Synthesis of N-substituted 4,6-dioxo-imidazo[3,4-c] thiazoles and their analgesic activity in mice

A new series of N-substituted dioxo-imidazo[3,4-c]thiazoles have been prepared and evaluated for their analgesic activity. The structures of these new derivatives were confirmed by lR, 1H NMR and 13C NMR spectra, and by elemental analysis. When administered intraperitoneally to mice all derivatives were devoid of any toxic effect, even at the high dose of 800 mg kg(-1). In the phenylbenzoquinone-induced abdominal constriction test in mice, eight of the nine synthesized compounds exhibited significant antinociceptive properties with ED50 values (50% effective dose) ranging from 46.7 to 104.7 mg kg(-1) intraperitoneally. Further investigation demonstrated that analgesic activity of the most effective derivatives 5e and 5f partly involved opioidergic and/or noradrenergic pathways.

[Synthesis and antidepressive activity study of aryl and heteroaryl carboxamides of benzylpiperazine]

The synthesis of 44 original amide derivatives of benzylpiperazine and some analogues of befuraline and piberaline is reported. All compounds have been tested as antidepressive agents. According to the tests, amides 1, 24 and mainly 31 (dihydrobefuraline) seem to provide elevated antidepressive activity.

Antioxidant properties of novel lipophilic ascorbic acid analogues

Structural modifications of ascorbic acid by the introduction of lipophilic moieties has led to derivatives with increased stability against thermal and oxidative degradation. Two series of new lipophilic ascorbic analogues were synthesized to obtain antioxidants devoid of autooxidant properties: 4-benzoyl-3-hydroxyfuran-2(5H)-ones (3a-j) and 4-acetyl-5-aryl-3,4-dihydrofuran-2(5H)ones (5a-f). These compounds were submitted to three different tests: reduction of the stable free radical, 1,1-diphenyl-2-picrylhydrazyl (DPPH); superoxide-anion scavenging assay; and lipid-peroxidation assay. Most compounds interacted with DPPH: at a concentration of 5 x 10(-3) M, the reducing activity of 4-benzoyl derivatives, 3c and 3h, was more than 50%; under the same conditions, the rate of inhibition for 4-acetylbutanolides, 5a and 5f, reached 60.6% and 87.3%, respectively; 93.3% inhibition was observed with ascorbic acid. In the superoxide-anion scavenging assay, at a concentration of 1 mg mL(-1), 4-benzoyl derivatives, 3g and 3i, exhibited a good activity, with IC50 (dose resulting in 50% inhibition) values of 1.45 and 1.35 x 10(-3) M, respectively. 4-Acetylbutanolide, 5f, significantly inhibited the Fe2+/ADP/ascorbate-induced lipid peroxidation of rat liver microsomes with an IC50 of 4.9 x 10(-4) M. This study demonstrates that enol functions in the structure of ascorbic acid analogues are not absolutely essential to bring about antioxidant effects.

Synthesis and analgesic effects of 5-[4-(arylpiperazin-1-yl)alkylamino]-4-benzyl-3-methyl-1,2-oxa zin-6-one s

A series of 5-[4-(arylpiperazin-1-yl)alkylamino]-4-benzyl-3-methyl-1,2-oxaz in-6-ones was synthesized and evaluated for analgesic activity. The structures of these new oxazine derivatives were confirmed by IR, 1H-NMR spectra and by elemental analysis. The three most active compounds, 3c, 3e and 3g possessed significant antinociceptive effects in the phenylbenzoquinone-induced wrigthing test (PBQ-test) in mice, with ED50 values ranging from 19.7 to 68.0 mg/kg i.p. In addition these compounds presented a low toxicity (LD50 > 800 mg/kg i.p.) and did not significantly reduce the spontaneous locomotor activity of mice. They interacted in a synergistic manner with morphine but nevertheless each compound presented its own profile. Thus the analgesic activity of 3c and 3e was naloxone sensitive, suggesting in mu opioidergic mechanism. Otherwise 3c and 3d analgesia was attenuated by oral administration of yohimbine and therefore seemed to be mediated via noradrenergic pathway. Finally, 5-hydroxytryptophan associated to carbidopa only potentiated 3e analgesia, demonstrating an involvement of a serotoninergic mechanism.

