Design and synthesis of Mannich base-type derivatives containing imidazole and benzimidazole as lead compounds for drug discovery in Chagas Disease.

The protozoan parasite Trypanosoma cruzi is the causative agent of Chagas disease, the most important parasitic infection in Latin America. The only treatments currently available are nitro-derivative drugs that are characterised by high toxicity and limited efficacy. Therefore, there is an urgent need for more effective, less toxic therapeutic agents. We have previously identified the potential for Mannich base derivatives as novel inhibitors of this parasite. To further explore this family of compounds, we synthesised a panel of 69 new analogues, based on multi-parametric structure-activity relationships, which allowed optimization of both anti-parasitic activity, physicochemical parameters and ADME properties. Additionally, we optimized our in vitro screening approaches against all three developmental forms of the parasite, allowing us to discard the least effective and trypanostatic derivatives at an early stage. We ultimately identified derivative 3c, which demonstrated excellent trypanocidal properties, and a synergistic mode of action against trypomastigotes in combination with the reference drug benznidazole. Both its druggability and low-cost production make this derivative a promising candidate for the preclinical, in vivo assays of the Chagas disease drug-discovery pipeline.

In vitro and in vivo evaluation of the antimalarial MMV665831 and structural analogs.

Antimalarial candidates possessing novel mechanisms of action are needed to control drug resistant Plasmodium falciparum. We were drawn to Malaria Box compound 1 (MMV665831) by virtue of its excellent in vitro potency, and twelve analogs were prepared to probe its structure-activity relationship. Modulation of the diethyl amino group was fruitful, producing compound 25, which was twice as potent as 1 against cultured parasites. Efforts were made to modify the phenolic Mannich base functionality of 1, to prevent formation of a reactive quinone methide. Homologated analog 28 had reduced potency relative to 1, but still inhibited growth with EC50 ≤ 200 nM. Thus, the antimalarial activity of 1 does not derive from quinone methide formation. Chemical stability studies on dimethyl analog 2 showed remarkable hydrolytic stability of both the phenolic Mannich base and ethyl ester moieties, and 1 was evaluated for in vivo efficacy in P. berghei-infected mice (40 mg/kg, oral). Unfortunately, no reduction in parasitemia was seen relative to control. These results are discussed in the context of measured plasma and hepatocyte stabilities, with reference to structurally-related, orally-efficacious antimalarials.

Synthesis and pharmacological evaluation of novel N-Mannich bases derived from 5,5-diphenyl and 5,5-di(propan-2-yl)imidazolidine-2,4-dione core.

The aim of this study was to design and synthesize two series of N-Mannich bases with imidazolidine-2,4-dione core as a potential anticonvulsant with reduced toxicity and broad antiseizure activity. Preliminary screening revealed that the majority of synthesized compounds were effective in the maximal electroshock seizure (MES) and/or subcutaneous pentylenetetrazole (scPTZ) test. The most active in vivo compound, 18 (3-((4-methylpiperazin-1-yl)methyl)-5,5-diphenylimidazolidine-2,4-dione), exhibited an ED50 value comparable to that of phenytoin in the MES test (38.5 mg/kg vs 28.1 mg/kg), and more importantly, it showed four times higher potency than phenytoin in the 6 Hz test (12.2 mg/kg vs > 60 mg/kg). Additionally, 18 exhibited antiallodynic properties in the von Frey test in neuropathic (oxaliplatin-treated) mice. Compound 18 also demonstrated a broader spectrum of anticonvulsant activity than phenytoin and showed statistically significant antinociceptive properties in selected models of chronic pain.

Novel Mannich-bases as Potential Anticonvulsants: Syntheses, Characterization and Biological Evaluation.

BACKGROUND: Mannich bases are known to be an important pharmacophore or bioactive leads in the synthesis of various potential agents that have a variety of therapeutic activities like anticancer, antipsychotic, anticonvulsant, antimalarial, anti-inflammatory, antibacterial and so forth. Thus, in the present research, conjugation of moieties like 1,5-benzoxazepines and 1,5-benzothiazepines with secondary amines like piperazine, methyl piperazine and morpholine was carried out in a Mannich base with an anticipation of good anticonvulsant activity. OBJECTIVE: Synthesis, characterization, structure activity relationship and anticonvulsant activity of the Mannich bases of 1,5-benzothiazepine and 1,5-benzoxazepine derivatives. METHODS: All the derivatives were synthesized in three steps. In the first step, substituted 4-hydroxy chalconylbenzene was synthesized by the reaction of 4-hydroxyacetophenone and substituted benzaldehyde, in the presence of potassium hydroxide. In the second step, 2,3-dihydro- 1,5- benzothiazepines and 2,3-dihydro-1,5-benzoxazepines were synthesized by the reaction of 2- thio/aminophenol with chalcones in the presence of glacial acetic acid. In the third step, these compounds finally underwent Mannich reaction with different secondary amines to the respective title compounds. All the synthesized derivatives were characterised and evaluated for anticonvulsant activity using MES (Maximal Electroshock Induced Seizure) and INH (Isoniazide Induced Convulsion) models. RESULTS: The synthesized derivatives were found to be more active in the MES model than INH model, with phenytoin and diazepam being the standards respectively. Accordingly, the mode of action of the synthesized compounds may be similar to phenytoin. The methyl piperazine containing compound, at a dose of 30 mg/kg., was found to be the most active and promising compound in the series. CONCLUSION: The benzothiazepine derivatives showed better anticonvulsant activity than the benzoxazepines derivatives.

