Patent Application
20100324312
It is an object of the present invention to provide a novel methylated catechin produced by using, as a substrate, epigallocatechin-3-O-gallate, epicatechin-3-O-gallate, or an isomer thereof and to provide a method for manufacturing the same.
In recent years, the number of allergic patients is rapidly increasing due to the changes in living environment. However, allergic diseases require long-term treatment. Therefore, there is a strong demand for allergy alleviating products that have no side effects and can be safely taken on a regular basis. Tea is a beverage favored by many people. Epigallocatechin-3-O-gallate (hereinafter, which may be abbreviated as “EGCG”) is one of the main ingredients of tea and is known to have many physiological functions such as antiallergic activity (Non-Patent Document 1). Recently, catechins such as epigallocatechin-3-O-(3-O-methyl)gallate, and epigallocatechin-3-O-(4-O-methyl)gallate are found to have stronger antiallergic activity than EGCG (Patent Document 1 and Non-Patent Document 2).
Methods for methylating EGCG are described in Non-Patent Document 3 and Patent Documents 2 and 3. However, these methods are based on chemical synthesis and modification. Therefore, with these methods, it is very difficult to specifically methylate the hydroxy groups at positions 3, 4 and 5 of the galloyl group of EGCG. In another known method, a methylated catechin can be biosynthesized in an efficient and site-specific manner using a methylated catechin biosynthetic enzyme. However, this claimed method is for a compound prepared by methylating at least one hydroxy group of EGCG, and only methylation of up to two hydroxy groups is described in the Examples.
Patent Document 1: Japanese Patent Application Laid-Open No. 2000-159670.
Patent Document 2: Japanese Patent Application Laid-Open No. S61-145177.
Patent Document 3: Japanese Patent Application Laid-Open No. 2002-255810.
Non-Patent Document 1: Matsuo, N et al., Allergy 1997, 52, p 58-64.
Non-Patent Document 2: Sano M, Suzuki M, Miyase T, Yoshino K, Maeda-Yamamoto M, J. Agric. Food Chem., 47 (5), 1906-1910 (1999).
Non-Patent Document 3: J. Biochem. 55, p 205 (1964).
The present invention provides a novel methylated catechin having stronger antiallergic activity than conventionally known methylated catechins such as epigallocatechin-3-O-(3-O-methyl)gallate and epigallocatechin-3-O-(4-O-methyl)gallate. The novel methylated catechin of the invention is produced using an enzyme reaction method in which EGCG derived from a natural product is used as a substrate. The invention also provides a method for manufacturing such a methylated catechin.
The present inventors have isolated a methylated catechin synthetic enzyme gene according to the method described in Patent Document 4 (Japanese Patent Application Laid-Open No. 2006-141242). The inventors have obtained the methylated catechin synthetic enzyme by transforming the isolated gene into E. coli.
The present invention is described below.
(1) An epigallocatechin-3-O-gallate derivative represented by the chemical formula I:
(wherein R1 to R6 are each a hydrogen atom or a methyl group, and at least three of R1 to R6 are methyl groups) or an isomer thereof.
(2) An epigallocatechin-3-O-gallate derivative represented by the chemical formula II:
(wherein R1 to R5 are each a hydrogen atom or a methyl group, and at least three of R1 to R5 are methyl groups) or an isomer thereof.
(3) The epigallocatechin-3-O-gallate derivative of (1), wherein the epicatechin-3-O-gallate derivative is epi(3-O-methyl)gallocatechin-3-O-(3,5-O-dimethyl)gallate.
(4) A composition comprising a compound as set forth in any of (1) to (3).
(5) An antiallergic agent comprising a compound as set forth in any of (1) to (3).
(6) A food and beverage product comprising a compound as set forth in any of (1) to (3).
(7) A pharmaceutical or quasi drug comprising a compound as set forth in any of (1) to (3).
(8) A cosmetic comprising a compound as set forth in any of (1) to (3).
(9) A method for manufacturing a compound as set forth in any of (1) to (3), comprising reacting a methylated catechin biosynthetic enzyme with at least one substrate selected from the group consisting of epigallocatechin-3-O-gallate represented by the chemical formula III:
isomers thereof, epicatechin-3-O-gallate represented by chemical formula IV:
and isomers thereof.
With the manufacturing method of the present invention, novel methylated catechins can be efficiently manufactured using catechins such as EGCG as substrates. The novel methylated catechins obtained by the invention have excellent effects such as antiallergic, anticancer, antiobesity, antiarteriosclerosis, antihypertensive, and antimicrobial effects and can be applied to various products such as food and beverage products, pharmaceutical drugs, quasi drugs, and cosmetics.
The novel methylated catechins of the present invention are compounds represented by the chemical formula I wherein at least three of R1 to R6 are methyl groups or compounds represented by the chemical formula II wherein at least three of R1 to R5 are methyl groups.
