were 14.1 mg and 11.2 mg, respectively, while the percentage content was about 89% by weight. In the following Table 3, the contents, percentage contents and recovery ratios of nobiletin and tangeretin were determined in the same manner as in Example 1 described above.

(14) TABLE-US-00003 TABLE 3 Component Nobiletin Tangeretin Percentage Percentage Recovery Content content Content content ratio Step (mg) (wt %) (mg) (wt %) (%) After ethanol 32.2 2.8 17.2 1.5 98.8 extraction (1) After ethanol 14.1 49.7 11.2 39.4 50.6 elution after alkali treatment (2)

(15) As described above, fractions containing nobiletin and tangeretin at high concentrations were obtained. Since the fractions thus obtained contain nobiletin and tangeretin at concentrations several times higher than those of fractions that have been produced hitherto, these compounds can be conveniently produced. Furthermore, when the high-concentration fractions obtained according to the method of the present invention are used, superiority is increased in view of cost on the occasion of producing these compounds and analogues thereof.

Example 4

(16) Powders containing nobiletin and tangeretin at high concentrations of Lots 1 to 3 described below were obtained.

(17) [Lot 1]

(18) 70 kg of a dried pomace of Taiwan tangerine was subjected to extraction for 2 hours at 60 C. using 450 L of 30% (v/v) ethanol. Extracts after the passage of 1 hour and 2 hours from the extraction, and the extract concentrated thereafter were sampled, and then the samples were filtered through cartridge filters (retention particle size: 10 m). Subsequently, the filtrates were concentrated, and thus the amount of the solution was decreased to 130 L. A 2% (w/v) aqueous solution of sodium hydroxide in the same amount as the amount of the solution (130 L) was added thereto, and the solution was stirred overnight at room temperature. Thereafter, the solution was centrifuged, and 319 g (wet weight) of a precipitate powder was obtained. An operation of immersing the powder thus obtained in water and then filtering the powder was repeated twice. The powder was washed with water and filtered again, and then the residue on the filter paper was immersed in ethanol. The residue was suction filtered, and an ethanol extract thus obtained was concentrated. Thus, 62.5 g of a high nobiletin- and tangeretin-containing powder (percentage content of nobiletin: 42.8 wt %, and percentage content of tangeretin: 45.9 wt %) was obtained. The results are presented in Table 4.

(19) TABLE-US-00004 TABLE 4 Component Nobiletin Tangeretin Total Percentage Percentage Recovery Step amount content Content content Content ratio Extract, after concentration (g) 2340 g 5.5 wt % 128.7 g 3.5 wt % 81.9 g 60.1% NaOH treatment, before drying 319 g 26.8 g 28.6 g 15.8% NaOH treatment, after drying 92.5 g 28.9 wt % 26.8 g 30.9 wt % 28.6 g 15.8% After washing with water EtOH eluate 62.5 g 42.8 wt % 26.8 g 45.9 wt % 28.6 g 15.8%

(20) [Lot 2]

(21) 55 kg of a dried pomace of Taiwan tangerine was subjected to extraction for 1 hour at 60 C. using 450 L of 30% (v/v) ethanol. The extract was left to stand overnight at room temperature, and then was filtered through a cartridge filter (retention particle size: 10 m). Subsequently, the filtrate was concentrated, and the amount of the solution was decreased to 80 L. A 2% (w/v) aqueous solution of sodium hydroxide in the same amount as that of the solution was added thereto, and the solution was stirred while kept cold at 6 C. Subsequently, the solution was centrifuged, and 1534 g of a sodium hydroxide-treated product was obtained. 1294 g of the sodium hydroxide-treated product thus obtained was washed with water. Thereafter, centrifugation was carried out, and thus the product was separated into a supernatant and a precipitate. The precipitate was freeze-dried, and then was washed with water, and 92.6 g of a powder was obtained. The powder was washed with water again, and then was dissolved in ethanol, and suction filtration was carried out. The ethanol-eluted component was concentrated, and thus 58.2 g of a high nobiletin- and tangeretin-containing powder (percentage content of nobiletin: 54.2 wt %, and percentage content of tangeretin: 36.0 wt %) was obtained. The recovery ratio was 24.3%.

(22) [Lot 3]

(23) 55 kg of a dried pomace of Taiwan tangerine was subjected to extraction for 1 hour at 60 C. using 450 L of 30% (v/v) ethanol. The extract was left to stand overnight at room temperature, and then was filtered through a cartridge filter (retention particle size: 10 m). Subsequently, the filtrate was concentrated, and the amount of the solution was decreased to 95 L. 5 L of the solution was spray-dried, and to 90 L of the concentrate, the same amount of a 2% (w/v) aqueous solution of sodium hydroxide was added. The solution was stirred while maintained at 20 C. to 25 C. Subsequently, the solution was centrifuged, and 260 g of a sodium hydroxide-treated product was obtained. This sodium hydroxide-treated product was washed with water. Subsequently, centrifugation was carried out, a precipitate was freeze-dried and washed with water, and then 90.7 g of a powder was obtained. The powder was washed again with water, and then was dissolved in ethanol. The resultant was subjected to suction filtration. An ethanol-eluted component was concentrated, and 76.3 g of a high nobiletin- and tangeretin-containing powder (percentage content of nobiletin: 50.2 wt %, and percentage content of tangeretin: 31.2 wt %) was obtained. The recovery ratio was 25.2%.