Search for new potential anticonvulsants with anxiolytic and antidepressant properties among derivatives of 4,4-diphenylpyrrolidin-2-one.

BACKGROUND: The aim of this study was to synthesize a series of new N-Mannich bases derived from 4,4-diphenylpyrrolidin-2-one having differently substituted 4-phenylpiperazines as potential anticonvulsant agents with additional (beneficial) pharmacological properties. METHODS: The target compounds 8-12 were prepared in one step from the 4-substituted phenylpiperazines, paraformaldehyde, and synthesized 4,4-diphenylpyrrolodin-2-one (7) by a Mannich-type reaction. The obtained compounds were assessed and tested for their anticonvulsant activity in two screening mouse models of seizures, i.e., the maximal electroshock (MES) test and in the subcutaneous pentylenetetrazole (scPTZ) test. The effect of these compounds on animals' motor coordination was measured in the rotarod test. A selected 4,4-diphenyl-1-((4-phenylpiperazin-1-yl)methyl)pyrrolidin-2-one (8) was evaluated in vivo for its anxiolytic- and antidepressant-like properties. Its impact on animals' locomotor activity was also evaluated. RESULTS: Compound 8 showed protection (25%) in the MES and in the scPTZ tests at the dose of 100mg/kg and was not neurotoxic. In the four-plate test, compound 8 at the dose of 30mg/kg showed a statistically significant (p<0.05) anxiolytic-like activity. In the forced swim test, it reduced the immobility time by 24.3% (significant at p<0.05), which indicates its potential antidepressant-like properties. In the locomotor activity test, compound 8 significantly reduced animals' locomotor activity by 79.9%. CONCLUSION: The results obtained make a new derivative of 4,4-diphenyl-1-((4-phenylpiperazin-1-yl)methyl)pyrrolidin-2-one (8) a promising lead structure for further development.

Evaluation of anticonvulsant and antinociceptive properties of new N-Mannich bases derived from pyrrolidine-2,5-dione and 3-methylpyrrolidine-2,5-dione.

The aim of the present experiments was to examine anticonvulsant activity of new pyrrolidine-2,5-dione and 3-methylpyrrolidine-2,5-dione derivatives in animal models of epilepsy. In addition, the possible collateral antinociceptive activity was assessed. Anticonvulsant activity was investigated in the electroconvulsive threshold (MEST) test and the pilocarpine-induced seizure models in mice. Antinociceptive activity was examined in the hot plate and the formalin tests in mice. Considering the drug safety evaluation, the Vibrio harveyi test was used to estimate anti/mutagenic activity. To determine the plausible mechanism of anticonvulsant action, for two chosen compounds (12 and 23), in vitro binding assays were carried out. All of the tested compounds revealed significant anticonvulsant activity in the MEST test. Compounds 12 and 23 displayed anticonvulsant effect also in pilocarpine-induced seizures. Four of the tested compounds (12, 13, 15, and 24) revealed analgesic activity in the hot plate test as well as in the first phase of the formalin test, and all of them were active in the second phase of the formalin test. The possible mechanism of action of compounds 12 and 23 is the influence on the neuronal voltage-sensitive sodium and L-type calcium channels. The obtained results indicate that in the group of pyrrolidine-2,5-diones, new anticonvulsants with collateral analgesic properties can be found.

Design, synthesis and anticonvulsant properties of new N-Mannich bases derived from 3-phenylpyrrolidine-2,5-diones.

