JPH0611754B2 - Novel compound having peptidase inhibitory activity, its production method and use - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to prolyl endopeptidase (EC, 3.
4.21.26, Prolyl-endopeptid
a), a novel compound having an enzyme inhibitory activity, a chemical synthesis method thereof, and a prolyl endopeptidase activity inhibitor and a drug containing the same as an active ingredient, particularly the use as an antiamnestic agent. is there.

(Prior Art) Prolyl endopeptidases are substance P and TRH (thyroid stimulating hormone), which are considered to be neurotransmitters.
It is known to act on and inactivate vasopressin, which is thought to be related to neurotensin and memory. On the other hand, Dr. Tsuru and Dr. Yoshimoto, Faculty of Pharmaceutical Sciences, Nagasaki University found that compounds that inhibit prolyl endopeptidase activity prevent experimental amnesia caused by rat scopolamine, and reasoned that prolyl endopeptidase inhibitors are involved in memory consolidation. The results also suggest that prolyl endopeptidase inhibitors could be used for the prevention and treatment of amnesia.

(Technical Problem to be Solved by the Invention) Based on the above findings, the present inventors have conducted research to find a compound having a strong prolyl endopeptidase inhibitory activity and an antiamnestic activity. Further, in order to find a novel compound with sufficiently low toxicity, a compound similar to a natural product is synthesized by combining a highly safe fatty acid as a natural compound, an amino acid and a peptide compound, and represented by the following general formula (I). The present invention has been completed by finding that a novel compound having an anti-prolyl endopeptidase activity has a remarkably excellent action on amnesia.

(Structure of Invention) The N-acylpyrrolidine derivative of the present invention has the general formula (I) (In the formula, n represents an integer of 1 to 12, R ₁ represents a saturated or unsaturated straight-chain hydrocarbon group having 11 to 25 carbon atoms, and the unsaturated carbon chain represents a plurality of carbon atoms. R ₃ represents a lower alkyl ester group, a hydroxymethyl group, or a formyl group of the following formula: —COOR ₄ (wherein R ₄ represents a lower alkyl group), and R ₂ represents methyl. Represents a group, a phenyl group, a hydroxyphenyl group, a carboxyl group, a formyl group, an amino group, a hydroxy group, a hydroxyalkyl group, a thiol group or a methylthio group, each of these groups may be substituted, and R ₅ is a hydrogen atom. Is not represented, or when n represents a number of 3, R ₂ and R ₅ may together be represented as a single bond between carbon and nitrogen.).

In the formula, n as an integer of 1 or more is preferably 1 to 30, and more preferably 1 to 12.

The compound in which R ₂ and R ₅ in formula I are taken together to form a single bond between carbon and nitrogen is represented by the following formula (Ib): It has the structure of.

The compound of the formula (I) of the present invention is greatly different from the conventionally well-known anti-amnestic agent of the piracetam derivative type in that it contains a proline residue and a linear fatty acid chain. Since it is a peptide derivative, its toxicity to the living body is extremely low.

Among the compounds of formula (I), the following compounds are preferable because of their high anti-prolyl endopeptidase activity.
In the following, these compounds may be referred to by the numbers in the cutlet.

The compound of the present invention can be synthesized by a general peptide synthesis method, but is conveniently synthesized by the synthetic method of the present invention described below. The abbreviations have the following meanings.

Z: benzyloxycarbonyl group Boc: tert-butyloxycarbonyl group Pro: proline residue norLeu: Norleucine residue Phe: Phenylalanine residue Met: Methionine residue Lys: Lysine residue Lys (Z): N ^ε -benzyloxycarbonyl lysine residue Glu (Bzl): Glutamic acid-γ-benzyl ester residue Glu (CH ₂ OH): Glu (CHO): OMe: methyl ester group WSCD: N-ethyl-N ', N'-dimethylaminopropylcarbodiimide TEA: triethylamine The compound of the general formula (I) of the present invention can be synthesized as follows.

(1) First, in the general formula (I), R ₃ is a lower alkyl ester group of —COOR ₄ (Ic) or (Id): The compound represented by the general formula: A carboxylic acid chloride represented by: carboxylic anhydride or carboxylic acid, and a compound represented by the general formula (IIa) or (IIb): It can be easily synthesized by a conventional method from a peptide containing a proline residue in which the carboxyl terminus represented by is lower alkyl esterified.

