JP2002145898A - New glycyrrhetinic acid derivative and sweetener - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low-caloric substance having an excellent degree of sweetness as a sweetener as compared with that of a conventional sweetener. SOLUTION: A new glycyrrhetinic acid derivative (including the form of a salt) such as 3β-O-(L-seryl-α-L-aspartyl)glycyrrhetinic acid or 3β-O-(L-seryl-D- seryl)glycyrrhetinic acid can be used as a new sweetener having excellent properties and can further be used as a substance capable of imparting the sweetness to a product such as a beverage or a food requiring the sweetness in addition to the usability as the sweetener.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel glycyrrhetinic acid derivative, a sweetener containing the same as an active ingredient, and a product such as a sweetened food.

[0002]

2. Description of the Related Art In recent years, obesity due to excessive intake of sugar and various diseases associated therewith have become a problem with the sophistication of dietary habits, and development of a low-calorie sweetener instead of sugar has been desired. Currently, glycyrrhizin is extracted from licorice as a natural high-intensity sweetener, and its sweetness intensity is said to be 170 to 200 times that of sugar, but because of its poor solubility and sustained sweetness, it is a substitute for sugar. The range of use is limited. Enzyme-treated licorice (α-glucosylated glycyrrhizin, etc.) for the purpose of improving taste and physical properties of glycyrrhizin
Alternatively, enzymatically decomposed licorice (such as glycyrrhetinic acid monoglucuronide) has been studied and sweetness intensity has been enhanced, but no fundamental improvement in taste quality has been made (Murakami, Japan Food Science, 59 (1995)). ). On the other hand, attempts have been made to replace the sugar components of neohesperidin dihydrochalcone and stevioside, which are also natural sweet substances, with amino acid components to reduce the persistence of sweetness and improve taste quality (GEDuBois et.al., J.Agric.Fo
od Chem., 29, 1269 (1981), idem, J, Med.Chem., 28, 93 (198
5)), but no practical sweet substance has been found. Under such circumstances, development of a low-calorie sweetener having excellent sweetness and solubility has been demanded.

[0003]

An object of the present invention is to use various readily available glycyrrhetinic acid (aglycone of glycyrrhizin) and an amino acid to obtain 3β-O- of various peptides having excellent sweetness, sweetness and solubility. It is an object of the present invention to provide a glycyrrhetinic acid ester and salts thereof, and a low-calorie sweetener containing these as an active ingredient.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have synthesized various compounds in which two glucuronic acids, which are hydrophilic sites of glycyrrhizin, have been replaced with peptides, and reduced the degree of sweetness thereof. Examined. As a result, they have found that the compound represented by the following general formula (1) is excellent as a sweetener, and have completed the present invention based on this finding. That is, the present invention resides in glycyrrhetinic acid derivatives (including those in the form of salts) represented by the following general formulas (1), (2) and (3) and products containing the same, such as sweeteners and foods.

[0005]

Embedded image In the general formula (1), R ₁ is a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or a hydroxyl group, a carbamoyl group, a mercapto group, or a methylthio group as a substituent. Represented by a linear or branched alkyl group having 1 to 4 carbon atoms, which is substituted with a group selected from the group consisting of amino group, guanidino group, imidazoyl group, phenyl group, hydroxyphenyl group and indolyl group. You. R
₂ represents a hydrogen atom or a linear or branched C 1
Or a group selected from the group consisting of a hydroxyl group, a carboxyl group, a carbamoyl group, a mercapto group, a methylthio group, an amino group, a guanidino group, an imidazoyl group, a phenyl group, a hydroxyphenyl group, and an indolyl group. And a peptide in which 2 to 4 amino acid residues having a linear or branched alkyl group having 1 to 4 carbon atoms in the side chain are substituted. Here, when R ₂ is a peptide, the amide bond (peptide bond) may be any of α, β, γ, δ, or ε bond. Here, R ₂ and an amino group (NH)
Represents that it is an amide bond (CO-NH).
However, _{R 1} is a hydrogen atom or a benzyl group, at the same time _{R 2}
Is an aspartic acid residue linked by an α-carbonyl group.