Spirobutenolides substituted by arylpiperazinyl-carbonyl moieties. Synthesis and antinociceptive properties

The synthesis and spectral data of some new cyclohexane-2-spiro-[2,5-dihydro-3-(N-arylpiperazin-1-yl-carbonyl) -4-methyl- 5-oxo]furanes are reported. These compounds were subjected to pharmacological tests for evaluation of antinociceptive effects and interactions with opioidergic and monoaminergic systems. With respective ED50 values of 116.4 and 87.0 mg/kg i.p., derivatives 2b and 2e were the most active spirobutenolides in the phenylbenzoquinone-induced writhing test (PBQ-test) without neurotoxic effects. They potentiated morphine analgesia and were also active at the dose of 150 mg/kg i.p. in the hot plate test while they exhibited sedative effects from the dose of 100 mg/kg i.p. In addition, 2b and 2e analgesia was antagonized by naloxone, then again potentiated by 5-hydroxytryptophan associated to carbidopa in the PBQ-test, demonstrating involvement of opioidergic and serotonergic pathways in the analgesic properties of both compounds. Furthermore, antinociceptive effects of 2e were attenuated by oral administration of yohimbine suggesting that its analgesic activity was also partly related to a noradrenergic mechanism.

Synthesis and anticonvulsant properties of triazolo- and imidazopyridazinyl carboxamides and carboxylic acids

Analogues of 3-amino-7-(2,6-dichlorobenzyl)-6-methyltriazolo[4,3-b]pyridazine PC25 containing amide or carboxylic acid function were synthesized and tested for anticonvulsant activity. The compounds having the imidazole ring substituted with an amide group have been found to be generally more active against maximal electroshock-induced seizures in mice (15.2 < or = ED50 < or = 37.5 mg kg(-1) orally). Furthermore, maximum activity was generally associated with a 2,6-dichlorobenzyl substitution pattern. 3-Amido-7-(2,6-dichlorobenzyl)-6-methyltriazolo[4,3-b]pyridazine 4b was also protective in the pentylenetetrazole-induced seizures test (ED50 = 91.1 mg kg(-1) orally) and blocked strychnine-induced tonic extensor seizures (ED50 = 62.9 mg kg(-1) orally). Moreover, calculated electrostatic isopotential maps of the whole active compounds were quite similar and, consequently, could be associated to optimum anticonvulsant activity.

Synthesis of thiazolotriazine derivatives and their antinociceptive effects in mice

Ans raci A series of 2-(4-arylpiperazin-1-yl-methyl)-4-methyl-1-oxo-5,6,8,8a-tetrahydro -thiazolo[3,4-d] [1,2,4]triazines was prepared and tested for antinociceptive activity. The compounds were prepared by the Mannich reaction from the corresponding 2-unsubstituted thiazolotriazines. When administered intraperitoneally most were found to have potent analgesic activity in the mouse during tests of phenylbenzoquinone-induced abdominal constriction; ED50 values (doses resulting in half the maximum effect) ranged from 10 to 87 mg kg(-1). Derivatives with a 3-chloro- or 4-fluorophenylpiperazinylmethyl side-chain in the 2-position of the bicyclic system were, when administered intraperitoneally at doses greater than 25 mg kg(-1), also effective in the hot-plate test without associated sedative effects. The compounds have a large therapeutic index; intraperitoneal LD50 values (doses which result in the death of half the animals) were > 700 mg kg(-1). Naloxone attenuated the analgesic activity of the 3-chloro derivative, suggesting the participation of micro-receptors in the antinociceptive effects of this drug. In addition, a nonopioid mechanism, probably related to enhancement of the release of 5-hydroxytryptamine and noradrenaline, or inhibition of the neuronal re-uptake of these compounds, has been evinced to explain the analgesic properties of the 3-chloro or 4-fluoro derivatives. These results provide evidence for the involvement of noradrenergic and 5-hydroxytryptaminergic pathways in the analgesic activity of 3 and 4. Because of their potential effectiveness, the 3-chloro- or 4-fluorophenylpiperazinylmethyl derivatives might be suitable for treatment of a wide variety of painful conditions and could be attractive reserve agents for patients dissatisfied with opioids.