(2) Next, in the general formula (I), R ₃ is —CH ₂ OH.
The group of formula (Ie) or (If): In order to obtain the compound of formula (Ic) or (Id), a compound of formula (Ic) or (Id) can be added to a suspension of tert-butyl alcohol or tetrahydrofuran containing these compounds together with sodium borohydride. It is advisable to add methanol dropwise.

(3) Further, using a sulfur trioxide-pyridine complex as an oxidizing agent from the compound represented by the general formula (Ie) or (If), the general formula (Ig) or (Ih): The compound of the present invention represented by is synthesized. Dimethyl sulfoxide was used as the solvent, the reaction temperature was room temperature, and the reaction time was 1
It's about time.

Next, the present invention will be described in more detail based on Examples and Reference Examples.

Reference Example Synthesis of Starting Material Represented by Formula (II) (a) H-Phe-Pro-OMe Z-Phe-OH (1 eq), Pro-OMe Hydrochloride (1 eq) and TEA (1 eq) are dried. Dissolve in methylene chloride and add WSCD (1 eq) under permanent cooling. After stirring at room temperature for 20 hours, the reaction solution is washed with 1N hydrochloric acid, water, saturated aqueous sodium hydrogen carbonate, water, and saturated saline, and dried over anhydrous magnesium sulfate. The residue obtained by distilling off the solvent under reduced pressure is purified by medium pressure column chromatography using silica gel. The obtained Z-Ala-Pro-OMe was dissolved in ethanol (1 equivalent), boron trifluoride-ether complex (1 equivalent) and palladium carbon (small amount) were added to remove the Z group by catalytic reduction, and the solvent was added. Is distilled off under reduced pressure to obtain the desired product.

Instead of Z-Phe-OH in the above (a), (a) Z-M
By using et-OH and (a) Z-nolLeu-OH, (a ′) H-Met-Pro-O, respectively.
Me, (i ') H-norLeu-Pro-OMe can be obtained (oil compound).

(B) H-Lys (Z) -Pro-OMe.trifluoroacetate Boc-Lys (Z) -OH (1 equivalent), Pro-OM
e Hydrochloride (1 eq) and TEA (1 eq) are dissolved in dry methylene chloride and WSCD (1 eq) is added under ice cooling. After stirring at room temperature for 20 hours, the reaction solution was added with 1N hydrochloric acid,
Wash with water, saturated aqueous sodium hydrogen carbonate, water, and saturated brine, and dry over anhydrous magnesium sulfate. The residue obtained by distilling off the solvent under reduced pressure is purified by medium pressure column chromatography using silica gel. Obtained Boc-Lys (Z) -Pr
Dissolve o-OMe (1 eq) in dry methylene chloride, add excess trifluoroacetic acid and stir (about 6 hours).
The solvent is distilled off under reduced pressure to obtain the desired product (oil compound).

In the above (b), B was used instead of Boc-Lys (Z) -OH.
By using oc-Glu (Bzl) -OH, H
-Glu (Bzl) -Pro-OMe trifluoroacetate salt is obtained (oil compound).

(C) H-Pro-Pro-OMe Z-Pro-OH (1 equivalent) and H-Pro-OMe.
The hydrochloride salt (1 eq) and TEA (1 eq) are dissolved in dry methylene chloride and WSCD (1 eq) is added under ice cooling.
After stirring at room temperature for 20 hours, the reaction solution was added with 1N hydrochloric acid, water,
Wash with saturated aqueous sodium hydrogen carbonate, water, and saturated brine, and dry over anhydrous magnesium sulfate. The residue obtained by distilling off the solvent under reduced pressure is purified by medium pressure column chromatography using silica gel. The obtained Z-Pro-Pro-OMe is (1
(Equivalent) dissolved in ethanol, boron trifluoride-ether complex (1 equivalent) and palladium carbon (small amount) are added, the Z group is removed by catalytic reduction in a hydrogen atmosphere, and the solvent is evaporated under reduced pressure to give the desired product as an oil. Obtained as a compound. All the desired compounds can be obtained in the form of oil.