Example 5

(24) 55 g of a dried pomace of Taiwan tangerine was immersed in 450 ml of 30% (v/v) ethanol, and the mixture was subjected to extraction for 2 hours in a water bath at 70 C. The extract was filtered through a nonwoven fabric. A portion of the extract was concentrated and weighed, and the contents of nobiletin and tangeretin were calculated by performing a HPLC analysis. The same operation was carried out using 40% (v/v), 50% (v/v) and 70% (v/v) ethanol instead of 30% (v/v) ethanol. The recovery ratio was calculated based on 275 mg, which was assumed to be contained in 55 g of the dried pomace. The results are presented in Table 5.

(25) TABLE-US-00005 TABLE 5 Nobiletin Tangeretin Percentage Percentage Recovery Weight content Content content Content ratio 30% 2268 mg 3.9 wt % 89 mg 1.7 wt % 37 mg 46.2% 40% 2525 mg 3.2 wt % 81 mg 1.5 wt % 38 mg 43.1% 50% 1770 mg 4.0 wt % 71 mg 2.2 wt % 39 mg 39.9% 70% 1831 mg 3.9 wt % 71 mg 2.1 wt % 38 mg 39.9%

Example 6

(26) 55 kg of a dried pomace of Taiwan tangerine was subjected to extraction for 6 hours at 60 C. using 450 L of 30% (v/v) ethanol. The extract was left to stand overnight at room temperature, and then was filtered through a cartridge filter (retention particle size: 10 m). Subsequently, the filtrate was concentrated, the amount of the solution was decreased to 130 L, and this was used as a Taiwan tangerine extract. To 5 g of a freeze-dried powder of this Taiwan tangerine extract (containing 195 mg (3.9% by weight) of nobiletin and 100 mg (2.0% by weight) of tangeretin), 30 ml of a 1% (w/v) aqueous solution of sodium hydroxide was added, and a Taiwan tangerine alkali-treated product was obtained. This alkali-treated product was stirred by rotation for 16 hours, and then was centrifuged. Thus, precipitate 1 was obtained. This precipitate 1 was washed with water and then centrifuged, and precipitate 2 was obtained. This process was performed until the supernatant became neutral. 100% (v/v) Ethanol was added to a product (1.1 g) obtained by drying the precipitate finally obtained, and the mixture was centrifuged. A filtrate thus obtained was concentrated, and thus 344 mg of a powder was obtained. This powder contained 159 mg (46.3% by weight) of nobiletin and 87 mg (25.3% by weight) of tangeretin. According to the present method, 80% or more of nobiletin and tangeretin contained in the freeze-dried powder could be recovered.

Example 7

(27) 55 kg of a dried pomace of Taiwan tangerine was subjected to extraction for 6 hours at 60 C. using 450 L of 30% (v/v) ethanol. The extract was left to stand overnight at room temperature, and then was filtered through a cartridge filter (retention particle size: 10 m). Subsequently, the filtrate was concentrated, the amount of the solution was decreased to 130 L, and this was used as a Taiwan tangerine extract. To 4.5 g of a concentrated and solid-dried product of this Taiwan tangerine extract (containing 175 mg (3.9% by weight) of nobiletin and 90 mg (2.0% by weight) of tangeretin), 30 ml of a 1 w/v % aqueous solution of sodium hydroxide was added, and a Taiwan tangerine alkali-treated product was obtained. This alkali-treated product was stirred by rotation for 16 hours, and then was centrifuged. Thus, precipitate 1 was obtained. This precipitate 1 was washed with water and then centrifuged, and precipitate 2 was obtained. This process was performed until the supernatant became neutral. 100% (v/v) Ethanol was added to a product (760 mg) obtained by drying the precipitate finally obtained, and the mixture was centrifuged. A filtrate thus obtained was concentrated, and thus 344 mg of a powder was obtained. The filtrate contained 159 mg (44.2% by weight) of nobiletin and 87 mg (22.7% by weight) of tangeretin. According to the present method, 60% or more of nobiletin and tangeretin contained in the concentrate could be recovered.

