JP3101875B2 - Novel tripeptides and activated oxygen inhibitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peptide having the following amino acid sequence, which has utility as a pharmaceutical, and an activated oxygen inhibitor containing such a peptide as an active ingredient. Met-Lys-Met (wherein each symbol representing an amino acid residue is based on a notation commonly used in amino acid chemistry.)

[0002]

2. Description of the Related Art Diseases involving activated oxygen are widely present, such as inflammation such as burns and arthritis, reperfusion injury, side effects of anticancer drugs, radiation injury, peptic ulcer, bacterial shock, cachexia, and autoimmune diseases. I do. Diseases caused by a large amount of activated oxygen generated by activation of neutrophils and macrophages are all covered. Generally, oxygen includes oxygen essential for animals (triplet oxygen molecule: ³ O ₂ ) and radicals (activated oxygen) generated under specific conditions or when the body is upset.
And exists. Radicals can be directly or indirectly (in the form of peroxidation) in cell membranes, intracellular granule membranes, or DNA.
And alters and damages various cell components. The radicals are produced in the body, the type superoxide anion ^(- _O 2 ·), singlet oxygen ⁽¹ _O 2 ·),
There are hydroxyl radicals (.OH) and the like. Among superoxide anion ^(- O 2 _·) causes peroxidation acts on unsaturated fatty acids in cell membranes, the oxidizing power to lipid is said to be higher several thousand times the essential oxygen to animals. Superoxide dismutase as activated oxygen inhibitor (SOD, enzyme number EC 1.15.1.1)
In McCord, J. et al., 1969. M.
& Fridovich, I .; : J. Biol. Che
m. , 244,6049 (1969)] by an enzyme that acts is found, superoxide anion oxygen molecules occurs is one-electron reduction ^(- _{O 2} ·) the disproportionation _{^{2 - O 2 · + 2H +}} → Catalyzes H ₂ O ₂ + O ₂ . When the human body is normal, SOD works to suppress the generation of superoxide anions. This SOD
The activity decreases with aging, that is, the activity decreases from the middle age to the old age, and the increase or decrease of the SOD activity depends on the aging of the living body,
It is also called a barometer of canceration. Such SO
When the D activity decreases, it becomes difficult to suppress the generation of radicals and S
It is necessary to take up an activated oxygen inhibitor which supplements OD or scavenges and removes radicals. On the other hand, the activated oxygen inhibitory action of polypeptides ranging from amino acids to proteins as water-soluble antioxidants inhibits the contact between oxygen molecules and unsaturated fatty acids by encapsulating fats and oils by peptides, and the lipid peroxy radical (LOO) It is thought to suppress the generation of ()), and acts on radicals (LOO) generated during the oxidation of fats and oils (L), such as the antioxidant action of BHA (butylhydroxyanisole) and BHT (dibutylhydroxytoluene). Thus, it is distinguished from the radical scavenging action that stops the chain reaction of oxidation. LOO ・ + AH ₂ → LOOH + AH ・ 2AH ・ → 2AH ₂ + A or LOO ・ + AH ・ → LOO
H + A (AH ₂ ; antioxidant) Against this background, there is no silver bullet for anticancer and antiaging, and today, DNA damage factor, mutation factor, carcinogen, aging factor, etc. must be removed from the environment. Activate,
Studies and studies on activated oxygen inhibitors exhibiting an activated oxygen free radical scavenging action and an antioxidant action have been advanced.

[0003]

In the above-mentioned prior art, SOD as an activated oxygen inhibitor is difficult to produce and the availability of raw materials is limited. Vitamin E, vitamin C, catechins, etc. However, there is a drawback that the activated oxygen inhibitory action is not sufficient in the experiment using, and an activated oxygen inhibitor having a stronger action is demanded. In addition, most of activated oxygen inhibitors exhibiting an activated oxygen free radical scavenging action and an antioxidant action are mostly produced by chemical synthesis, and are derived from natural products using materials from plants and animals. Of these, many are made by using chemical substances that harm the human body during the manufacturing process or by reacting some of the products with the chemical substances. Very little is known about the amino acid sequence and antioxidant power of polypeptides ranging from amino acids to proteins as water-soluble antioxidants, and Yamaguchi et al. [New Food Industry, Vol. 31, pp. 18-22 (1989)] Has a stronger antioxidant activity than amino acids and proteins, and recently Takushoku et al. [Journal of the Japanese Society of Agricultural Chemistry, Vol. 65, pp. 1635-1641 (1991)] reported that three types of anti-oxidants, It only reports oxidized peptides. There is no report that these activated oxygen agents having an active oxygen free radical scavenging action and an antioxidant action are still being developed as pharmaceuticals.