As a result of investigating the efficacy of the present compound for inhibiting the decomposition of Z-glycyl-prolyl-β-naphthylamide by prolyl endopeptidase, a large anti-prolyl endopeptidase activity was shown as shown in the test examples below, and papain Bromelain, trypsin, chymotrypsin,
It showed no inhibitory activity against proteinases such as thermolysin and pepsin.

Further, the present compound thus obtained is novel and has an antiamnestic effect as shown in Examples.

Example 1 a) N-oleoyl-Phe-Pro-OMe (SUA
M1194) H-Phe-Pro-OMe (1 equivalent) and TEA (1 equivalent) were dissolved in dry tetrahydrofuran, and oleic acid chloride (1 equivalent) was added dropwise under ice cooling. After stirring at room temperature for 6 hours, the precipitated hydrochloride of TEA was excessively removed. The solvent was evaporated under reduced pressure, the residue was dissolved in a small amount of ether, washed with 1N hydrochloric acid, saturated saline, saturated aqueous sodium hydrogen carbonate and saturated brine, and dried over anhydrous magnesium sulfate. After concentration under reduced pressure, an ether solution of diazomethane was added to (excess) unreacted oleic acid to form a methyl ester. The solvent was distilled off under reduced pressure and the obtained residue was purified by medium pressure column chromatography using silica gel to obtain the target compound. (Oil compound) By using (a) H-Met-Pro-OMe instead of H-Phe-Pro-OMe in the above (a), (a ') oleoyl-Met-Pro-OMe.
(SUAM1198), (a) H-norLeu-
By using Pro-OMe, (ii) oleoyl-norLeu-Pro-OMe (SUAM1164)
And in the above (a), H-Phe-Pro-OM
Instead of e (1 equivalent) and TEA (1 equivalent), (c)
By using H-Lys (Z) -Pro-OMe.trifluoroacetate (1 eq) and TEA (2 eq), (U ') oleoyl-Lys (Z) -Pro-OMe.
(SUAM1197), (D) H-Glu (Bzl)-
Pro-OMe-trifluoroacetic acid salt (1 equivalent) and TE
By using A (2 equivalents) (d ') oleoyl-
Glu (Bzl) -Pro-OMe (SUAM119
6) can be obtained respectively.

(B) N-oleoyl-Pro-Pro-OMe (SU
AM1195) H-Pro-Pro-OMe (1 equivalent) and TEA (1 equivalent) were dissolved in dry tetrahydrofuran, and oleic acid chloride (1 equivalent) was added dropwise under ice cooling. After stirring at room temperature for 6 hours, the precipitated hydrochloride of TEA was excessively removed. The solvent was evaporated under reduced pressure, the residue was dissolved in a small amount of ether, washed with 1N hydrochloric acid, saturated saline, saturated sodium hydrogen carbonate solution and saturated saline, and dried over anhydrous magnesium sulfate. After concentration under reduced pressure, an ether solution of diazomethane was added to methylate the (excess) unreacted oleic acid. The solvent was distilled off under reduced pressure and the obtained residue was purified by medium pressure column chromatography using silica gel to obtain the target compound. (Oily compound) Example 2 (a) oleoyl _{-Phe-Pro-CH 2 OH (} SU
AM1205) Oleoyl-Phe-Pro-OMe obtained in Example 1.
(SUAM1194) (2 g) and sodium borohydride (600 mg) in tert-butyl alcohol (60 ml)
Dissolve in, and stir with heating (80 ° C.). Next, anhydrous methanol (50 ml) was added dropwise under reflux, and after completion of the dropping, the mixture was heated under reflux with stirring for 2 hours. The reaction solution was returned to room temperature, and water (several ml) was added under ice cooling to inactivate unreacted sodium borohydride. After distilling off methanol and tert-butyl alcohol under reduced pressure, the mixture was extracted with ethyl acetate, the organic layer was washed with saturated saline and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure and the obtained residue was purified by medium pressure column chromatography using silica gel to obtain the target compound (1 g). (Oil compound) In the above (a), oleoyl-Ph was used as a raw material compound.
Instead of e-Pro-OMe, (a) Oleoyl-
By using Met-Pro-OMe, (a ′) oleoyl-Met-Pro-CH ₂ OH (SUAM12
06), (a) oleoyl-norLeu-Pro-
By using OMe (i ') oleoyl-nor
Leu-Pro-CH ₂ OH (SUAM1165),
(C) By using oleoyl-Lys (Z) -Pro-OMe, (U ') oleoyl-Lys (Z)-
Pro-CH ₂ OH (SUAM1207), (d)
By using oleoyl -Glu (Bzl) -Pro-OMe (d ') oleoyl -Glu _(CH 2 O
_H) -Pro-CH 2 OH and (SUAM1209) were obtained, respectively.