Embedded image

Embedded imageIn the above general formulas (2) and (3), R₃, R₄, R₅as well as
R₆Is a hydroxyl group, a hydrogen atom, or a linear or branched
As a C1-C4 alkyl group or a substituent
Hydroxyl group, carboxyl group, carbamoyl group, mercapto
Group, methylthio group, amino group, guanidino group, imidazo
Yl, phenyl, hydroxyphenyl, indoli
Linear group substituted with a group selected from the group consisting of
Or a branched alkyl group having 1 to 4 carbon atoms in the side chain
Amino acid residues or condensation of 2 to 4 of these amino acid residues
It is represented by the following peptide. Where R₃, R₄, R₅Passing
And R₆Is a peptide, the amide bond of which is α, β,
Any of γ, δ, and ε bonds may be used. n and m are 1
Or 2 is represented. Where R₃And R₅And carbonyl group
(C = O) or R₄And R ₆And amino group
The bond with (NH) is an amide bond (NH-CO or CO
-NH). Where R₃Are hydroxyl groups at the same time
To R₄Is a hydrogen atom, and R₅Is a hydroxyl group and R₆But water
It is excluded if it is an elementary atom.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The novel glycyrrhetinic acid derivatives of the present invention include the compounds represented by the above general formulas (1), (2) and (3), and further include those in the form of a salt thereof. The amino acid constituting the above derivative may be any of L-form, D-form and DL-form.

The compounds of the present invention include the following inventions as preferred compound forms.

[1] A compound represented by the above general formula (1). However, in the general formula (1), R ₁ is a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or a hydroxyl group, a carbamoyl group, a mercapto group as a substituent, A straight-chain or branched C1-C4 alkyl group substituted by a group selected from the group consisting of methylthio, amino, guanidino, imidazoyl, phenyl, hydroxyphenyl and indolyl groups; is there.

R ₂ represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or a hydroxyl group, a carboxyl group, a carbamoyl group, a mercapto group, a methylthio group, an amino group, Amino acid residues having a linear or branched C1-C4 alkyl group in the side chain substituted with a group selected from the group consisting of guanidino group, imidazoyl group, phenyl group, hydroxyphenyl group and indolyl group. It is a peptide in which 2 to 4 groups or these amino acid residues are condensed.

Here, when R ₂ is a peptide, the amide bond (peptide bond) is any of α, β, γ, δ, or ε bond.

[0011] However, where the binding of _{R 2} and amino group (NH) is an amide bond (CO-NH).

However, the case where R ₁ is a hydrogen atom or a benzyl group and R ₂ is an aspartic acid residue bonded with an α-carbonyl group at the same time is excluded.

[2] Compounds represented by the above general formulas (2) and (3). However, in the above general formulas (2) and (3), R
₃ , R ₄ , R ₅ and R ₆ are a hydroxyl group, a hydrogen atom, or a linear or branched alkyl group having 1 to 4 carbon atoms, or a hydroxyl group, a carboxyl group, a carbamoyl group, or a mercapto group as a substituent. A straight-chain or branched C1-C4 alkyl group substituted with a group selected from the group consisting of, methylthio, amino, guanidino, imidazoyl, phenyl, hydroxyphenyl, and indolyl groups Or a peptide in which 2 to 4 amino acid residues are condensed.

Here, R ₃ , R ₄ , R ₅ and R ₆
Is a peptide, the amide bond (peptide bond) is any of α, β, γ, δ, or ε bond and the like.

Here, the bond between R ₃ and R ₅ and a carbonyl group (C ＝ O) or the bond between R ₄ and R ₆ and an amino group (NH) is an amide bond (NH—CO or CO 2).
-NH).

N and m are 1 or 2.

However, the case where R ₃ is a hydroxyl group and R ₄ is a hydrogen atom at the same time, and R ₅ is a hydroxyl group and R ₆ is a hydrogen atom at the same time is excluded.

[3] The compound of [1], wherein R ₁ is a hydroxymethyl group and R ₂ is a serine residue.

[4] The compound of [1], wherein R ₁ is a hydroxymethyl group and R ₂ is a seryl serine residue.

[5] The compound according to [2], wherein R ₃ is a hydroxyl group, n is 1, and R ₄ is a serine residue.

[6] The compound according to [2], wherein R ₃ is a hydroxyl group, n is 2, and R ₄ is a serine residue.

[7] The compound according to [2], wherein R ₃ is an aspartic acid residue, n is 1, and R ₄ is a hydrogen atom.

