Synthesis and antidepressant activity of substituted (omega-aminoalkoxy)benzene derivatives.

A series of substituted (omega-aminoalkoxy)benzene derivatives has been synthesized and screened for potential antidepressant activities. The effect of structural variation of these molecules has been systematically examined. Antidepressant activity was clearly displayed by 2-benzyl-1-[4-(methylamino)butoxy]benzene (7), 2-(2-hydroxybenzyl)-1-[4-(methylamino)butoxy]benzene (19), 1-[4-(methylamino)butoxy]-2-phenoxybenzene (29), and 1-[4-(methylamino)butoxy]-2-(phenylthio)benzene (31) in further pharmacological studies. These compounds did not possess the anticholinergic, antihistaminic, and muscle-relaxant side effects common to tricyclic antidepressants.

Synthesis and antianxiety activity of (omega-piperazinylalkoxy)indan derivatives.

A series of (omega-piperazinylalkoxy)indan derivatives has been synthesized and screened for potential antianxiety activities. The effect of structural modification of these molecules on activities has been systemically examined. Antianxiety activity was displayed by 5-[3-(4-phenyl-1-piperazinyl)propoxy]indan (2), 5-[3-[4-(4-fluorophenyl)-1-piperazinyl]-propoxy]indan (8), 6-fluoro-5-[3-(4-phenyl-1-piperazinyl)propoxy]indan (33), and 6-methyl-5-[3-(4-phenyl-1-piperazinyl)propoxy]indan (42), as determined in antifighting and anti-morphine tests. These derivatives in antianxiety tests were equipotent or more potent than chlordiazepoxide with less muscle-relaxant effect. They also showed weak neuroleptic-like action.

Substituted (omega-aminoalkoxy) stilbene derivatives as a new class of anticonvulsants.

A series of substituted (omega- aminoalkoxy )stilbene derivatives has been synthesized and screened for anticonvulsant activity. The effect of structural modification of these molecules on the activities has been systematically examined. Potent anticonvulsant activity was displayed by 2-[4-(4-methyl-1 piperazinyl)butoxy]stilbene (20) and some 2-[4-(3-alkoxy-1-piperidino)butoxy]stilbene derivatives (21, 37, 38, and 40), as determined by maximal electroshock seizure (MES) and pentylenetetrazol-induced convulsion tests in mice. Compound 21 exhibited more potent anti-MES activity than diphenylhydantoin and carbamazepine in further pharmacological tests in rats, and its therapeutic index was superior to those of two antiepileptic drugs.

Thrombin inhibitors. 3. Carboxyl-containing amide derivatives of N alpha-substituted L-arginine.

A series of N alpha-(arylsulfonyl)-L-arginine amide derivatives having carboxamide N-substituents with a carboxyl group was prepared and tested as inhibitors of the clotting activity of thrombin. The most inhibitory compounds were obtained when a carboxyl group was introduced into the carbon next to the amide nitrogen of N alpha-(arylsulfonyl)-L-arginine amide derivatives, e.g., N alpha-(arylsulfonyl)-L-arginyl-N-butyl-, N-(methoxyethyl)- or N-(tetrahydrofurfuryl)glycine and 4-alkyl-1-[N alpha-(arylsulfonyl)-L-arginyl]-2-piperidinecarboxylic acid, with an I50 of 1-3 X 10(-7) M.

Thrombin inhibitors. 1. Ester derivatives of N alpha-(arylsulfonyl)-L-arginine.

A series of N alpha-(arylsulfonyl)-L-arginine esters was prepared and tested as inhibitors of the clotting activity of thrombin. N alpha-Dansyl-L-arginine methyl ester was the most inhibitory of the N alpha-(arylsulfonyl)-L-arginine methyl esters. The most potent inhibitors were the n-propyl and n-butyl esters of N alpha-dansyl-L-arginine with an I50 of 2 X 10(-6) M. Esters of unsaturated straight-chain alcohols with a chain length of four carbons were also as inhibitory as the n-butyl ester. The inhibitors were hydrolyzed by thrombin and trypsin more slowly than N alpha-tosyl-L-arginine methyl ester.

Thrombin inhibitors. 2. Amide derivatives of N alpha-substituted L-arginine.

