JPH05331063A - Antagonist for endothelin receptor - Google Patents

Abstract

PURPOSE:To obtain an antagonist having endothelin receptor antagonistic action and useful for the treatment of hypertension, acute renal insufficiency, etc., by using non-peptide pheophorbide derivative as an active component. CONSTITUTION:The antagonist contains a derivative of formula [R1 is CH3 or CHO; R2 is H or (esterified) carboxyl] as an active component. The antagonist administered by oral administration (e.g. in the form of tablet, pellet, etc., at a rate of 0.1-100mg/kg/day) or parenteral administration (e.g. in the form of injection at a rate of 0.01-20mg/kg/day). The compound of formula can be produced by extracting a photosynthetic organism with an organic solvent such as methanol or ethyl acetate and purifying the extract by chromatography, etc. The compound of formula is preferably pheophorbide a (R1 is CH3 and R2 is carboxymethyl), etc.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an endothelin receptor antagonist containing a pheophorbide derivative as an active ingredient.

[0002]

2. Description of the Related Art Has a strong vasoconstrictor action and pressor action,
Compounds that inhibit receptor binding to endothelin, which is considered to be a causative agent of hypertension, acute renal failure, myocardial infarction, and vasospasm, antagonize the physiological activity of these endothelins and are useful as pharmaceuticals. .. So far
Various peptides having an endothelin receptor antagonistic activity have been reported, but anthraquinone derivatives have only been reported as a non-peptidic compound (Japanese Patent Laid-Open No. HEI 3).
-47163). On the other hand, pheophorbide derivatives and metal complexes of pheophorbide derivatives are known as cancer therapeutic agents (JP-A-61-2279, JP-A-61-83).
185). However, nothing is disclosed about the endothelin receptor antagonism of the pheophorbide derivative.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides an endothelin receptor antagonist containing a non-peptide pheophorbide derivative as an active ingredient.

[0004]

As a result of intensive studies in view of the above circumstances, the present inventors have found that a pheophorbide derivative has an excellent endothelin receptor antagonistic action, and completed the present invention. That is, the present invention provides formula (I):

[Chemical 2] [In the formula, R ₁ represents CH ₃ or CHO, and R ₂ represents hydrogen or an optionally esterified carboxyl group] and an endothelin receptor antagonist containing a pheophorbide derivative represented by the formula as an active ingredient. Is. As the substituent of the optionally esterified carboxyl group, lower alkyl having 1 to 4 carbon atoms is preferable, and methyl and ethyl are more preferable.

Pheophorbide derivatives represented by the formula (I) include pheophorbide a (R ₁ is CH ₃ , R
₂ is carboxymethyl), pheophorbide b
(R ₁ is CHO, R ₂ is carboxymethyl), pyropheophorbide a (R ₁ is CH ₃ and R ₂ is hydrogen), and the like, preferably pheophorbide a and pyropheophorbide. a is mentioned.

The pheophorbide derivative is a porphyrin-related compound, and a photosynthetic organism is extracted with an organic solvent such as acetone, methanol, ethanol, chloroform or ethyl acetate to obtain a known method (JP-A-58-698).
According to 84), it can be obtained by separation and purification by a purification method such as chromatography. Known methods (Synthe
sis, 539 (1980)), chlorophyll is hydrolyzed with hydrochloric acid or the like, or an enzyme such as chlorophyllase is used to hydrolyze the phytoyl ester of chlorophyll.

In the present invention, the pheophorbide derivative includes its salt. Examples of the salt include salts with inorganic bases, salts with organic bases, salts with inorganic acids, salts with organic acids, salts with basic or acidic amino acids, and the like. The present invention relates to an endothelin receptor antagonist containing a pheophorbide derivative and a salt thereof as an active ingredient, and in mammals (eg, human, mouse, rat, cat, dog, rabbit, etc.), various diseases caused by endothelin, For example, treatment and prevention of hypertension, angina, cardiomyopathy, arteriosclerosis, myocardial infarction, Raynaud's disease, cerebral artery spasm, cerebral ischemia, aortic spasm after subarachnoid hemorrhage, asthma, acute renal failure, etc. In addition, it can be used as a vasodilator.