[8] The compound according to [2], wherein R ₅ is an aspartic acid residue, m is 1, and R ₆ is a hydrogen atom.

[9] The compound according to [2], wherein R ₅ is a hydroxyl group, m is 1, and R ₆ is a serine residue.

[10] A sweetener or a sweetened food or other product comprising the derivative of the present invention as an active ingredient. In addition, carriers or extenders for sweetening agents may be included.

[11] Products requiring sweetness (food and beverages,
A method for imparting sweetness by including (mixing, adding) the derivative of the present invention in pharmaceuticals and oral hygiene products).

The salts of the present invention contained in the derivatives of the present invention include, for example, salts with alkali metals such as sodium and potassium, salts with alkaline earth metals such as calcium and magnesium, ammonium salts with ammonia, lysine and arginine And salts with inorganic acids such as hydrochloric acid and sulfuric acid, salts with organic acids such as citric acid and acetic acid and saccharin, acesulfame (aces)
ulfame), cyclamic acid
cid), glycyrrhizic (glycyrrhizic)
and salts with other sweeteners such as acid), which are also included in the derivatives of the present invention as described above.

The glycyrrhetinic acid derivative of the present invention comprises a glycyrrhetinic acid in which the carboxyl group is protected as a benzyl ester and an amino group, a carboxyl group, and a side chain functional group which are suitable for use in peptide synthesis. Obtained by condensation with a peptide protected with a butoxycarbonyl group, a benzyl group, a t-butyl group, etc.) and then removing the protecting group by a deprotection method generally used in peptide synthesis such as catalytic reduction or acid hydrolysis. be able to. Alternatively, after condensing glycyrrhetinic acid in which a carboxyl group is protected as a benzyl ester with an amino acid in which an amino group is protected by a t-butoxycarbonyl group, the t-butoxycarbonyl group is removed by acid hydrolysis. The compound of the present invention can be obtained by removing all protecting groups by an appropriate deprotection method after condensation with an amino acid or peptide having the compound, but the synthesis method of the compound of the present invention is not limited thereto.

As a result of a sensory test, the derivative of the present invention, that is, the compound of the present invention and the salt thereof were found to have a sweetness similar to sugar and a half to 5 times that of glycyrrhizic acid-ammonium salt.
It turned out to have twice the sweetness. Furthermore, the compounds of the present invention have improved solubility in water as compared to glycyrrhizin, and this tendency is remarkable in derivatives having a serine residue. In particular, the tripeptide derivative of serine was dissolved at a practical level for imparting sweetness to neutral water without adjusting the pH with ammonia water or the like.

Table 1 shows the structures and the results of sensory tests on some of the synthesized glycyrrhetinic acid derivatives (shown by the following general formula (4)).

[0031]

Embedded image

[0032]

[Table 1]

When the derivative of the present invention (including the compound of the present invention and a salt thereof) is used as a sweetening agent, it may be used in combination with another sweetening agent as long as there is no particular hindrance. Of course.

When the derivative of the present invention is used as a sweetener, a carrier and / or a bulking agent may be used as necessary. For example, a carrier or a bulking agent for a conventionally known or used sweetener is used. Can be used.

Although the derivative of the present invention can be used as a sweetener or a sweetener component, products such as foods which need to impart sweetness further, such as confectionery, chewing gum, hygiene products, cosmetics, pharmaceuticals and non-human It can be used as a sweetener for various products such as animal products. Furthermore, as a form of a product containing the derivative of the present invention and having a sweet taste,
In addition, the derivative of the present invention can be used in a method of imparting sweetness to the product which needs to impart sweetness, and the method of use and the like can be according to a conventional method or other known methods.

[0036]

The present invention will be described below in detail with reference to examples. The scope of the present invention is not limited to the scope of the following embodiments.

Incidentally, the NMR spectrum was measured by Varian.
The MS spectrum was measured with a Thermo Quest TSQ700 by Gemini-300 (300 MHz).

The degree of sweetness is determined by dissolving the derivative in dilute aqueous ammonia and adding 5% of glycyrrhizic acid-ammonium salt.
It was determined in comparison with a sucrose equivalent solution.