[0004]

Means for Solving the Problems The present inventor has searched for a substance having a pharmacological action from a digested solution of a skipjack proteinase, and has found that the novel tripeptide has a strong activated oxygen inhibitory action. And, they intensively studied to put this peptide into practical use as a medicine. As a result, the present inventors have found that this peptide has an active oxygen free radical scavenging action and an antioxidant action, and is useful as an activated oxygen inhibitor derived from natural products. The present invention is based on such findings. Hereinafter, the present invention will be described in detail. The novel peptide according to the present invention is a novel tripeptide represented by an L-form amino acid sequence represented by the following formula Met-Lys-Met, and is a white powder at room temperature.

[0005] The above-mentioned tripeptide may be chemically synthesized or separated and purified from a digested solution of the skipjack proteolytic enzyme. When chemically synthesizing the novel tripeptide according to the present invention, the C-terminal (carboxyl-terminal side) of the peptide is added to a polymeric solid support by an ordinary peptide synthesis method such as a liquid phase method or a solid phase method. It is preferred that the L-form amino acids corresponding to the amino acid residues are sequentially linked by peptide bonds. Then, the synthetic tripeptide thus obtained is cleaved from the polymeric solid support using trifluoromethanesulfonic acid, hydrogen fluoride, or the like, and then the protecting group on the amino acid side chain is removed. It can be purified by an ordinary method using a system column.

[0006] As described above, the novel tripeptide of the present invention can be separated and purified from the digestion solution of the skipjack proteolytic enzyme. In such a case, for example, the following procedure is performed. it can. The skipjack musculature containing the novel tripeptide is removed and hydrolyzed. The hydrolysis is performed according to a conventional method. For example, in the case of hydrolyzing with a protease such as pepsin, the bonito section is further hydrolyzed if necessary, then adjusted to the optimal value of the enzyme, and the enzyme is added and incubated. Then, if necessary, after neutralization, the enzyme is inactivated to obtain a hydrolyzed solution. The hydrolyzed solution is filtered using a filter paper and / or celite to remove insoluble components, and the obtained filtrate is filtered using a semipermeable membrane such as cellophane or the like with a suitable solvent (for example, Tris-HCl buffer, After sufficient dialysis in a neutral buffer such as a phosphate buffer, the solution containing the components in the filtrate and having passed through the semipermeable membrane is subjected to a strongly acidic cation exchange resin (for example, Dow Chemical Co., Ltd.). Dowex 50W, etc.) to obtain a fraction containing a component having activated oxygen inhibitory activity from the adsorbed fraction, and filter the obtained activated oxygen inhibitory activity fraction by cation exchange gel filtration (for example, SP made by Pharmacia). -S
ephadex C-25), and the obtained activated oxygen inhibition active fraction is further fractionated by reverse phase HPLC.

The novel tripeptide does not induce antibody production and does not cause anaphylactic shock when repeatedly administered intravenously. Also consists array structure of the tripeptide L- amino acids only, after administration, because it is gradually degraded by proteases in vivo toxicity is extremely low safety is very high (LD _50> 5000 mg
/ Kg: oral administration to rats). Tripeptides according to the present invention, injections using additives such as commonly used excipients,
It can be prepared into tablets, capsules, granules, powders and the like. The method of administration usually includes injection into mammals (eg, humans, dogs, rats, etc.) deficient in SOD or oral administration. The dose may be, for example, 0.03 of tripeptide / kg of animal body weight.
It is an amount of 1-10 mg. The frequency of administration is usually about once to four times a day, but it can be appropriately adjusted depending on the administration route. The types of excipients, binders, disintegrants, lubricants, etc. used in the above various formulations are not particularly limited, and those used in ordinary injections, powders, granules, tablets or capsules are used. can do.