(B) oleoyl _{-Pro-Pro-CH 2 OH (} SU
AM1204) Oleoyl-Pro-Pro-OMe obtained in Example 1.
(SUAM1195) (2 g) and sodium borohydride (600 mg) in tert-butyl alcohol (60 ml)
Dissolve in, and stir with heating (80 ° C.). Next, anhydrous methanol (50 ml) was added dropwise under reflux, and after completion of the dropping, the mixture was heated under reflux with stirring for 2 hours. The reaction solution was returned to room temperature, and water (several ml) was added under ice cooling to inactivate unreacted sodium borohydride. After distilling off methanol and tert-butyl alcohol under reduced pressure, the mixture was extracted with ethyl acetate, the organic layer was washed with saturated saline and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure and the obtained residue was purified by medium pressure column chromatography using silica gel to obtain the target compound (1 g) (oil compound).

(A) Oleoyl-Phe-Pro-CHO (SUAM
1212) oleoyl obtained in Example 2 _-Phe-Pro-CH 2 O
H (SUAM1205) (1g) and TEA (800m
g) was dissolved in anhydrous dimethylsulfoxide (8 ml) and sulfur trioxide-pyridine complex (700 m) was stirred.
A solution of g) in dimethylsulfoxide (8 ml) was added. After stirring at room temperature for about 1 hour, the mixture was poured into ice water (100 ml), extracted with ethyl acetate, washed with 10% citric acid solution, saturated saline solution, saturated sodium bicarbonate solution and saturated saline solution, and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure, and the obtained residue was purified by medium pressure column chromatography using silica gel to obtain the target compound. (700 mg) (Oil compound) In the above (a), oleoyl-P was used as a raw material compound.
Instead of _{he-Pro-CH 2 OH,} ( a) by using oleoyl _-Met-Pro-CH 2 OH (A ') oleoyl -Met-Pro-CHO (SUA
M1214), (a) oleoyl-norLeu-P
By using ro-CH ₂ OH (i ′) oleoyl-norLeu-Pro-CHO (SUAM116
6) to (U) oleoyl-Lys (Z) -Pro-C
By using H ₂ OH (w ′) oleoyl-Ly
s (Z) -Pro-CHO (SUAM1216)
(D) oleoyl _{-Glu (CH 2 OH) -Pro-} C
By using H ₂ OH (d ') oleoyl-Gl
u (CHO) -Pro-CHO (SUAM1217) can be obtained.

(B) Oleoyl-Pro-Pro-CHO (SUAM
1215) oleoyl obtained in Example 2 _-Pro-Pro-CH 2 O
H (SUAM1204) (1g) and TEA (800m
g) was dissolved in anhydrous dimethylsulfoxide (8 ml) and sulfur trioxide-pyridine complex (700 m) was stirred.
A solution of g) in dimethylsulfoxide (8 ml) was added. After stirring at room temperature for about 1 hour, the mixture was poured into ice water (100 ml), extracted with ethyl acetate, washed with 10% citric acid solution, saturated saline solution, saturated sodium bicarbonate solution and saturated saline solution, and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure, and the obtained residue was purified by medium pressure column chromatography using silica gel to obtain the target compound (700 mg) (oil compound).

Physicochemical data of the obtained compound are shown in Table 1. Each of the compounds in Table 1 is oily, soluble in CCl ₄ , ether, CHCl ₃ , CH ₂ Cl ₂ , AcOEt, and MeOH, and SUAM1194 is also soluble in benzene.