A series of N alpha-(arylsulfonyl)-L-arginine amide derivatives with substituted or unsubstituted naphthalene and heterocyclic compounds as the N alpha-substituent was prepared and tested as inhibitors of the clotting activity of thrombin. N-n-Butyl and N-n-butyl-N-methyl derivatives of N alpha-dansyl-L-arginine amide were the most inhibitory of N-alkyl and N,N-dialkyl derivatives of N alpha-dansyl-L-arginine amide. Their inhibitory effect was as potent as that of N alpha-dansyl-L-arginine-n-butyl ester with an I50 of 2 X 10(-6) M. N alpha-Substituted naphtalenesulfonyl-L-arginine amide derivatives of 4-methyl- and 4-ethylpiperidine also showed a potent inhibition with an I50 of 10(-7) to 10(-6) M. The most potent inhibitior in this study was 1-[N alpha-(4,6-dimethoxynaphthalene-2-sulfonyl)-arginyl]-4-methylpiperidine, with an I50 of 7.5 X 10(-8) M. Arginine amide derivatives of 4-methyl- or 4-ethylpiperidine with tetralin or an oxygen-containing heterocyclic compound as a N alpha-substituent showed an inhibition with an I50 less than 10(-5) M. N-Monosubstituted derivatives of N alpha-dansyl-L-arginine amide were not hydrolyzed at all by thrombin and were hydrolyzed very slowly by trypsin, and N,N-disubstituted derivatives were not hydrolyzed at all by both enzymes.

Syntheses and platelet aggregation inhibitory and antithrombotic properties of [2-[(omega-aminoalkoxy)phenyl]ethyl]benzenes.

A series of [2-[(omega-aminoalkoxy)phenyl]ethyl]benzene derivatives were synthesized and evaluated for their ability to inhibit collagen-induced platelet aggregation in vitro and to protect experimental thrombosis in mice. The results showed that the compounds were in vitro inhibitors of collagen-induced platelet aggregation. Most of them were also effective in the mouse antithrombotic assay. The compounds were found to be potent antagonists to S2 serotonergic receptor, and good correlation (r = 0.85) between their S2 serotonergic receptor antagonism and their potency as platelet antiaggregatory drugs was observed. Among the compounds studied, mono[2-(dimethylamino)-1-[[2-[2-(3- methoxyphenyl)ethyl]phenoxy]methyl]ethyl] succinate hydrochloride (12b, MCI-9042) was selected for further pharmacological and toxicological evaluation.

Effect of a synthetic thrombin inhibitor MCI-9038 on experimental models of disseminated intravascular coagulation in rabbits.

We examined the effect of a synthetic thrombin inhibitor, MCI-9038, on two experimental animal models of disseminated intravascular coagulation (DIC). In a model that DIC induced by the intravenous infusion of thrombin, MCI-9038 suppressed the decrease of platelet count by about 50% at a dose of 0.2 micrograms/kg/min and almost completely at 2 micrograms/kg/min. When MCI-9038 was administered orally, the suppressive effect was also observed. Heparin suppressed the platelet count decrease by about 50% at 1 unit/kg/min. In another model of DIC induced by lactic acid and tissue thromboplastin infusion, MCI-9038 prevented the decrease of platelet count and the consumption of coagulation factors. The suppression effect by about 50% on these changes was observed at a dose of 3.16 micrograms/kg/min. Thromboelastogram pattern indicating the consumption coagulopathy in control experiments was normalized by the MCI-9038 administration. Heparin suppressed the decrease of fibrinogen content as effectively as MCI-9038, but it was less effective on the platelet count decrease. From these results, it was concluded that MCI-9038 might be useful for the treatment of DIC.

Kinetic studies on the selectivity of a synthetic thrombin-inhibitor using synthetic peptide substrates.

The synthetic thrombin-inhibitor termed No. 205 (N-alpha-dansyl-L-arginine-4-ethyl-piperidine amide) found in our laboratories was studied kinetically using synthetic peptide substrates. The following results were obtained. 1. No. 205 inhibited thrombin competively with bz-Phe-Val-Arg-pNA and the Ki value obtained was extremely small, 3.7 x 10(-8) M. 2. No. 205 also inhibited trypsin competitively with bz-Phe-Val-Arg-pNA but the Ki value obtained was far larger than that for thrombin, 1.0 x 10(-5) M. 3. No. 205 inhibited F. Xa, plasmin and urokinase only to a small extent when estimated using 2 x 10(-4) M D-Val-Leu-Lys-pNA, bz-Ile-Glu-Gly-Arg-pNA and Glu-Gly-Arg-pNA, respectively. 4. No 205 differed from APPA in its specific inhibitory spectrum for thrombin as compared to trypsin, plasmin and F. Xa. The above results indicate that No. 205 is an extremely potent and highly selective reversible thrombin-inhibitor.