[0008] Examples of additives used in tablets, capsules, granules and powders include the following. As excipients, sugars such as crystalline cellulose, sugar alcohols such as mannitol, starch, anhydrous calcium phosphate, etc .; as binders, starches, hydroxypropylmethyl cellulose, etc .; as disintegrants, carboxymethyl cellulose and its potassium salts Lubricating agents include stearic acid and its salts, talc and waxes. In preparing the preparations, odorants such as menthol, citric acid and salts thereof, and fragrances can be used as necessary. The sterile composition for injection is prepared by dissolving the novel tripeptide of the present invention in water for injection, physiological saline and a sugar alcohol injection such as xylitol or mannitol, or a glycol such as propylene glycol or polyethylene glycol by a conventional method. It can be suspended to prepare an injection. At this time, buffers, preservatives, antioxidants and the like can be added as necessary. The preparation containing the novel tripeptide of the present invention may be in the form of a lyophilized product or a dry powder, and may be used by dissolving it with a usual dissolving agent, for example, water or physiological saline when used.

[0009] Activated oxygen is generated in phagocytes such as macrophages, and has a role of decomposing foreign substances that have been engulfed by phagocytes. However, when activated oxygen is excessively produced, it is secreted out of cells. Disturb other organizations. The novel tripeptide according to the present invention has an excellent activated oxygen inhibitory effect and exhibits an activated oxygen free radical scavenging effect and an antioxidant effect. It is effective for arthritis and rheumatism, for example, as an anti-inflammatory agent, and is also useful for Behcet's disease, myocardial infarction and the like.

[0010]

The present invention will be described in more detail with reference to the following examples, which are production examples and test examples. Production Example 1 A 7-day roasted product manufactured by the ventilation-type roasting method (Arabushi)
After finely cutting 1.16 g, 1 l of deionized water was added and homogenized. 34.8 g of morsin F (manufactured by Seishin Pharmaceutical Co., Ltd.) was added to the obtained skipjack section homogenate, adjusted to pH 3.0, and incubated at 37 ° C. for 20 hours. The morphine-decomposed solution of the bonito section homogenate thus prepared was ultrafiltered using a Diaflow membrane (YM-10 type membrane manufactured by Amicon, fractionated molecular weight 10,000). The obtained filtrate was subjected to chromatography using a column packed with Dowex 50W × 4 (H ⁺ ). Washed with deionized water, elution the eluate was concentrated performed in _2N-NH 4 OH. The concentrated solution was subjected to chromatography on a Sephadex G-25 column to fractionate a peptide fraction (fraction numbers 24-35). The column chromatograph is shown in FIG. The peptide fraction was concentrated to obtain a skipjack section-derived peptide solution (crude peptide powder). Further, this peptide solution (1.5 g as a crude peptide powder) was SP-
Chromatography on a Sephadex C-25 (H ⁺ ) column yielded SP-1 as each peptide fraction.
Fractions (fraction numbers 13-31), SP-2 fractions (fraction numbers 32-53) and SP-3 fractions (fraction numbers 54-70)
Was isolated. The column chromatograph is shown in FIG. Each of these peptide fractions is freeze-dried to obtain a purified peptide powder (hereinafter referred to as skipjack peptide) as SP.
-1 fraction 0.72 g, SP-2 fraction 0.32 g and SP
-3 fraction 0.28 g was obtained. Among the bonito node peptides fractionated in this way, SP having high activated oxygen inhibitory activity
-3 fraction of peptide powder was dissolved in deionized water (7m
g / 25 μι) and HPLC was performed. The conditions were as follows: Nomura Chemical Develosil ODS-5
(Φ4.6 mm ID × 25 cmL), and 0.05% trifluoroacetic acid (hereinafter abbreviated as TFA) to 25% acetonitrile / 0.05% TF as a mobile phase.
By the concentration gradient method in A, chromatography was performed at a flow rate of 1.0 ml / min and a detection wavelength of 220 nm to obtain a peptide fragment having a strong activated oxygen inhibitory action at an elution time of 45.733 minutes. The result is as shown in FIG. The amino acid sequence of the peptide having an inhibitory effect on activated oxygen obtained as described above was obtained from Protein Sequencer 4 manufactured by Applied Biosystems (ABI).
Determined using 77A type. As a result, it was confirmed that the peptide was a tripeptide represented by an L-form amino acid sequence represented by the following formula: Met-Lys-Met. When the skipjack section peptide according to the present invention is formulated as an activated oxygen inhibitor, for example, in a tablet, it may be treated according to a conventional method, for example, as follows: (1) 13 g of peptide, (2) 87 g of lactose,
(3) 29 g of corn starch and (4) 1 g of magnesium stearate were used as raw materials, and first (1), (2) and 17
g of cornstarch is mixed, granulated together with a paste made from 7 g of cornstarch, 5 g of cornstarch and (4) are added to the granules, and the resulting mixture is compressed with a compression tablet machine to produce 1,000 tablets. I do.