Antioxidant activity of some ascorbic and cinnamic acids derivatives

Some 4-benzoyl 3-hydroxy furan-2 (5H) ones (3a-d) and 2-amino 3-hydroxymethyl 4-aryl 4-oxo 2-butenoic acids (4a-h) have been synthesized. Compound 3c with an isobutyl substituent in the 5-position of the furan ring was the most effective (IC50 = 8.69 x 10(-4) M) in scavenging the superoxide anion. In vivo, 3c was also protective against reperfusion injury.

Effects of two N-arylpiperazinylmethylpyrazolo [1,5-d][1,2,4]triazine derivatives in pain and antidepressant tests in mice

The antinociceptive and antidepressant effects of two pyrazolotriazine derivatives, 2-phenyl-3,3a-dihydro-4-oxo-5-(4-phenylpiperazin-1-yl) methyl-pyrazolo[1,5-d][1,2,4]-triazine (SM1) and 2-phenyl-3,3a-dihydro-4-oxo-5-[4-(4-fluorophenyl)piperazin-1-yl] methylpyrazolo[1,5-d][1,2,4] triazine (SM3) have been investigated in mice using classical pharmacological tests. The intraperitoneal LD50 values of SM1 and SM3 were 253.4 and 218.8 mg kg-1 respectively. SM1 and SM3 showed analgesic properties in the phenylbenzoquinone-induced abdominal constriction test (ED50 approximately 10-15 mg kg-1, i.p.) and in the hot-plate test. The antinociceptive effects of the triazines were significantly reduced by administration of naloxone (1 and 3.2 mg kg-1, s.c.) and yohimbine (1 mg kg-1, p.o.). Acute intraperitoneal administration of both compounds (1 mg kg-1 SM1 or 1.5 mg kg-1 SM3) potentiated morphine (0.15 mg kg-1, s.c.) analgesia in the phenylbenzoquinone test. Although this synergistic activity was not reversed by methysergide (0.5 mg kg-1, i.p.), the analgesic activity of both compounds was enhanced by administration of 5-hydroxytryptophan (50 mg kg-1, i.p.) in conjunction with carbidopa (25 mg kg-1, i.p.). Furthermore, neither compound (at 100 mg kg-1, i.p.) significantly reduced the duration of immobility of mice in the forced swimming test, and both (at 75 mg kg-1, i.p.) were ineffective at enhancing the toxic effects of yohimbine (30 mg kg-1, s.c.). Only SM3 (ED50 = 74.5 mg kg-1, i.p.) significantly antagonized reserpine (2.5 mg kg-1, i.p.)-induced ptosis. Thus, the results suggest that SM1 and SM3 have antinociceptive properties related to co-involvement of opioidergic and alpha 2-adrenoceptor mechanism without associated antidepressant properties.

Synthesis and analgesic effects of 3-substituted 4,6-diarylpyridazine derivatives of the arylpiperazine class

A new series of 4,6-diaryl pyridazines substituted in the 3-position by arylpiperazinyl moieties was synthesized and evaluated for analgesic activity. Five out of the nine tested compounds possessed significant antinociceptive effects in the phenylbenzoquinone-induced writhing test (PBQ test) with ED50 values ranging from 26.0 to 37.7 mg/kg ip. The most active derivatives 2a, 2d and 2h had a low toxicity (LD50 > 800 mg/kg ip) but showed some sedative and neurotoxic effects from the dose of 50 mg/kg ip. The three selected pyridazines were devoid of activity in the hot-plate test. However, analgesic activity of 2d and 2h was significantly reversed by naloxone in the PBQ test. Administered at the low dose of 5 mg/kg ip, 2h greatly potentiated the antinociceptive response induced by morphine (0.15 mg/kg sc). In addition, analgesic effects of 2h (2.5 mg/kg ip) were also potentiated by 5-hydroxytryptophan combined with carbidopa. These results suggest that pyridazine 2h induces analgesia, which is mediated via both opioid and serotonergic mechanisms.