Example 1 Synthesis of 3β-O- (L-seryl-α-L-aspartyl) glycyrrhetinic acid (Compound No. 1) 1.12 g of glycyrrhetinic acid 30-benzyl ester
(2.0 mmol) in 20 ml of methylene chloride,
This solution was kept at 0 ° C. N-tert-butoxycarbonyl-L-aspartic acid β-benzyl ester 6
47 mg (2.0 mmol), 24 mg (0.2 mmol) of 4-dimethylaminopyridine and 422 mg (2.2 mmol) of water-soluble carbodiimide hydrochloride were added, and the mixture was added at 0 ° C.
For 1 hour and at room temperature overnight. The obtained reaction solution was concentrated under reduced pressure, and 50 ml of water was added.
2 times, and the organic layer is extracted with a 10% aqueous citric acid solution 50 m
The mixture was washed with 50 ml of a 5% aqueous sodium hydrogen carbonate solution and 50 ml of a saturated saline solution, and dried over anhydrous magnesium sulfate. The magnesium sulfate was removed by filtration, and the filtrate was concentrated under reduced pressure. The residue is separated by preparative thin-layer chromatography (PTL
C), and 1.52 g of 3β-O [(Nt-butoxycarbonyl-β-O-benzyl) -α-L-aspartyl] glycyrrhetinic acid 30-benzyl ester (1.
75 mmol). 1.52 g (1.75 mmol) of this 3β-O-[(Nt-butoxycarbonyl-β-O-benzyl) -α-L-aspartyl] glycyrrhetinic acid 30-benzyl ester was added to 4N-HCl / dioxane 20 ml. After dissolving and stirring for 1 hour, the mixture was concentrated under reduced pressure. The residue was washed with 15 ml of ether and further dried under reduced pressure to obtain 1.41 g (1.75 mmol) of 3β-O [(β-O-benzyl) -α-L-aspartyl] glycyrrhetinic acid 30-benzyl ester hydrochloride. . This 3β-O
[(Β-O-benzyl) -α-L-aspartyl] glycyrrhetinic acid 30-benzyl ester hydrochloride 1.41 g
(1.75 mmol) was dissolved in 20 ml of methylene chloride and the solution was kept at 0 ° C. To this, 576 mg of N-benzyloxycarbonyl-O-benzyl-L-serine was added.
(1.75 mmol) and 0.27 ml of triethylamine
(1.93 mmol), HOBt 260 mg (1.93 mmol)
Mmol) and 369 mg of water-soluble carbodiimide hydrochloride
(1.93 mmol) and the mixture was stirred at 0 ° C. for 1 hour and further at room temperature overnight. The reaction solution was concentrated under reduced pressure, added with 50 ml of water, and extracted twice with 50 ml of ethyl acetate. The organic layer was washed with 50 ml of a 10% aqueous citric acid solution, 50 ml of a 5% aqueous sodium hydrogen carbonate solution and 50 ml of saturated saline, and dried over anhydrous magnesium sulfate. The magnesium sulfate was removed by filtration, and the filtrate was concentrated under reduced pressure. The residue was purified by PTLC to give 3β-O-｛[N-benzyloxycarbonyl-O
-Benzyl-L-seryl]-(β-O-benzyl) -α
1.39 g (1.29 mmol) of -L-aspartyl @ glycyrrhetinic acid 30-benzyl ester were obtained. This 3β-O-{[N-benzyloxycarbonyl-O-benzyl-L-seryl]-(β-O-benzyl) -α-L
1.39 g (1.29 mmol) of aspartyl glycyrrhetinic acid 30-benzyl ester in methanol 20
and 10% palladium on carbon (50% water-containing) 4
00 mg and 1.5 ml of acetic acid were added, and the mixture was stirred at room temperature for 10 hours under a hydrogen atmosphere. After removing the catalyst by filtration, the filtrate was concentrated under reduced pressure, and 380 mg (0.57 mmol, 3β-O- (L-seryl-α-L-aspartyl) glycyrrhetinic acid was added.
(28.3% overall yield) was obtained as a solid.

¹ H NMR (DMSO-d ₆ ) δ: 0.8
2 (s, 6H), 1.05 (s, 3H), 1.07
(S, 3H), 1.10 (s, 3H), 1.37 (s,
3H), 2.73-2.76 (m, 2H), 3.62-
3.84 (m, 2H), 4.45-4.49 (m, 1
H), 4.64-4.67 (m, 1H), 5.41
(S, 1H), 8.89-8.93 (m, 1H) [Only characteristic signals are described].