Example 4 Measurement of anti-prolyl endopeptidase activity The anti-prolyl endopeptidase activity was measured by Yoshimoto (T. Yoshimoto and D. Tsuru, Ag.
r. Biol. Chem. 42, 2417, 1978)
And so on. That is, 0.0025 M Z-glycyl-proline-β-naphthylamide 0.25 ml, 0.
0.99 ml of 1 M phosphate buffer (pH 7.0) and a solution of the anti-prolyl endopeptidase compound of the present invention.
The mixed solution containing 01 ml was heated in a test tube at 37 ° C. for 3 minutes, 0.1 ml of a prolyl endopeptidase solution (0.2 unit / ml) was added, and the mixture was reacted at 35 ° C. for 10 minutes. Then 2.0 m of Triton X-100 (Triton X-100) solution in 1M acetate buffer (pH 4.0).
l so that the final concentration of the surfactant is 10%,
After leaving it at room temperature for 15 minutes, the absorbance (a) at 410 nm was measured.

At the same time, the blind absorbance (b) was measured using only a buffer solution instead of the solution of the anti-prolyl peptidase compound, and the prolyl endopeptidase inhibition rate was calculated by the following formula: [(ba) / b] × 100. The amount required for 50% inhibition [IC ₅₀ ] was calculated. The test results are shown in Table 2.

Example 5 Measurement of Experimental Amnesia Preventive Effect of Scopolamine Using Rat (Intraperitoneal Administration) The antiprolyl endopeptidase compound of the present invention was examined for its effect of preventing long-term memory fixation inhibition by scopolamine. That is, the compound of the present invention was added at 1 mg / kg, 0.
25 mg / kg, 0.1 mg / kg, 0.025 mg /
kg and 0.010 mg / kg, and dissolved in 0.3 ml of physiological saline.
Ster) male rat (100-120 g) was intraperitoneally administered once, and 1 hour after the administration, electric shock (1.7 m)
Passive avoidance learning according to A) was performed, and immediately thereafter, an amount corresponding to 3 mg / kg of scopolamine was intraperitoneally administered.

The results were evaluated by a passive avoidance test at 24 hours and 48 hours after administration of scopolamine and physiological saline in the intraperitoneally-administered group of control animals, test compound administration and scopolamine administration. This was done by comparing the numbers of amnestic and non-amnestic rats for each group of animals that were run together. The test results are shown in Table 3.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryuji Tanaka 1-1-1, Wakayamadai, Shimamoto-cho, Mishima-gun, Osaka Prefecture Suntory Ltd. Applied Microorganism Research Laboratory (56) Reference JP-A-60-188317 (JP, A) ) JP-A-56-59714 (JP, A)

Claims (7)