Synthesis and pharmacological evaluation in mice of new non-classical antinociceptive agents, 5-(4-arylpiperazin-1-yl)-4-benzyl-1,2-oxazin-6-ones

Several 5-(4-arylpiperazin-1-yl)-4-benzyl-1,2-oxazin-6-ones have been synthesized and tested for analgesic activity in a visceral pain model (phenylbenzoquinone-induced writhing test = PBQ test). A good correlation has been found between the antinociceptive effects of drugs and both their lipophilic and steric properties. The most active derivatives 5c and 5f, with intraperitoneal ED50 values of 10.5 and 10.3 mg kg-1 respectively, were more extensively investigated by evaluating their analgesic activity in a somatosensory pain model (hot plate test), as well as their sedative properties. Furthermore, naloxone suppressed the effect of 5c and 5f in the PBQ test, though these derivatives were ineffective to potentiate morphine analgesia. Pretreatment with yohimbine did not significantly attenuate the analgesic effects of 5c and 5f. In addition, pretreatment with 5-hydroxytryptophan associated with carbidopa also failed to potentiate the antinociceptive effects of 5c and 5f. So, a part of the analgesic activity of 5c and 5f seems to be related to an opioidergic mechanisms, especially at the mu receptor level. Molecular modeling studies performed on the opiate drug morphine and on the most stable conformer of 5f showed structural similarities between these two molecules.

Synthesis of peripherally acting analgesic 3-arylpiperazinyl-5-benzyl-pyridazines

A series of 3-arylpiperazinyl-5-benzyl-pyridazines was synthesized and evaluated for analgesic activity. The structures of these new pyridazine derivatives were confirmed by IR, 1H-NMR spectra and by elementary analysis. With ED50 values ranging from 6.0 to 71.5 mg/kg i.p. most of the compounds were several times more potent than acetaminophen (ED50 = 228.6 mg/kg i.p.) and noramidopyrine ((ED50 = 68.8 mg/kg i.p.) in the phenylbenzoquinone-induced writhing test (PBQ-test). Quantitative structure-activity relationships were accomplished by a Hansch analysis. The most active pyridazines 2h-j exhibited sedative properties from the dose of 25 mg/kg i.p. Their lack of activity in the hot plate test was in favour of peripherally acting agents. In the PBQ test, analgesic activity of 2h-j was antagonized by naloxone. However, their antinociceptive effect added up to those of 5-hydroxytryptophan when given in association with carbidopa. These results demonstrated that analgesic properties of pyridazine derivatives might involve a serotonergic pathway without interaction with opiodergic systems.

Synthesis and trazodone-like analgesic activity of 4-phenyl-6-aryl-2-[3-(4-arylpiperazin-1-yl)propyl]pyridazin -3-ones

A series of 4,6-diaryl pyridazinones, chemically related to trazodone, ws synthesized and evaluated for analgesic activity. With ED50 values ranging from 8.4 to 46.7 mg kg(-1) i.p. in the phenylbenzoquinone-induced writhing test (PBQ test), most compounds were several times more potent than acetaminophen (ED50 = 231.3 mg kg(-1) i.p.) and noramidopyrine (ED50 = 68.5 mg kg(-1) i.p.). A multiple linear regression analysis demonstrated a correlation between antinociceptive activity and lipophilicity, as well as electronic and steric factors. The most active pyridazinones 2c and 2j exhibited minimal sedative and neurotoxic effects at the dose of 25 mg kg(-1) i.p. They were devoid of activity in the hot plate test and their analgesic activity was not significantly reversed by naloxone in the PBQ test. The antinociceptive response induced by morphine (0.15 mg kg(-1) s.c.) in the PBQ test was greatly potentiated by 2c and 2j administered at the low doses of 1 and 2.5 mg kg(-1) i.p., respectively. On the other hand, their analgesic effects were enhanced synergistically by 5-hydroxytryptophan combined with carbidopa. All these data imply that a significant part of the antinociceptive effect induced by 2c and 2j may involve both opioid and serotonergic pathways. In addition, these two pyridazinones did not exhibit any antidepressant properties in the forced swimming test, nor did they potentiate yohimbine-induced toxicity.