ESI-MS 673.3 (MH ⁺ )

This compound was dissolved in dilute aqueous ammonia to determine the degree of sweetness. Sweetness (to ammonium glycyrrhizinate) 5 times

Example 2 Synthesis of 3β-O- (D-seryl-α-L-aspartyl) glycyrrhetinic acid (Compound No. 2) N-benzyloxycarbonyl-O-benzyl-L-serine was substituted for N-benzyloxycarbonyl-O-benzyl-L-serine Using 3t-butoxycarbonyl-O-benzyl-D-serine, 3β-
O-{[Nt-butoxycarbonyl-O-benzyl-
D-seryl]-(β-O-benzyl) -α-L-aspartyl diglycyrrhetinic acid 30-benzyl ester was obtained. This was treated with 4N HCl / dioxane and concentrated,
After dissolving in ethyl acetate, the organic layer was washed with a 5% aqueous sodium hydrogen carbonate solution and saturated saline, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to give 3β-O-[(O-benzyl-D-seryl)-. (Β-O-benzyl) -α-L-aspartyl] glycyrrhetinic acid 30-benzyl ester was obtained. This was subjected to catalytic reduction for 17 hours in the same manner as in Example 1 to obtain 3β-O- (D-seryl-α-L-aspartyl) glycyrrhetinic acid as a solid in a total yield of 17.5%.

¹ H NMR (DMSO-d ₆ ) δ: 0.
81 (s, 6H), 1.05 (s, 3H), 1.07
(S, 3H), 1.10 (s, 3H), 1.37 (s,
3H), 2.64-2.76 (m, 2H), 3.45-
3.66 (m, 2H), 4.41-4.47 (m, 1
H), 4.57-4.62 (m, 1H), 5.41.
(S, 1H), 8.49-8.54 (m, 1H) [Only characteristic signals are described].

ESI-MS 673.5 (MH ⁺ )

This compound was dissolved in dilute aqueous ammonia to examine the degree of sweetness. Sweetness (to ammonium glycyrrhizinate) 5 times

Example 3 Synthesis of 3β-O- (L-seryl-D-seryl) glycyrrhetinic acid (Compound No. 3) Nt-butoxycarbonyl-L-aspartic acid β
In the same manner as in Example 1, except that Nt-butoxycarbonyl-O-benzyl-D-serine was used instead of -benzyl ester and deprotection by catalytic reduction was carried out without adding acetic acid. (L-seryl-D-seryl) glycyrrhetinic acid was obtained as a solid in a total yield of 48.2%.

¹ HNMR (DMSO-d ₆ ) δ: 0.
85 (s, 6H), 1.05 (s, 3H), 1.08
(S, 3H), 1.10 (s, 3H), 1.37 (s,
3H), 3.75-3.91 (m, 2H), 4.35-
4.36 (m, 1H), 4.48-4.50 (m, 1
H), 5.19-5.49 (m, 2H), 5.41
(S, 1H), 8.04-8.55 (brs, 2H),
8.83-8.85 (m, 1H) [Only characteristic signals are described].

ESI-MS 645.4 (MH ⁺ )

This compound was dissolved in dilute aqueous ammonia to examine the degree of sweetness. Sweetness (to ammonium glycyrrhizinate) 5 times

Example 4 Synthesis of 3β-O- (L-seryl-α-L-glutamyl) glycyrrhetinic acid (Compound No. 4) Nt-butoxycarbonyl-L-aspartic acid β
3β-O- (L-seryl-α-L-glutamyl) glycyrrhetinic acid was prepared in the same manner as in Example 1 except that Nt-butoxycarbonyl-L-glutamic acid γ-benzyl ester was used instead of -benzyl ester. Total yield 2
Obtained as a solid at 8.8%.

¹ H NMR (DMSO-d ₆ ) δ: 0.
82 (s, 3H), 0.84 (s, 3H), 1.04
(S, 3H), 1.06 (s, 3H), 1.10 (s,
3H), 1.36 (m, 3H), 1.74-1.84.
(M, 2H), 2.73-2.76 (m, 2H), 3.
52-3.77 (m, 2H), 4.32-4.38
(M, 1H), 4.44-4.49 (m, 1H), 5.
41 (s, 1H), 8.68-8.74 (m, 1H)
[Only characteristic signals are described].