Production Example 2 This example is a production example by a synthesis method of Met-Lys-Met. The tripeptide was synthesized by a solid phase method using a peptide synthesizer model 430A manufactured by Applied Biosystems (ABI). As the solid support, a resin obtained by chloromethylating a styrene-divinylbenzene copolymer (polystyrene resin) was used. First, according to the amino acid sequence of the tripeptide, methionine on the C-terminal side was reacted with a chloromethyl resin according to a conventional method to obtain a peptide-bound resin. At this time, a t-Boc amino acid protected with a t-butoxycarbonyl (hereinafter abbreviated as t-Boc) group was used. Next, this peptide-bonded resin was suspended in a mixture of ethanediol and thioanisole, stirred at room temperature for 10 minutes, added with trifluoroacetic acid under ice cooling, and further stirred for 10 minutes. Trifluoromethanesulfonic acid was added dropwise to the mixture, and the mixture was stirred at room temperature for 30 minutes. The product was precipitated by adding anhydrous ether and separated.The precipitate was washed several times with anhydrous ether, and then dried under reduced pressure. And dried. The crude synthetic tripeptide thus obtained was dissolved in distilled water,
Purification was performed by HPLC using a reverse-phase column C ₁₈ (5 μ). Using (A) distilled water containing 0.1% TFA and (B) acetonitrile solution containing 0.1% TFA as the mobile phase, solution (A) was subjected to a concentration gradient method of 87% -68% for 20 minutes to give a flow rate of 1%. Chromatography was performed at 0.6 ml / min. The eluted fraction detected at an ultraviolet wavelength of 214 nm and showing the maximum absorption was collected and lyophilized to obtain the target synthetic tripeptide.

As a result of mass spectrometry analysis of this synthetic tripeptide, it was confirmed that it was a tripeptide represented by an L-form amino acid sequence represented by the following formula: Met-Lys-Met. The result of this mass spectrum is as shown in FIG. The tripeptide of the present invention obtained by the synthesis is confirmed to have an activated oxygen-inhibiting effect by confirming an activated oxygen free radical scavenging effect and an antioxidant effect by the following in vitro test. Was.

Test Example 1 (Measurement of scavenging action of activated oxygen free radical by chemiluminescence method) Cypridina-luciferin derivative (CLA) was composed of singlet oxygen ( ¹ O _2. ) And superoxide anion (
^- O ₂ ·) is an effective chemiluminescence reagent that specifically detects, inventors [Agric. Biol. Chem. , 5
5,157-160 (1991)] Superoxide dismutase and (SOD) and CLA by quenching experiments using the quencher by a method ^- reaction rate of the O ₂ · is calculated. CLA (C ₁₃ H ₁₁ ON ₃ , manufactured by Tokyo Chemical Industry Co., Ltd., final concentration 1.39 × 10 ^{−7 to} 4.64 × 10 ⁻⁸ ) solution 1
0 μl, albumin (50 mg / ml, Sigma Chemical Co.) 500 μl, xanthine oxidase (1.45 u)
nit / ml, manufactured by Sigma Chemical Co., Ltd.) in an order of 50 μl was put into a cylindrical quartz cell (inner diameter: 14 mm, height: 60 mm), transferred to a sample chamber of a luminometer (Aloka BLR-102B, manufactured by Hamamatsu Photonics), and 3 mM hypoxanthine was added. 200 μl of the solution was injected, and chemiluminescence was measured by single photon counting from the bottom of the cell. In the absence and, if the quencher is present ^- the ratio of O 2 _· emission intensity (I
₀ / I) is I ₀ / I = 1 + [k ₃ / (k ₁ + k ₂ [CL
A])] × [Q]. Here [Q] is activated oxygen inhibitor, _{k 1} is ^- O ₂ · quenching rate constant, _{k 2} is ^-
Reaction rate constant of O ₂ · and the [CLA], _{k 3} is ^- O ₂ ·
And [Q] show the reaction rate constant. Table 1 shows the activated oxygen inhibitory activity (quenching rate) of the purified skipjack section-derived peptide powder according to the present invention, that is, the skipjack section peptide, which exhibits an activated oxygen free radical scavenging effect.