Effect on free radical processes of some ascorbic acid analogues

Ascorbic acid, present in plasma from humans at concentrations of 50 to 200 mumol/l, has multiple antioxidant properties. Structural modification of this vitamin by the introduction of lipophilic moieties has allowed to the development of ascorbate esters and ethers active as free radical quenchers. Thus, a new series of ascorbic acid analogues possessing one or two aromatic rings was prepared in an attempt to synthesize potent antioxidants with lipophilic properties. Substituted 3-hydroxy furan-2 (5H)-ones and in some cases, dihydrofuro[3,4-b]pyrones were prepared. The synthesized compounds were evaluated for their antioxidant activity in vitro. So, 4-(4-methoxybenzoyl)-3-hydroxy-5-phenylfuran-2(5H)-one 3e (IC50 = 3.06 x 10(-4) M) was found to be the most effective in scavenging the superoxide anion, whereas 4-benzoyl-3-hydroxy-5-(3,4-dimethoxyphenyl)furan- 2(5H)-one 3d (IC50 = 1.38 x 10(-4) M) was the most active in inhibiting, lipid peroxidation.

[4-Arylpiperazine derivatives: a seedbed of drugs for various therapeutic indications]

The main focus of this review is the pharmacology and the therapeutic use of chemical related agents, the arylpiperazine derivatives. These compounds produce a variety of behavioural responses and pharmacological effects which directly and principally result from activation of serotonin systems. However, minor modifications in the chemical structure of these products involve important changes in affinity and selectivity for 5-HT receptors since it can also display significant affinity for dopaminergic, adrenergic or histaminergic receptors. The different arylpiperazine drugs therapeutically used are described as well as some compounds presently under investigation.

Synthesis of new serotonergic 2-substituted 4,6-diaryl pyridazin-3-ones

A series of 4,6-diaryl pyridazin-3-ones substituted in the 2-position by [4-(4-aryl piperazin-1-yl]-but-2-ynyl moieties was synthesized and evaluated for antidepressant activity. The structures of these new pyridazine derivatives were confirmed by IR, 1H-NMR spectra and by elementary analysis. At 150 mg/kg i.p., they induced little or no reduction of the duration of immobility of mice in the forced swimming test. Head twitches produced by L-5-hydroxytryptophan in mice pretreated with pargyline were significantly potentiated by most of the tested compounds. In addition, pyridazine derivatives did not antagonize reserpine-induced palpebral ptosis or enhance the toxic effects of yohimbine and were almost devoid of anticholinergic properties in mice.

Behavioural profile of two potential antidepressant pyridazine derivatives including arylpiperazinyl moieties in their structure, in mice

The potential antidepressant effects of two pyridazine derivatives, 5-benzyl 6-methyl 2-[4-(3-trifluoro-methyl phenyl) piperazin-1-yl] methylpyridazin-3-one (PC4) and 5-benzyl 6-methyl 2-[4-(3-chlorophenyl) piperazin-1-yl] methylpyridazin-3-one (PC13), were evaluated using classical psychopharmacological tests in mice. The intraperitoneal LD50 values of PC4 and PC13 were respectively 1125.8 and 429.6 mg kg-1. Only at intraperitoneal doses of 100 mg kg-1 did PC4 or PC13 significantly decrease locomotor activity. Both compounds (5-20 mg kg-1, i.p.) reduced the duration of immobility of mice in the forces swimming test, antagonized reserpine (2.5 mg kg-1, i.p.)-induced ptosis, and potentiated reserpine (2.5 mg kg-1, i.p.)-induced hypothermia. PC4 and PC13 (20 mg kg-1, i.p.) partly reversed hypothermia induced by low dose apomorphine (5 mg kg-1, s.c.) but were less effective for higher doses of apomorphine (16 mg kg-1, s.c.). At 200 mg kg-1, intraperitoneal PC13 enhanced the toxic effects of yohimbine (30 mg kg-1, s.c.), while PC4 was inactive. Head twitches produced either by L-5-hydroxytryptophan (4 mg kg-1, i.p.) in mice pretreated with pargyline (100 mg kg-1, i.p.) or by 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (3 mg kg-1, i.p.) were antagonized by both pyridazine derivatives (20 mg kg-1, i.p.). PC4 and PC13 showed analgesic properties in the phenylbenzoquinone-induced abdominal constriction test (5.0 < ED50 < 5.5 mg kg-1, i.p.) and in the hot-plate test (10 to 37% of analgesia at 10 mg kg-1, i.p.).(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis and anticonvulsant properties of new benzylpyridazine derivatives