ESI-MS 687.3 (MH ⁺ )

This compound was dissolved in dilute aqueous ammonia and the degree of sweetness was examined. Sweetness (to ammonium glycyrrhizinate) 5 times

Example 5 Synthesis of 3β-O- (L-seryl-L-seryl-D-seryl) glycyrrhetinic acid (Compound No. 5) Nt-butoxycarbonyl-L-aspartic acid β
Using Nt-butoxycarbonyl-O-benzyl-D-serine instead of benzyl ester, and Nt-butoxycarbonyl-O-benzyl- instead of N-benzyloxycarbonyl-O-benzyl-L-serine L-serine, N-benzyloxycarbonyl-O-benzyl-
An operation of sequentially condensing L-serine was carried out, and 3β-O- (L-seryl-L-seryl-D- (Ceryl) glycyrrhetinic acid was obtained as a solid in a total yield of 39.3%.

¹ H NMR (DMSO-d ₆ ) δ: 0.
85 (s, 6H), 1.05 (s, 3H), 1.08
(S, 3H), 1.10 (s, 3H), 1.37 (s,
3H), 3.63-3.92 (m, 4H), 4.27-
4.32 (m, 1H), 4.41-4.50 (m, 2
H), 4.49-5.12 (brs, 3H), 5.41.
(S, 1H), 8.20-8.23 (m, 1H), 8.
65-8.68 (m, 1H) [only characteristic signals are described].

ESI-MS 732.7 (MH ⁺ )

This compound was dissolved in dilute aqueous ammonia to determine the degree of sweetness. Sweetness (to ammonium glycyrrhizinate) 5 times

Example 6 N- [α- (3β-O-glycyrrhetinic acid) -β-L-
Aspartyl] -L-aspartic acid (Compound No. 6)
Synthesis of Nt-butoxycarbonyl-L-aspartic acid β
N-benzyloxycarbonyl-L-aspartic acid β-t-butyl ester is used in place of -benzyl ester, and L-aspartic acid α, β- is used in place of N-benzyloxycarbonyl-O-benzyl-L-serine.
N- [α- (3β-O-glycyrrhetinic acid) -β-L was prepared in the same manner as in Example 1 except that dibenzyl ester was used.
-Aspartyl] -L-aspartic acid in a total yield of 22.
Obtained as a solid at 9%.

¹ H NMR (DMSO-d ₆ ) δ: 0.
85 (s, 6H), 1.06 (s, 3H), 1.09
(S, 3H), 1.13 (s, 3H), 1.35 (s,
3H), 1.74-2.12 (m, 2H), 2.42-
2.61 (m, 2H), 2.88-3.02 (m, 2
H), 4.23-4.28 (m, 2H), 4.41-
4.46 (m, 1H), 4.52-4.57 (m, 1
H), 5.42 (s, 1H), 8.52-8.56.
(M, 1H) [Only characteristic signals are described].

ESI-MS 701.6 (MH ⁺ )

This compound was dissolved in dilute aqueous ammonia and the degree of sweetness was examined. Sweetness (to ammonium glycyrrhizinate) 1 /
2 times