The synthesis and anticonvulsant properties of new N-Mannich bases of 3-phenyl- (9a-d), 3-(2-chlorophenyl)- (10a-d), 3-(3-chlorophenyl)- (11a-d) and 3-(4-chlorophenyl)-pyrrolidine-2,5-diones (12a-d) were described. The key synthetic strategies involve the formation of 3-substituted pyrrolidine-2,5-diones (5-8), and then aminoalkylation reaction (Mannich-type) with formaldehyde and corresponding secondary amines, which let to obtain the final compounds 9a-d, 10a-d, 11a-d and 12a-d in good yields. Initial anticonvulsant screening was performed in mice (ip) using the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizures tests. The most effective compounds in mice were tested after oral administration in rats. The acute neurological toxicity was determined applying the minimal motor impairment rotarod test. The in vivo results revealed that numerous compounds were effective especially in the MES test (model of human tonic-clonic seizures). The most active in the MES seizures in rats was 1-[(4-benzyl-1-piperidyl)methyl]-3-(2-chlorophenyl)pyrrolidine-2,5-dione (10c) which showed ED50 value of 37.64mg/kg. It should be stressed that this molecule along with 9a, 9d and 10d showed protection in the psychomotor seizure test (6-Hz), which is known as an animal model of therapy-resistant epilepsy. Furthermore compounds 9a, 9d and 10d were also tested in the pilocarpine-induced status prevention (PISP) test to assess their potential effectiveness in status epilepticus. For the most promising molecule 9d an influence on human CYP3A4 isoform of P-450 cytochrome was studied in vitro.

Synthesis and anticonvulsant activity of new n-mannich bases derived from 5-cyclopropyl-5-phenyl-hydantoins.

Synthesis, physicochemical and anticonvulsant properties of new N-Mannich bases 3-24 derived from 5-cyclopropyl-5-phenyl- and 5-cyclopropyl-5-(4-chlorophenyl)-hydantoins were described here. Initial anticonvulsant screening was performed using intraperitoneal (i.p.) maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizures tests. Selected derivatives were also screened in the 6-Hz test. The neurotoxicity was determined applying the rotorod test. The pharmacological results revealed that the majority of compounds were effective in MES and/or scPTZ tests. The quantitative studies after oral administration into rats showed that several molecules were more potent than phenytoin and ethosuximide which were used as reference antiepileptic drugs. From the whole series the most active was 3-[(4-phenylpiperazin-1-yl)-methyl]-5-cyclopropyl-5-phenyl-imidazolidine-2,4-dione (3) with the ED(50) value of 5.29 mg/kg in the MES test.

Design, synthesis, and anticonvulsant activity of new N-Mannich bases derived from spirosuccinimides and spirohydantoins.

The synthesis and anticonvulsant properties of new N-Mannich bases of [7,8-f]benzo-2-aza-spiro[4.5]decane-1,3-diones (5a-h) and [7,8-f]benzo-1,3-diaza-spiro[4.5]decane-2,4-diones (7a-h) were described. Initial anticonvulsant screening was performed using intraperitoneal (ip) maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizures tests. The neurotoxicity was determined applying the rotarod test. The majority of compounds were effective in the MES or/and scPTZ screen. The quantitative studies showed that several molecules were more potent than phenytoin, used as reference drug. Selected derivatives were screened in the 6-Hz test and also assessed for potential activity against nerve agents using the Pilocarpine Induced Status Prevention model. To explain the possible mechanism of anticonvulsant action, for chosen active derivatives, their influence on voltage-dependent Na(+) channel were tested in vitro.

Synthesis and anticonvulsant properties of new Mannich bases derived from 3-aryl-pyrrolidine-2,5-diones. Part 1.

A series of new Mannich bases of N-[(4-arylpiperazin-1-yl)-methyl]-3-(chlorophenyl)-pyrrolidine-2,5-diones 10-23 have been synthesized and evaluated for their anticonvulsant activity in maximum electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure threshold tests. Their neurotoxicity was determined using a rotorod screen. Several molecules showed a promising anticonvulsant profile especially in the MES-test. In this model of seizures, the most active were N-[{4-(4-chlorophenyl)-piperazin-1-yl}-methyl]-3-(3-chlorophenyl)-pyrrolidine-2,5-dione 16 and N-[{4-(3-trifluoromethylphenyl)-piperazin-1-yl}-methyl]-3-(3-chlorophenyl)-pyrrolidine-2,5-dione 17 with ED(50) values of 21.4 mg/kg and 28.83 mg/kg, respectively. Selected derivatives 10, 14, and 16 were tested in the psychomotor seizure 6-Hz test from which N-[{4-(2-chlorophenyl)-piperazin-1-yl}-methyl]-3-(2-chlorophenyl)-pyrrolidine-2,5-dione 10 revealed the highest protection with an ED(50) of 78 mg/kg. Compounds 10, 12, and 17 were also tested in the pilocarpine-induced status PIPS test. Furthermore, 17 was examined in the hippocampal kindling screen after i. p. administration to rats.

Janus kinase 3: a novel target for selective transplant immunosupression.