[Table 1] The activated oxygen-inhibiting activity value (reaction rate constant k ₃ ) of the novel tripeptide according to the present invention, which indicates the activated oxygen free radical scavenging action, is 1.24 × 10 ⁻⁶ M ⁻¹ sec ⁻¹ . The activated oxygen inhibition activity value (reaction rate constant k ₃ ) of the sample SOD, which indicates the activated oxygen free radical scavenging action, is 3.47 × 10 ⁻⁸ M ⁻¹ sec ⁻¹ .

Test Example 2 (Measurement of antioxidant action) To measure the antioxidant action, the reaction solution was 51.1 mg of linoleic acid and 4.052 m of ethanol.
1, 0.05M phosphate buffer (pH 7.0) 4.0m
l to a mixed solution of 1.948 ml of deionized water, 1-3 mg of a peptide having an antioxidant effect was added to adjust the total amount to 10 ml. This solution was sealed in a test tube with a screw, left in a thermostat at 50 ° C., and the peroxide value of linoleic acid was measured every 24 hours by the iron-rodan method. That is, the reaction mixture was added.
1 ml, 9.7 ml of a 75% ethanol solution, 0.1 ml of a 30% rhodan ammonium solution, and 0.1 ml of a 3.5% hydrochloric acid solution containing 0.02 M ferric chloride were allowed to react for 3 minutes, followed by an absorbance of 500 nm. Was measured. At that time, 500
The number of days until the absorbance at nm reached 0.300 was defined as the induction period (days). FIG. 5 shows the activated oxygen inhibitory activity (induction period) of the purified skipjack section-derived peptide powder according to the present invention, ie, the skipjack section peptide, which exhibits an antioxidant effect. The activated oxygen inhibitory activity value (day of induction) showing the antioxidant effect of the novel tripeptide of the present invention is 1 m of tocopherol.
For 6.5 days of g, 0.1 mg of tripeptide 8.
It is 21 days.

[0015] Test Example 3 (Measurement of superoxide dismutase-like activity) superoxide dismutase (SOD) superoxide anion ^(- _{O 2} ·) a disproportionated into hydrogen peroxide and oxygen reaction (2 ^- O It is well known as an enzyme catalyzed by ( ₂ · + 2H ⁺ → H ₂ O ₂ + O ₂ ). The method for measuring the SOD-like activity (activated oxygen inhibitory activity) of the tripeptide according to the present invention is described by Uchida et al.
81-1186 (1998)], using a method using a tetrazolium salt XTT in which reduced formazane is water-soluble. That is, 3 ml was placed in a test tube containing 2.5 ml of 50 mM sodium carbonate buffer (pH 10.2).
mM xanthine, 3 mM EDTA, 1 mM XTT
[3 ′ (1-[(phenylamino) -carb)
onyl] -3,4-tetrazolium) -bi
s (4-methoxy-6-nitro) benze
nesulfonic acid hydrate],
And 0.1 ml of a sample solution, respectively, and immediately added 0.1 ml of 57 mU / ml xanthine oxidase (XOD) as a trigger. After reaction at 25 ° C. for exactly 20 minutes, the absorbance at 470 nm was measured. ^The concentration of the inhibitor at which the reduction of XTT by O _2. Was inhibited by 50% was determined by the IC ₅₀ value. The SOD-like activity (activated oxygen inhibition activity) of the tripeptide according to the present invention is:
IC ₅₀ value; 32 μM. Incidentally, the IC ₅₀ value of the standard reduced glutathione is 74 μM.