An enzyme for biosynthesizing methylated catechins (which may be referred to as “methylated catechin biosynthetic enzyme”) is an enzyme that uses epigallocatechin-3-O-gallate, epicatechin-3-O-gallate, or an isomer thereof as a substrate to biosynthesize at least one methylated catechin selected from methylated catechins represented by the chemical formulas (I) and (II) and isomers thereof. Such an enzyme can be obtained by the method described in Japanese Patent Application Laid-Open No. 2006-141242.
An enzyme reaction mixture containing the novel methylated catechin of the invention can be obtained by suspending a methylated catechin biosynthetic enzyme protein in a buffer solution having a pH of 4.5 to 8.5 and preferably 6.5 to 8, adding EGCG and S-adenosyl-L-methionine (SAM) thereto, and allowing the mixture to react at 5 to 60° C. and preferably 20 to 40° C.
A catechin compound containing the novel methylated catechin can be extracted by concentrating the obtained enzyme reaction mixture and using a solvent or the like that can extract the catechin compound. The novel methylated catechin can be manufactured by passing the catechin compound through a column filled with a synthetic adsorbent to adsorb the methylated catechin thereon, washing, and eluting with a suitable solvent. The novel methylated catechin of the invention can also be manufactured and obtained by subjecting the obtained catechin compound to preparative HPLC.
The compounds represented by the chemical formulas I and II and isomers thereof have antiallergic activity and are therefore useful as antiallergic agents.
The food and beverage product, pharmaceutical drug, quasi-drug, and cosmetic of the invention contain at least one compound selected from the group consisting of the compounds represented by the chemical formulas I and II and isomers thereof that are useful as antiallergic agents.
Example of the food and beverage product include: beverages such as soft drinks, carbonated drinks, energy drinks, fruit drinks, and fermented lactic drinks (including concentrated undiluted solutions thereof and powders for preparation of these drinks); frozen desserts such as ice creams, ice sherbets, and ice shavings; noodles such as buckwheat noodles, Japanese wheat noodles, gelatin noodles, dumpling skins, shaomai skins, Chinese noodles, and instant noodles; confectionery products such as candies, chewing gums, chocolates, tablets, snacks, biscuits, jellies, jams, creams, and baked goods; fishery and livestock processed foods such as fish pastes (kamaboko and chikuwa), hams, and sausages; milk products such as processed milk and fermented milk; fat and oil-based foods such as margarine, mayonnaise, shortening, whipped cream, and dressings; seasonings such as sauces and bastes; soups, stews, salads, side and main dishes, and pickles; and other various health foods, nutritional supplementary foods, and special health foods.
Examples of the pharmaceutical and quasi drugs include tablets, liquid medicines, capsules, drinkable preparations, and troches.
Examples of the cosmetic include: basic skin care products such as facial cleansing creams, skin lotions, packs, and skin care lotions; make-up cosmetics such as foundations, lipsticks, and eye shadows; body cosmetics such as nail enamels, soaps, bath additives, sunscreens, and spray deodorants; hair cosmetics such as shampoos, hair rinses, hair conditioners, and hair mousses; hair-skin cosmetics such as hair growth tonics, hair growth stimulants, and hair tonics; and aromatic cosmetics such as perfumes and colognes.
When these products are manufactured, the novel methylated catechin may be added together with generally used auxiliary raw materials and additives.
Examples of the auxiliary raw materials and additives include glucose, fructose, sucrose, maltose, sorbitol, stevioside, rubusoside, corn syrup, lactose, mannite, dextrin, citric acid, sodium citrate, tartaric acid, malic acid, succinic acid, lactic acid, L-ascorbic acid, dl-α-tocopherol, sodium erythorbate, glycerin, propylene glycol, glycerin fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, gum arabic, carrageenan, casein, gelatin, pectin, agar, vitamin C, vitamin Bs, vitamin E, nicotinic acid amide, calcium pantothenate, amino acids, calcium salts, surfactants, food colors, perfumes, and preservatives.
Hereinafter, the present invention will be described in further detail byway of Examples. However, the scope of the invention is not limited to these Examples.
The enzyme reaction was performed using a crude enzyme solution of a methylated catechin biosynthetic enzyme manufactured by the method described in Japanese Patent Application Laid-Open No. 2006-141242. An enzyme reaction mixture (100 mM Tris-HCl (pH 7.4), 0.2 mM MgCl2, 25 μM EGCG, 50 μM SAM, the amount of the crude enzyme solution was one-fifth of the amount of the enzyme reaction mixture) was prepared and allowed to react at 30° C. for 16 hours. Subsequently, HCl was added to the reaction mixture such that the concentration of HCl in the reaction mixture was 0.04N to terminate the reaction. The reaction mixture was placed in a warm bath at 55° C. for 30 minutes and then centrifuged (7,000 rpm×10 minutes), and the supernatant was concentrated using a rotary evaporator. An equal amount of ethyl acetate was added to the concentrated solution, and the mixture was shaken and then centrifuged (7,000 rpm×10 minutes) to collect the organic layer. The collected organic layer was concentrated and dried using a rotary evaporator and then dissolved in 35 (v/v) % methanol. The obtained 35 (v/v) % methanol solution was subjected to measurement using preparative HPLC to afford the product.