[Claims] 1. General formula (I): (In the formula, n represents an integer of 1 to 12, R ₁ represents a saturated or unsaturated straight-chain hydrocarbon group having 11 to 25 carbon atoms, and the unsaturated carbon chain represents a plurality of dicarboxylic acids. R ₃ represents a lower alkyl ester group, a hydroxymethyl group, or a formyl group of the following formula: —COOR ₄ (wherein R ₄ represents a lower alkyl group), and R ₂ represents methyl. Represents a group, a phenyl group, a hydroxyphenyl group, a carboxyl group, a formyl group, an amino group, a hydroxy group, a hydroxyalkyl group, a thiol group or a methylthio group, each of these groups may be substituted, and R ₅ is a hydrogen atom. Or n is 3
R ₂ and R ₅ may together represent a single bond between the carbon and the nitrogen. ) The compound represented by. 2. General formula (Ia): (In the formula, n, R ₁ and R ₃ represent the meanings given in claim 1, R ₂ represents a methyl group, a phenyl group,
Hydroxyphenyl group, carboxyl group, formyl group,
It represents an amino group, a hydroxy group, a hydroxyalkyl group, a thiol group or a methylthio group, and each of these groups may be substituted. The compound of Claim 1 represented by these. 3. The general formula (Ib): The compound according to claim ₁ , wherein R ₁ and R ₃ have the meanings given in claim 1. 4. A general formula: (In the formula, R ₁ represents the meaning given by the following formula (I).) A carboxylic acid, a carboxylic acid anhydride, or a carboxylic acid chloride represented by the following general formula (II): (Wherein n, R ₂ , R ₃ and R ₅ have the meanings given by the following formula (I)) and react with a peptide containing a proline residue in which a carboxyl group is lower alkyl esterified. Then, the general formula (I): (In the formula, n represents an integer of 1 to 12, R ₁ represents a saturated or unsaturated straight-chain hydrocarbon group having 11 to 25 carbon atoms, and the unsaturated carbon chain represents a plurality of carbon atoms. R ₃ represents a lower alkyl ester group, a hydroxymethyl group, or a formyl group of the following formula: —COOR ₄ (wherein R ₄ represents a lower alkyl group), and R ₂ represents methyl. Represents a group, a phenyl group, a hydroxyphenyl group, a carboxyl group, a formyl group, an amino group, a hydroxy group, a hydroxyalkyl group, a thiol group or a methylthio group, each of these groups may be substituted, and R ₅ is a hydrogen atom. Or n is 3
R ₂ and R ₅ may together represent a single bond between the carbon and the nitrogen. ) A method for producing an N-acylpyrrolidine derivative represented by: 5. A general formula: (In the formula, R ₁ represents the meaning given by the following formula (I).) And a carboxylic acid anhydride, a carboxylic acid chloride, or a general formula (II): (In the formula, n, R ₂ and R ₅ represent the meaning given by the following formula (I), and R ₃ is the following formula: —COOR ₄ (wherein R ₄
Represents a lower alkyl group. ) Represents a lower alkyl ester group. ) Is reacted with a peptide containing a lower alkyl esterified proline residue represented by the general formula (I): (In the formula, n represents an integer of 1 to 12, R ₁ represents a saturated or unsaturated straight-chain hydrocarbon group having 11 to 25 carbon atoms, and the unsaturated carbon chain represents a plurality of carbon atoms. R ₃ represents a lower alkyl ester group, a hydroxymethyl group, or a formyl group of the following formula: —COOR ₄ (wherein R ₄ represents a lower alkyl group), and R ₂ represents methyl. Represents a group, a phenyl group, a hydroxyphenyl group, a carboxyl group, a formyl group, an amino group, a hydroxy group, a hydroxyalkyl group, a thiol group or a methylthio group, each of these groups may be substituted, and R ₅ is a hydrogen atom. Or n is 3
R ₂ and R ₅ may together represent a single bond between the carbon and the nitrogen. Give N- acyl pyrrolidine derivative represented by), then reduced to R ₃ is a compound which is a -CH 2 _OH in the general formula (I), R ₃ in the general formula (I) is further oxidized to A method for producing an N-acylpyrrolidine derivative in which is -CHO. 6. General formula (I): (In the formula, n represents an integer of 1 to 12, R ₁ represents a saturated or unsaturated straight-chain hydrocarbon group having 11 to 25 carbon atoms, and the unsaturated carbon chain represents a plurality of carbon atoms. R ₃ represents a lower alkyl ester group, a hydroxymethyl group, or a formyl group of the following formula: —COOR ₄ (wherein R ₄ represents a lower alkyl group), and R ₂ represents methyl. Represents a group, a phenyl group, a hydroxyphenyl group, a carboxyl group, a formyl group, an amino group, a hydroxy group, a hydroxyalkyl group, a thiol group or a methylthio group, each of these groups may be substituted, and R ₅ is a hydrogen atom. Or n is 3
R ₂ and R ₅ may together represent a single bond between the carbon and the nitrogen. ) A prolyl endopeptidase activity inhibitor comprising an N-acylpyrrolidine derivative represented by: 7. General formula (I): (In the formula, n represents an integer of 1 to 12, R ₁ represents a saturated or unsaturated straight-chain hydrocarbon group having 11 to 25 carbon atoms, and the unsaturated carbon chain represents a plurality of carbon atoms. R ₃ represents a lower alkyl ester group, a hydroxymethyl group, or a formyl group of the following formula: —COOR ₄ (wherein R ₄ represents a lower alkyl group), and R ₂ represents methyl. Represents a group, a phenyl group, a hydroxyphenyl group, a carboxyl group, a formyl group, an amino group, a hydroxy group, a hydroxyalkyl group, a thiol group or a methylthio group, each of these groups may be substituted, and R ₅ is a hydrogen atom. Or n is 3
R ₂ and R ₅ may together represent a single bond between the carbon and the nitrogen. ) An anti-amnestic agent containing an N-acylpyrrolidine derivative represented by the following as an active ingredient.