Test Example 4 (Measurement of activating oxygen free radical scavenging action by ESR)
A type 0 electron spin resonance device (ESR) was used. Superoxide anion by reacting xanthine and xanthine oxidase _{^{(XOD) (- O 2 ·}} ) is generated. This ^- the O ₂ · measured by ESR is combined with the spin trapping agent (DMPO). In this case the superoxide dismutase (SOD) is present ^- O ₂ · is erased, spin adduct (DMPO ^- O ₂ ·) amount decreases. Since this is proportional to the amount of SOD, SOD-like activity can be measured. ^- O ₂ · scavenging activity values are expressed in unit numbers of SOD. That is, 50 μl of 20 mM pH 7.8 hypoxanthine solution, 5.5 mM pH 7.8 DTPA (d
ieethleamineaminepentace
tic acid) solution 40 μl, sample (distilled water for control) 50 μl, stock DMPO 10 μl, 5 μl
Mix 50 μl of 0-fold diluted XOD in order and start the sweep after 1 minute with ESR. ^The O ₂ · erase activity value is determined from the calibration curve of SOD. Tripeptide according to the present invention ^- O ₂ · scavenging activity value is 264.8units / g. Incidentally, the preparation of reduced glutathione ^- O ₂ · scavenging activity value 105.4
units / g. When iron reacts with hydrogen peroxide,
OH radicals are generated. The OH radical is combined with the spin trapping agent DMPO and measured by ESR. At this time, if an OH radical scavenger is present in the sample, the spin adduct (DMPO.OH) decreases. Therefore, the amount of spin adduct at the time of control is set to 100%, and the elimination rate of OH radicals is measured. In addition, the measurement is 10 mg of the sample.
/ Ml, and diluted to 1 mg / ml, and the erasure rate is determined. That is, a solution 75 containing a mixture of 1 mM ferrous sulfate and EDTA.
μl, sample (distilled water for control) 50 μl,
50 μl of 0.1 M DMPO, 75 mM of 10 mM hydrogen peroxide
Mix μl sequentially and start sweeping with ESR after 30 minutes. The intensity of the peak at the time of control is defined as 100%, and the erasure rate is determined from the decrease of the peak at the time of sample addition. The OH radical scavenging rate of the tripeptide according to the present invention is 73.2%.
(10 mg / ml) and 45.6% (1 mg / ml). The OH radical scavenging rate of the standard reduced glutathione was 41.5% (10 mg / ml), 31.2% (1 mg / ml).
/ Ml). As a result of the above test, the novel tripeptide according to the present invention has an activating oxygen free radical scavenging action and an antioxidant action.
(In test tube) It was confirmed in the test that a significant activated oxygen inhibiting effect was exhibited. Therefore, the tripeptide according to the present invention is an ischemic heart disease subject to be an activated oxygen inhibitor,
It is useful as a therapeutic or prophylactic agent for patients with rheumatoid arthritis and severe burns. Incidentally, the tripeptide according to the present invention,
In a peptide structurally represented by its amino acid sequence, it can also be employed in the structure.

[0017]

[Brief description of the drawings]

FIG. 1 is a diagram showing the results of separation and purification of a peptide having an activated oxygen inhibitory effect by Sephadex G-25 column chromatography in Production Example 1 of a morphosin lysate of skipjack section according to the present invention. In the figure, insulin having a molecular weight of 6,000 and molecular weight of 3,500 are used as markers.
Insulin B chain, Insulin A chain having a molecular weight of 2,550, bacitracin having a molecular weight of 1,450 and a molecular weight of 75
Of glycine was used.

FIG. 2 is a diagram showing the results of separation and purification of a peptide having an activated oxygen inhibitory effect by SP-Sephadex C-25 (H +) column chromatography in Production Example 1 of the skipjack section peptide according to the present invention.

FIG. 3 is a view showing the results of separation and purification of a fragment of a tripeptide having an activated oxygen inhibitory effect by reverse-phase HPLC in Production Example 1 of the skipjack section peptide according to the present invention.

FIG. 4 is a view showing a mass spectrum of the synthetic tripeptide obtained in Production Example 2 of the tripeptide according to the present invention.

FIG. 5 is a graph showing the induction period (days) of the SP fraction (1, 2, 3 mg) of the skipjack section peptide according to the present invention in Production Example 1, showing the antioxidant effect and the activated oxygen inhibitory effect. It is.

Continuation of the front page (51) Int.Cl. ⁷ identification code FI A61P 37/00 A61K 37/02 (58) Field surveyed (Int.Cl. ⁷ , DB name) C07K 5/08 A61K 38/00 A61K 31 / 00 C12N 9/99 BIOSIS (DIALOG) CA (STN) WPI (DIALOG)

Claims (2)

(57) [Claims] 1. A novel tripeptide represented by an L-form amino acid sequence represented by the following formula: Met-Lys-Met. 2. An activated oxygen inhibitor comprising, as an active ingredient, a novel tripeptide represented by an L-form amino acid sequence represented by the following formula: Met-Lys-Met.