Several 3-substituted pyridazines and a series of imidazo- and triazolopyridazines were synthesized and tested for anticonvulsant activity against maximal electroshock-induced seizures in mice. The most active derivatives, 3-ureidopyridazine 7 and triazolopyridazines 16, 18, 21, and 25 with oral ED50's that ranged from 6.2 to 22.0 mg/kg, were more extensively investigated by evaluating their ability to prevent chemically induced seizures and were compared with phenytoin, phenobarbital, sodium valproate, carbamazepine, and diazepam. 3-amino-7-(2,6-dichlorobenzyl)-6-methyltriazolo-[4,3-b]pyridazine (25) was also protective in the pentylenetetrazole-induced seizures test (ED50 = 76 mg/kg per os) and blocked strychnine-induced tonic extensor seizures (ED50 = 34.5 mg/kg per os). Furthermore, derivative 25 showed anticonvulsant effects on bicuculline- and yohimbine-induced seizures tests in mice. All these results suggest that the pharmacological activity of 25 is partly due to modifications of glycinergic and GABAergic transmission. Moreover, molecular modeling studies based on the antiepileptic drug lamotrigine and the most stable conformer of 25 show structural similarities between these two molecules. This conformer also agrees with the electronic tolerances and volume of benzodiazepine pharmacophore models.

Study of structure/activity relationships by multivariate statistical analysis in a series of triazaspirodecanediones with CNS activities

The CNS activities of thirteen triazaspirodecanediones have been compared by multivariate statistical analysis. The response parameters used in this study were spontaneous motor activity, potentiation of pentobarbital effect, anticonvulsant and anxiolytic activities. Pharmacological data were analyzed using two methods: (1) a factorial correspondence analysis; (2) an automatic analysis based first on a hierarchical clustering represented by a dendrogram and second on the minimum spanning tree method. The obtained results allow to imagine the synthesis of more specific compounds.

Synthesis of new 5-substituted pyrazolo[1,5-d][1,2,4]-triazine derivatives and their analgesic, anti-inflammatory and antipyretic properties

A series of 2-aryl-4-oxo-pyrazolo[1,5-d][1,2,4]triazines substituted in the 5-position by aminoalkyl or benzoyl moieties was synthesized and evaluated for analgesic activity. The structures of new triazine derivatives were confirmed by IR, 1H-NMR spectra and by elementary analysis. In the phenylbenzoquinone induced writhing test, only 3,3a-dihydropyrazolo triazines substituted by an arylpiperazinylmethyl group exhibited potent analgesic effect. In addition, these compounds possessed significant anti-inflammatory and antipyretic properties. A desaturation in 3,3a positions or other groups than arylpiperazinylmethyl moieties notably decreased analgesic effects.

Synthesis of Mannich bases of arylidenepyridazinones as analgesic agents

A series of 5-arylidenepyridazin-3-ones substituted in the 2-position by an arylpiperazinoalkyl moiety (2-16) was synthesized and evaluated for analgesic activity. In the phenylbenzoquinone-induced writhing test, Mannich bases 2-14 were the most active compounds (6.1 < or = ED50 < or = 43.0 mg/kg, orally; ED50 is the half-maximal effective dose). Pyridazinones 8 and 9, with a 3-chlorophenylpiperazinomethyl substituent, also exhibited significant anti-inflammatory and antipyretic effects. The activities in the phenylbenzoquinone-induced writhing test were subjected to a Hansch analysis, and a significant correlation with lipophilicity and Hammett's constants was obtained.