Example 7 N- [β- (3β-O-glycyrrhetinic acid) -α-L-
Aspartyl] -L-aspartic acid (Compound No. 7)
Synthesis of L-aspartic acid α, β-dibenzyl ester 56
5 mg (1.80 mmol) was dissolved in 20 ml of methylene chloride and the temperature of the solution was kept at 0 ° C. To this, 582 mg (1.80 mmol) of N-benzyloxycarbonyl-L-aspartic acid β-t-butyl ester, HOB
t268 mg (1.98 mmol) and 380 mg (1.98 mmol) of water-soluble carbodiimide hydrochloride were added,
The mixture was stirred at 0 ° C. for 1 hour and at room temperature overnight. The reaction solution was concentrated under reduced pressure, 50 ml of water was added, and the mixture was extracted twice with 50 ml of ethyl acetate.
and dried over anhydrous magnesium sulfate. The magnesium sulfate was removed by filtration, and the filtrate was concentrated under reduced pressure. The residue is purified by PTLC to give N-benzyloxycarbonyl-β
-O-t-butyl-α-L-aspartyl-L-aspartic acid α, β-dibenzyl ester 828 mg
(1.50 mmol) was obtained. N-benzyloxycarbonyl-β-O-t-butyl-α-L-aspartyl-
L-aspartic acid α, β-dibenzyl ester 82
8 mg (1.50 mmol) was dissolved in 4 N HCl / dioxane 20 ml, and the mixture was stirred at room temperature for 2 hours and concentrated under reduced pressure. The residue was dissolved in 50 ml of ethyl acetate, washed with 50 ml of a 5% aqueous sodium hydrogen carbonate solution and 50 ml of saturated saline, and dried over anhydrous magnesium sulfate. The magnesium sulfate was removed by filtration, and the filtrate was concentrated under reduced pressure to give 754 mg of N-benzyloxycarbonyl-α-L-aspartyl-L-aspartic acid α, β-dibenzyl ester.
(1.34 mmol). 754 mg (1.34) of N-benzyloxycarbonyl-α-L-aspartyl-L-aspartic acid α, β-O-dibenzyl ester
Was dissolved in 20 ml of methylene chloride and the solution was dissolved in 0 ml.
C. To this, 752 mg (1.34 mmol) of glycyrrhetinic acid 30-benzyl ester, 17 mg (0.13 mmol) of 4-dimethylaminopyridine and 283 mg (1.47 mmol) of water-soluble carbodiimide hydrochloride were added, and the mixture was added at 0 ° C. for 1 hour. The mixture was further stirred at room temperature overnight.
The reaction solution was concentrated under reduced pressure, 50 ml of water was added, and 50 ml of ethyl acetate were added.
After extracting twice with 50 ml of a 10% citric acid aqueous solution,
The mixture was washed with 50 ml of a 5% aqueous sodium hydrogen carbonate solution and 50 ml of a saturated saline solution, and dried over anhydrous magnesium sulfate. The magnesium sulfate was removed by filtration, and the filtrate was concentrated under reduced pressure. The residue was purified by PTLC to give N- [N-benzyloxycarbonyl-β- (3β-O-glycyrrhetinic acid 3).
0-benzyl ester) -α-L-aspartyl] -L
-Aspartic acid α, β-dibenzyl ester 726
mg (0.66 mmol) were obtained. N- [N-benzyloxycarbonyl-β- (3β-O-glycyrrhetinic acid 30-benzyl ester) -α-L-aspartyl]-
L-aspartic acid α, β-dibenzyl ester 72
6 mg (0.66 mmol) was dissolved in 20 ml of methanol, and 300 mg of 10% palladium carbon (containing 50% water) was dissolved.
Was added, and reduction was performed at room temperature for 4 hours under a hydrogen atmosphere. The catalyst was removed by filtration, and the filtrate was concentrated under reduced pressure to give N- [β- (3
β-O-glycyrrhetinic acid) -α-L-aspartyl]
-404 mg of L-aspartic acid (0.58 mmol,
(Total yield 32.1%) as a solid.

¹ H NMR (DMSO-d ₆ ) δ: 0.
86 (s, 6H), 1.08 (s, 3H), 1.10
(S, 3H), 1.12 (s, 3H), 1.33 (s,
3H), 1.68-1.82 (m, 2H), 2.40-
2.57 (m, 2H), 2.77-3.02 (m, 2
H), 4.13-4.20 (m, 2H), 4.50-
4.57 (m, 2H), 5.44 (s, 1H), 8.8
3-8.88 (m, 1H) [Only characteristic signals are described].

ESI-MS 701.5 (MH ⁺ )

This compound was dissolved in dilute aqueous ammonia and the degree of sweetness was examined. Sweetness (to ammonium glycyrrhizinate) 1 /
2 times

(Embodiment 8)

Synthesis of 3β-O- (L-seryl-β-L-aspartyl) glycyrrhetinic acid (Compound No. 8) Nt-butoxycarbonyl-L-aspartic acid β
N-t-butoxycarbonyl-L-aspartic acid α-benzyl ester was used in place of -benzyl ester, and 3β-O- (L- (Ceryl-β-L-aspartyl) glycyrrhetinic acid was obtained as a solid in a total yield of 23.2%.