The molecular formula of the purified compound was determined by TOF-MS (time-of-flight mass spectrometry), and the structural formula was determined by NMR (nuclear magnetic resonance).
Mobile phase: Solution A—methanol, solution B—0.1 (v/v) % aqueous formic acid solution
10 (v/v) % of solution A(0 min)−>50 (v/v) % of solution A(5 min)
Flow rate: 0.6 mL/min, column temperature: 40° C., injection amount: 5 mL
Ion source: ESI (positive, negative), cone voltage: 30 V, capillary voltage: 2500 V
Ion source temperature: 120° C., desolvation temperature: 300° C., MS scan: m/z 100-1000
A signal of [M+H]+=501 was observed in the positive ion mode measurement, and a signal of [M−H]−=499 was observed in the negative ion mode measurement. Therefore, the integer molecular weight was determined to be 500. From the results of the high resolution mass spectrometry, the molecular formula was determined to be C25H24O11.
The purified compound was dissolved in CD3OD. XWIN-NMR AV 600 (Bruker BioSpin) was used for the NMR measurement, and various NMR spectra (1H, 13C, HSQC, HMBC, and COSY) were measured. The measurement results are shown in Table 1. From the results, the compound was determined to be epi(3-O-methyl)gallocatechin-3-O-(3,5-O-dimethyl)gallate.
13C-NMR δ (ppm)
1H-NMR δ (ppm), J value(Hz)
157.9 a
158.1 a
1′
2′
3′
4′
5′
6′
The conversion efficiency from epigallocatechin-3-O-gallate to epi(3-O-methyl)gallocatechin-3-O-(3,5-O-dimethyl)gallate was determined. An enzyme reaction mixture (100 mM Tris-HCl (pH 7.4), 0.2 mM MgCl2, the amount of the crude enzyme solution was one-fifth of the amount of the enzyme reaction mixture) was prepared. In this case, 10 mg, 20 mg, or 50 mg of SAM and 10 mg of epigallocatechin-3-O-gallate were added to the mixture, and the resultant mixture was allowed to react at 30° C. 5 mL of the reaction mixture was collected 0.25, 0.5, 1, 2, 3, 4, and 8 hours after the start of the reaction, and then HCl was added such that its concentration in the collected reaction mixture was 0.04N to terminate the reaction. 8 mL of ethyl acetate was added to the collected mixture, and the resultant mixture was stirred and centrifuged (3000 pm×5 min) to collect the organic layer. 200 μL of 1% ascorbic acid was added to the organic layer, and the resultant mixture was concentrated under suction. The amount of the produced epi(3-O-methyl)gallocatechin-3-O-(3,5-O-dimethyl)gallate was measured by HPLC. The results showed that the amount of the produced epi(3-O-methyl)gallocatechin-3-O-(3,5-O-dimethyl)gallate increased as the reaction time increased and that the conversion efficiency tended to increase as the amount of the added SAM increased. The changes in conversion efficiency are shown in
The effect of epi(3-O-methyl)gallocatechin-3-O-(3,5-O-dimethyl)gallate was determined based on the histamine release inhibitory activity in mouse mast cells. Epigallocatechin-3-O-gallate and epigallocatechin-3-O-(3-O-methyl)gallate known to have stronger antiallergic activity than epigallocatechin-3-O-gallate were used as comparison substances. BMMC (mouse bone marrow-derived mast cells) were used as the mouse mast cells and cultured in RPMI 1640 medium supplemented with 10% inactivated FBS (fetal bovine serum), 10% D11 culture supernatant (as a source of IL-3), 5 mM sodium glutamate, and 50 μM 2-mercaptoethanol. The cells (1×107 cells/mL) were sensitized with anti-DNP-mouse IgE antibody overnight. On the next day, the resultant cells were suspended in Tyrode's solution and incubated with a test sample for 10 minutes. Then, DNP-HSA (antigen) was added thereto to induce degranulation (20 minutes), and the amount of histamine in the supernatant was measured by liquid chromatography. The antiallergic activity was evaluated based on the relative value with respect to the value for the control (distilled water). More specifically, the lower the relative value, the stronger the antiallergic activity. As shown in
The above results showed that a novel methylated catechin having strong antiallergic activity was obtained.
The novel methylated catechins of the invention (methylated catechins of the chemical formula I wherein at least three of R1 to R6 are methylated and methylated catechins of the chemical formula II wherein at least three of R1 to R5 are methylated) can be efficiently manufactured using, as substrates, catechins such as EGCG with a methylated catechin biosynthetic enzyme. The manufactured novel methylated catechins are excellent in antiallergic activity, and therefore the present invention is quite useful.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-028419 | Feb 2007 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/050685 | 1/21/2008 | WO | 00 | 9/10/2009 |