Synthesis and aldose reductase inhibitory activity of triazine derivatives possessing acetic acid group

N-Acetic acid derivatives of 6-aryl-pyrazolo-triazin-4-ones were synthesized for evaluation as new aldose reductase inhibitors. The intrinsic activity of each compound was assessed by measuring the inhibition of enzymatic activity in an isolated pig lens enzyme preparation. All the prepared compounds exhibited a significant in vitro aldose reductase inhibitory effect (10(-6) M less than or equal to IC50 less than or equal to 10(-4) M). Furthermore, biological activity (log 1/IC50) for most of the data sets could be correlated directly to electronic and steric parameters. Finally, spatial configuration of the most active derivative 6c (IC50 = 2 x 10(-6) M) was compared with that of tolrestat and with pharmacophor requirements of the aldose reductase inhibitor site using a molecular modeling system.

Studies on immunostimulating derivatives: synthesis of some pyrrolo[1,2-c]pyrimidines

In a search for potential immunomodulating agents novel pyrrolo[1,2-c]pyrimidines were synthesized and their structures elucidated by spectroscopic means. Unfortunately, most of them were cytotoxic and devoid of effects on T lymphocyte lymphoblastic transformation. Furthermore, they were inactive in the locomotor activity test in mice.

Anticonvulsant activity of 3-oxo-5-substituted benzylidene-6-methyl-(4H)-2-pyridazinylacetamides and 2-pyridazinylacetylhydrazides

A series of 3-oxo-5-substituted-benzylidene-6-methyl-(4H)-2- pyridazinylacetamides and 2-pyridazinylacetylhydrazides were synthesized and evaluated for anticonvulsant activity against electrically and chemically induced seizures. In the maximal electroshock-induced seizures test, most of the derivatives showed an anticonvulsant effect better than that of sodium valproate, a commonly used anticonvulsant drug. At 100 mg/kg orally, compounds 5a and 5b respectively protected 50 and 60% of the mice against pentylentetrazole-induced seizures. In addition, these two derivatives showed significant anticonvulsant properties at doses that did not produce ataxia or sedation. The title compounds were also tested for their ability to antagonize convulsions induced by bicuculline and strychnine. Their effect on tremors induced by oxotremorine in mice was also evaluated.

Aminopyridazine derivatives and TXA2-PGI2 balance

Experiments carried out under the conditions adopted showed the strong affinity of aminopyridazine derivatives for the eicosanoids TXA2 and PGI2. But this affinity depended on the chemical structure of the molecule: a small change in the radical grafted onto the pyridazine ring could completely modify the pharmacological activity of the molecule. Consequently it should be possible to control the properties of pyridazine derivatives according to pharmacological needs. Thus: --pyridazin-3-one derivatives were mainly active on TXA2 biosynthesis: 2-aminoalkyl 5-arylidene 6-methyl (4H) pyridazin-3-ones inhibited the TXA2-synthesizing activity of cardiac tissue whereas 3-amino 4,6-diaryl pyridazin-3-ones were specific inhibitors of the TXA2 synthetase in vitro, but these effects were weak. --pyridazine derivatives were devoid of any effect on the TXA2-synthesizing activity of cardiac tissue: they acted on either TXA2 synthetase or PGI2 synthetase according to the radicals grafted onto the pyridazine ring. --none of the compounds under study was active on the PGI2-synthesizing activity of cardiac tissue.

Synthesis of 6-[(4-imidazol-1-yl)-phenyl]-4-phenyl 4,5-dihydro-2H-pyridazin-3-one: a potential blood platelet aggregation inhibitor

A new 4,5 diaryl pyridazin-3-one, an analogue of imazodan and Cl-930 was prepared starting from conveniently available chalcone. The resulting derivative was tested in order to determine the area of pharmacological activity. This compound was devoid of positive inotropic effects but showed an important inhibition of PAF-acether induced blood platelet aggregation in vitro with a Cl50 value of 3,4 microM. Ex vivo, anti-aggregating effect against PAF-acether was less important with a DE50 value of 63 mg/kg per os.