MCI-9042, a new antiplatelet agent is a selective S2-serotonergic receptor antagonist.

MCI-9042, (+/-)-1-[2-[2-(3-methoxyphenyl)ethyl]phenoxy]-3- (dimethylamino)-2-propyl hydrogen succinate hydrochloride inhibited platelet aggregation induced by collagen and secondary aggregation by ADP or epinephrine at 10(-6) M level in platelets of various species. The antiplatelet effect of MCI-9042 was potentiated in aggregation induced by a combination of serotonin with collagen. IC50 value of human platelet aggregation by the serotonin plus collagen was 1.0 x 10(-7) M. MCI-9042 inhibited serotonin release accompanied with collagen-induced platelet aggregation, while it did not affect serotonin uptake into platelet. MCI-9042 also potently inhibited the S2-serotonergic receptor-mediated contraction of rat caudal artery by serotonin in a competitive manner with a Ki value of 1.79 x 10(-8) M, while S1 receptor- or adrenergic receptor-mediated vasoconstriction was inhibited more weakly. Platelet adhesiveness, c-AMP level in platelets and the conversion of arachidonic acid to thromboxane A2 were not influenced by MCI-9042. These results suggest that MCI-9042 is a selective S2-serotonergic receptor antagonist, exhibiting the inhibition of S2-serotonergic potentiated platelet aggregation and the suppression of blood vessel constriction mediated by S2-serotonergic receptor.

Effect of a selective thrombin inhibitor MCI-9038 on fibrinolysis in vitro and in vivo.

The effect of a selective thrombin inhibitor, (2R, 4R)-4-methyl-1-[N2-[(3-methyl-1,2,3,4-tetrahydro-8-quinolinyl)sulfonyl]- L-arginyl]-2-piperidinecarboxylic acid (MCI-9038), on the fibrinolysis induced by t-PA and u-PA was studied in vitro and in vivo. MCI-9038 remarkably reduced the lysis time of the plasma clot generated by the addition of calcium chloride to the plasma at the concentration ranging from 0.01 to 0.3 microM. Heparin also reduced the plasma clot lysis time with a lower effect than MCI-9038. The fibrin crosslinkage in the plasma clot was inhibited by MCI-9038 or heparin. MCI-9038 potently inhibited the factor XIIIa generation from factor XIII by thrombin. The effect on the in vivo thrombolysis was studied on the arterial thrombosis generated by the endothelial cell injury of the rabbit carotid artery by acetic acid. t-PA dissolved the thrombi with the infusion at 0.96 mg/kg over 2 h without a significant activation of a systemic fibrinolysis. u-PA dissolved the thrombi with the infusion at 180,000 and 360,000 IU/kg over 2 h. At a dose of 0.48 mg/kg t-PA or 90,000 IU/kg u-PA, the thrombi were not dissolved, but the combined use of MCI-9038 at 1.2 mg/kg over 2 h effectively dissolved the thrombi. Thus, combination of MCI-9038 with plasminogen activators accelerated thrombolysis of an experimental thrombosis in rabbits.

Similarity and dissimilarity in the stereogeometry of the active sites of thrombin, trypsin, plasmin and glandular kallikrein.

The relationship between chemical modifications of arginine derivatives and inhibitory activity to trypsin, plasmin and glandular kallikrein was investigated comparing with that of thrombin and concluded as follows: The hydrophobic binding pocket, which has been reported previously to be stereogeometrically very similar in trypsin and thrombin, corresponded to the length of ethylpiperidine. Concerning the site (termed the P site) next to the hydrophobic binding pocket, there were large differences in stereogeometry between trypsin and thrombin; the binding site of trypsin extended further to allow propyl and phenyl group attached to piperidine, while that of thrombin would be much narrower and unable to allow them. The P sites of plasmin and glandular kallikrein resembled that of trypsin in being able to allow phenyl group. To substantialize the hydrophobic binding pocket and the P site, a (2R, 4R)-MQPA-trypsin complex model was generated using the results of X-ray crystallography of (2R, 4R)-MQPA and BPTI-trypsin complex by calculation to minimize van der Waals contacts, and it was of great use for understanding the geometry of the active sites of trypsin, thrombin, plasmin and glandular kallikrein.