The endothelin receptor antagonist of the present invention can be administered orally or parenterally. Dosage forms include tablets, pellets, capsules, granules, emulsifiers, suspensions, injections and the like. These dosage forms are produced according to a conventional method using appropriate carriers, excipients, and other additives as necessary. The pheophorbide derivative represented by the formula (I) has low toxicity and can be safely used. The daily dose varies depending on the condition and weight of the patient, the type of the derivative, the administration route, and the like. Parenterally, it is subcutaneously, intravenously, intramuscularly, or intrarectally administered at about 0.01 to 20 mg / kg / day, preferably about 0.1 to 10 mg / kg / day. As an oral preparation, it is desirable to administer about 0.1 to 100 mg / kg / day, preferably about 1 to 10 mg / kg / day.

The biological activity of the pheophorbide derivative represented by the formula (I) will be described below. Test Example Endothelin Receptor Binding Inhibitory Action (1) Preparation of Porcine Ventricular Fascia Fraction After washing the aorta, atrium, and fat-free ventricle of the porcine heart, it was shredded and 10 times volume of C solution [20 mM NaHCO 3]
₃ , 0.1 mM PMSF (Phenylmethylsulfonylfluorid)
e) 1 mM EDTA (Ethylenediaminetetraacetati
acid)] and homogenize with a Polytron homogenizer. After filtering through gauze, 1500 g 15
Centrifuge for minutes, and add the supernatant (500 ml) to 40,000
Centrifuge at g for 20 minutes. Precipitate the TPE buffer (50m
M Tris buffer, pH 7.4), 0.1 mM PMS
F, 1 mM EDTA) was washed twice, and the crude receptor membrane fraction was stored at −80 ° C., and suspended in TPE buffer as needed before use. (2) ¹²⁵ I-endothelin binding test ¹²⁵ I-endothelin-1 (8
1.4 TBq / mmol, DuPont, USA) 37
0Bq was added, and a crude membrane fraction (1.4 μg protein amount) and a sample were added. The amount of non-specific binding was measured by adding 1 × 10 ⁻⁷ M endothelin-1. The reaction is 0.2 ml T
It was carried out at 37 ° C. for 90 minutes in PE buffer. After the reaction, using a cell harvester (290PHD, manufactured by Cambridge Technology, USA), a glass filter (GF
/ B, Whatman, USA) to stop the reaction by rapid filtration to stop the reaction with 10 mM Na, K-phosphate buffer (pH 7.
After washing 3 times with 4), the radioactivity remaining on the filter was measured with a gamma counter.

As a result, endothelin-1 binding was reduced to 50%.
The inhibitory concentrations (IC ₅₀ ) were 1.2 μg / ml and 1.6 μg / ml for pheophorbide a and pyropheophorbide a, respectively. Regarding pheophorbide b, the concentration at which endothelin-1 binding was inhibited by 30% (IC ₃₀ ) was about 10 μg / ml.

[0011]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Formulation example Pheophorbide a 590 mg in 10 ml of 0.1N sodium hydroxide solution prepared using the Japanese Pharmacopoeia distilled water for injection
Was dissolved and adjusted to pH 7.4 with a 0.02N hydrochloric acid solution, and then distilled water for injection by the Japanese Pharmacopoeia was added to make 100 ml. 1 ml of this solution was taken, and an injection ampoule was manufactured according to the general rules of the Japanese Pharmacopoeia formulation.

[0012]

INDUSTRIAL APPLICABILITY The present invention can provide an endothelin receptor antagonist containing a pheophorbide derivative or a salt thereof as an active ingredient. The receptor antagonist can be used as a therapeutic and prophylactic agent for hypertension, acute renal failure, cardiomyopathy, myocardial infarction, vasospasm and the like.

Claims (3)

[Claims] 1. Formula (I): An endothelin receptor antagonist comprising a pheophorbide derivative represented by the formula: wherein R ₁ represents CH ₃ or CHO, and R ₂ represents hydrogen or an optionally esterified carboxyl group. 2. The endothelin receptor antagonist according to claim 1, which is a pheophorbide derivative in which R ₁ is CH ₃ and R ₂ is carboxymethyl. 3. The endothelin receptor antagonist according to claim 1, which is a pheophorbide derivative in which R ₁ is CH ₃ and R ₂ is hydrogen.