¹ H NMR (DMSO-d ₆ ) δ: 0.
83 (s, 6H), 1.06 (s, 3H), 1.09
(S, 3H), 1.12 (s, 3H), 1.36 (s,
3H), 1.65-1.84 (m, 2H), 2.41-
2.54 (m, 2H), 2.70-2.89 (m, 2
H), 3.74-3.80 (m, 2H), 4.41-
4.50 (m, 1H), 4.57-4.65 (m, 1
H), 5.41 (s, 1H), 8.85-8.91
(M, 1H) [Only characteristic signals are described].

ESI-MS 673.6 (MH ⁺ )

The present compound was dissolved in dilute aqueous ammonia to determine the degree of sweetness. 1x sweetness (to ammonium glycyrrhizinate)

Claims (9)

[Claims] 1. In the following general formulas (1), (2) and (3)
New glycyrrhetinic acid derivative shown in the form of a salt
Including things. ). Embedded imageIn the above general formula (1), R₁Is a hydrogen atom or linear
Or a branched alkyl group having 1 to 4 carbon atoms, or
Represents a hydroxyl group, a carbamoyl group, a mercapto
Group, methylthio group, amino group, guadino group, imidazoi
Phenyl, hydroxyphenyl, indolyl
Linear or substituted with a group selected from the group consisting of groups
Or a branched alkyl group having 1 to 4 carbon atoms. R
₂Is a hydrogen atom or a linear or branched carbon atom
To 4 alkyl groups, or a hydroxyl group,
Boxyl, carbamoyl, mercapto, methylthio
O group, amino group, guanidino group, imidazoyl group,
Consists of nil, hydroxyphenyl and indolyl groups
Linear or branched substituted with a group selected from the group
Amino acid residue having an alkyl group having 1 to 4 carbon atoms in its side chain
Or a peptide in which two to four of these amino acid residues are condensed
It is represented by Where R₂Is a peptide, its amino acid
Bond (peptide bond) is α, β, γ, δ, or ε bond
And so on. Where R₂And amino group (NH)
Represents that it is an amide bond (CO-NH).
Where R₁Is a hydrogen atom or a benzyl group, and R₂
Is an aspartic acid residue linked by an α-carbonyl group
If excluded. Embedded imageEmbedded imageIn the above general formulas (2) and (3), R₃, R₄, R₅as well as
R₆Is a hydroxyl group, a hydrogen atom, or a linear or branched
As a C1-C4 alkyl group or a substituent
Hydroxyl group, carboxyl group, carbamoyl group, mercapto
Group, methylthio group, amino group, guanidino group, imidazo
Yl, phenyl, hydroxyphenyl, indoli
Linear group substituted with a group selected from the group consisting of
Or a branched alkyl group having 1 to 4 carbon atoms in the side chain
Amino acid residues or condensation of 2 to 4 of these amino acid residues
It is represented by the following peptide. Where R₃, R₄, R₅Passing
And R₆Is a peptide, its amide bond (peptide bond
) May be any of α, β, γ, δ, or ε bonds
No. n and m represent 1 or 2. Where R₃And R₅
Or a bond between a carbonyl group (C = O) and R₄And R
₆Is bonded to an amino group (NH) by an amide bond (NH-C
O or CO-NH). Where R₃But
At the same time, R₄Is a hydrogen atom, and R₅Is the same as the hydroxyl group
Sometimes R₆Is excluded when is a hydrogen atom. 2. The derivative according to claim 1, wherein in the formula (1), R ₁ is a hydroxymethyl group and R ₂ is a serine residue. 3. The derivative according to claim 1, wherein in the formula (1), R ₁ is a hydroxymethyl group, and R ₂ is a serylserine residue. 4. In the formula (2), R ₃ is a hydroxyl group, n is 1, R
The derivative according to claim 1, wherein ₄ is a serine residue. 5. In the formula (2), R ₃ is a hydroxyl group, n is 2, R
The derivative according to claim 1, wherein ₄ is a serine residue. 6. The derivative according to claim 1, wherein in the formula (2), R ₃ is an aspartic acid residue, n is 1, and R ₄ is a hydrogen atom. 7. The derivative according to claim 1, wherein in the formula (3), R ₅ is an aspartic acid residue, m is 1, and R ₆ is a hydrogen atom. 8. In the formula (3), R ₅ is a hydroxyl group, m is 1, R
The derivative according to claim 1, wherein ₆ is a serine residue. 9. A sweetener or a sweetened food or other product comprising the derivative according to claim 1 as an active ingredient. In addition, carriers or extenders for sweetening agents may be included.