Comparative effects of some 3-amino 4,6-diarylpyridazines on the biosynthesis in vitro of TXA2 and PGI2- and on the TXA2- and PGI2-synthesizing activities of cardiac tissue

Some 3-amino 4,6-diarylpyridazine derivatives were tested for their effects on TXA2 and PGI2 biosyntheses in vitro and on the TXA2- and PGI2-synthesizing activities of cardiac tissue. Horse platelet and aorta microsomes were used as sources of thromboxane and prostacyclin synthetases respectively. The TXA2- and PGI2-synthesizing activities of cardiac tissue were studied on isolated perfused rabbit hearts (the heart microsomes being used both as TXA2 synthetase and PGI2 synthetase sources). TXB2 and 6-keto PGF1 alpha were determined by RIA. Among the compounds under study, 3-morpholino 4,6-diphenylpyridazine (III) was shown to inhibit specifically the TXA2 synthetase. Substitution of the morpholino group by a dimethylamino one (I) reinforced the inhibiting effects on TXA2 synthetase but it also revealed a slight anti-prostacyclin synthetase action of the molecule. Replacement of 3-morpholino moieties by either a 3-hydrazino (IV), or a 2-dimethylaminoethylamino (V), or a 2-morpholinoethylamino group (VI) abolished completely the effects of the molecule on TXA2 and PGI2 synthetases. Likewise the addition of chlorine on the para-position on the phenyl ring of I neutralized all its inhibitory effects both on TXA2 and PGI2 synthetases in vitro. None of the 3-amino 4,6-diarylpyridazine derivatives was active on either the TXA2- or PGI2-synthesizing activities of cardiac tissue.

Synthesis and pharmacological evaluation of N-substituted 4,6-diaryl-3-pyridazinones as analgesic, antiinflammatory and antipyretic agents

The synthesis and the pharmacological evaluation of 19 new 4,6-diaryl-3-pyridazinones are reported. All compounds were screened for analgesic, antiinflammatory and antipyretic activities. Introduction of an arylpiperazinomethyl moiety in the 2-position of the pyridazinone ring resulted in the most potent activities. Compounds 2a, 2b, 2h and 2i exhibited a higher analgesic activity than did aspirin or noramidopyrine in the hot plate test.

[Synthesis, antisecretory, and anti-ulcer activity of new 5-arylidene-2-ureidoalkyl-3-pyridazinones]

By addition of methylisocyanate to 5-arylidene 2-aminoalkyl 3-pyridazinones a series of derivatives substituted in the 2-position by an ureidoalkyl moiety was obtained in good yields. Gastric antisecretory and anti-ulcer activities of these new compounds were evaluated. The influence of the substituents attached to the pyridazine ring was discussed.

[Synthesis and antidepressive effects of diaryl-4,6-amino-3-pyridazine analogs of minaprine]

The reaction of 3-chloro pyridazines with various amines led to a series of minaprine analogues. Most of them exhibited significant antidepressant activity. The influence of the substituents attached to the pyridazine ring was discussed.

A selective inhibitor of thromboxane synthetase activity of rabbit heart tissue: a pyridazinic derivative

The effects of 2-(2 dimethylaminoethyl) 5-benzylidene 6-methyl (2H,4H)-3-pyridazinone (III) were studied on the biosynthesis of TXA2 and PGI2 in vitro the TXA2 and PGI2 synthetase activity of heart tissue. Biosyntheses of TXA2 and PGI2 were carried out using arachidonic acid as a substrate and horse platelet and aorta microsomes as sources of TXA2 and PGI2 synthetases respectively. TXB2 and 6-keto PGF1 alpha were determined by RIA. III--did not significantly modify either the biosynthesis of PGI2 in vitro or the PGI2 synthetase activity of heart tissue. did not significantly inhibit TXA2 biosynthesis in vitro but markedly reduced the TXA2 synthetase activity of heart tissue: for a microsomal fraction concentration of 100 micrograms protein, the ID50 was 6.37 X 10(-5) M +/- 1.29 X 10(-8) M. Thus III behaves as a specific inhibitor of the TXA2 synthetase activity of heart tissue and could have a beneficial use in therapeutics.