Reference Example 1

(28) 589 g (wet weight) of the leaves of Taiwan tangerine were weighed, and the leaves were dried for 16 hours at about 80 C. using a drying machine (TOKYO RIKAKIKAI CO., LTD., WFO-1001 SD). Thus, 218 g of dried leaves were obtained. To 5 g of the dried leaves thus obtained, 100 mL of distilled water at about 70 C. was added thereto, the mixture was placed in a water bath at about 70 C., and heating and extraction was carried out for 3 hours. The extract thus obtained was subjected to suction filtration using a Buchner filter provided with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and thus a residue was obtained.

(29) The residue thus obtained was dried, and 30% (v/v) ethanol in an amount of 2 times the weight of the residue was added thereto. Ethanol extraction was carried out for 3 days at room temperature. The extract was subjected to suction filtration using a Buchner funnel provided with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and a filtrate was obtained. The filtrate thus obtained was concentrated with a rotary evaporator, and a concentrate in a solid-dry state was obtained. Water and ethyl acetate in amounts equal to the weight of the concentrate thus obtained were added to the concentrate to thereby dissolve the concentrate, and partition was carried out. The ethyl acetate-soluble component was concentrated, and an extract having a nobiletin percentage content of 24.4 wt % and a tangeretin percentage content of 11.2 wt % was obtained.

Reference Example 2

(30) 100 mL of distilled water at about 70 C. was added to 5 g of dried leaves of Taiwan tangerine, the mixture was placed in a water bath at about 70 C., and heating and extraction was carried out for 3 hours. The extract thus obtained was subjected to suction filtration using a Buchner funnel provided with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and a residue was obtained.

(31) The residue thus obtained was dried, and 100% (v/v) ethanol in an amount of 2 times the weight of the residue was added thereto. Ethanol extraction was carried out for 3 days at room temperature. The extract was subjected to suction filtration using a Buchner funnel provided with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and a filtrate was obtained. The filtrate thus obtained was concentrated with a rotary evaporator, and a concentrate in a solid-dry state was obtained. Water and ethyl acetate in amounts equal to the weight of the concentrate thus obtained were added to the concentrate to thereby dissolve the concentrate, and partition extraction was carried out. The ethyl acetate-soluble component was concentrated, and an extract having a nobiletin percentage content of 6.9 wt % and a tangeretin percentage content of 5.2 wt % was obtained.

Reference Example 3

(32) 100 mL of distilled water at about 70 C. was added to 5 g of dried leaves of Taiwan tangerine, the mixture was placed in a water bath at about 70 C., and heating and extraction was carried out for 3 hours. The extract thus obtained was subjected to suction filtration using a Buchner funnel provided with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and a residue was obtained.

(33) The residue thus obtained was dried, and 100% (v/v) ethanol in an amount of 2 times the weight of the residue was added thereto. Ethanol extraction was carried out for 3 days at room temperature. The extract was subjected to suction filtration using a Buchner funnel provided with a filter paper (manufactured by Advantec MFS, Inc., No. 131) having a retention particle size of 3 m spread thereon, and a filtrate was obtained. The filtrate thus obtained was concentrated with a rotary evaporator, and a concentrate in a solid-dry state was obtained. Water and ethyl acetate in amounts equal to the weight of the concentrate thus obtained were added to the concentrate to thereby dissolve the concentrate, and partition was carried out. The ethyl acetate-soluble component was concentrated, and an extract having a nobiletin percentage content of 6.9 wt % and a tangeretin percentage content of 5.2 wt % was obtained. In the same manner, extraction was carried out using 30% (v/v) ethanol, 50% (v/v) ethanol, and 70% (v/v) ethanol, respectively, instead of 100% (v/v) ethanol. The results are presented in Table 6.

(34) TABLE-US-00006 TABLE 6 Ethanol Weight of ethyl concentration acetate extract Percentage content (%) (%) (mg) Nobiletin Tangeretin 30 82 24.4 11.2 50 122 18.0 15.5 70 174 13.2 7.9 100 361 6.9 5.2

(35) From the above results, it is understood that when the ethanol concentration increases, the weight of the ethyl acetate extract is increased; however, the contents of nobiletin and tangeretin are larger when 30% (v/v) ethanol or 50% (v/v) ethanol is used, and the extraction efficiency is high when ethanol at these concentrations is used. As described above, fractions containing nobiletin and tangeretin at high concentrations were obtained even from the leaves of Taiwan tangerine. Since the fractions thus obtained contain nobiletin and tangeretin at concentrations several times higher compared with the fractions that have been produced hitherto, these compounds can be conveniently produced. Furthermore, when the high concentration fractions obtained by the method of the present invention are used, superiority is increased in view of cost on the occasion of producing these compounds and analogues thereof.

INDUSTRIAL APPLICABILITY

(36) The present invention is useful in the fields of food, pharmaceutical products and cosmetic products, and is particularly useful as a cream preparation, a gel cream preparation and a skin lotion, or from the viewpoint of being incorporable into these products.