Existing immunosuppressants inhibit lymphocyte activation and T cell cytokine signal transduction pathways, reducing the rate of acute rejection episodes to < 10%. However, the widespread tissue distribution of their molecular targets engenders pleiotropic toxicities. One strategy to address this problem seeks to identify compounds that selectively inhibit a target restricted in distribution to the lymphoid system. Janus kinase (Jak) 3 is such a molecule; it mediates signal transduction via the gamma common chain of lymphokine surface receptors. Disruption of this lymphoid-restricted enzyme would not be predicted to produce collateral damage in other organ systems. Development of selective Jak3 inhibitors has been difficult due to crossreactivity with its homologue, Jak2. In contrast to all other putative antagonists, which are discussed in detail herein, one Jak3 inhibitor, NC1153, shows at least 40-fold greater selective inhibition for Jak3 than for Jak2, is robustly synergistic with calcineurin antagonists, and, either alone or in combination with cyclosporin, produces no adverse effects in rodents preconditioned to be at heightened risk for nephrotoxicity, bone marrow suppression, or altered lipid metabolism.

[New isatin-derived hydrazones and Mannich bases with possible biological activity]. / Noi hidrazone si baze Mannich derivate de la isatina, cu eventuala activitate biologica.

The paper presents a synthesis of six new Mannich bases, five hydrazones derived from 1-piperidino-methyl-5-R-isatin and three copper complex compounds of 3-(3'-R-phenyl-pyridazinil-hydrazone)-indoline-2-ones (R=H, CH3, OCH3). The structure of the new compounds was confirmed by the results of the elementary and spectral analysis. Pharmacodynamic studies indicated that copper complex compounds present effective biological properties. Thus, it can be seen that the experimental carrageenan-induced inflammatory oedema was 58.3% inhibited by the complex V (R=CH3) after oral administration. Antimicrobial tests revealed that only compound V (R=OCH3) shows a moderate antimicrobial activity against the gram-positive and gram-negative bacteria, used in the test.

In-vitro and in-vivo susceptibility of Aspergillus fumigatus to a novel conjugated styryl ketone.

We investigated the in-vitro and in-vivo susceptibility of Aspergillus fumigatus to the novel conjugated styryl ketone NC1175 and the results were compared with those obtained for amphotericin B and itraconazole. All 20 clinical isolates of A. fumigatus examined were susceptible to NC1175 (MIC = 5.54 +/- 2.48 mg/L; range 2.92-11.68 mg/L), and the minimum lethal concentration (MLC) was only twice the MIC, suggesting that NC1175 is fungicidal. The mean MIC values of amphotericin B (1.22 +/- 0.58 mg/L; range 0.5-4 mg/L) and itraconazole (0.37 +/- 0.11 mg/L; range 0.125-0.5 mg/L) were approximately nine- and 22-fold, respectively, lower than that of NC1175. Both amphotericin B-resistant (n = 18) and itraconazole-resistant (n = 28) isolates of A. fumigatus were as susceptible to NC1175 as amphotericin B-, and itraconazole-susceptible isolates. Kill curve experiments revealed that NC1175 at 23.35 mg/L (approximately four times the MIC) killed > or = 99% of conidia within 24 h of exposure to the drug. The in-vivo susceptibility of A. fumigatus to NC1175 was investigated using a murine pulmonary aspergillosis model. Treatment of infected mice with amphotericin B or NC1175 did not result in significant improvement of the mean survival (amphotericin B, 7.05 +/- 0.07 days; NC1175, 6.65 +/- 1.25 days) of the animals compared with that of the placebo group (7.21 +/- 1.20 days). However, semiquantitative organ culture revealed that clearance of A. fumigatus occurred in 16.6%, 50% and 66.6% of the mice treated with placebo, NC1175 and amphotericin B, respectively (P value for the control and the treated groups <0.01). These results suggest that NC1175 has in-vivo and in-vitro activity against A. fumigatus and can be used as a prototypic molecule for further development as an antifungal agent.

Antileishmanial agents: synthesis of allopurinol prodrugs for oral administration

Synthesis of six prodrugs of allopurinol (4-hydroxypyrazolo-(3,4-d)pyrimidine) is described. These compounds were given orally to male and female BALB/C (sensitive) and C57BL/6 (partially resistant) strains of mice, wich had been previously infected with Leishmania mexicana. The results show that at end of the treatment there was weak regression of lesions confirmed through measurement of nodule diameter in the infected animals

The chemotherapy of rodent malaria. XLVII. Studies on pyronaridine and other Mannich base antimalarials.

The activities of Mannich base antimalarials, including pyronaridine, have been explored against drug-sensitive (Plasmodium berghei N) and chloroquine-resistant (Plasmodium yoelii NS) rodent malaria parasites in vivo. Lines of these parasites have been developed with resistance to pyronaridine, amodiaquine, or WR 228,258. The responses and patterns of cross-resistance of these lines to Mannich bases and other blood schizontocides are inconsistent. It is concluded that some Mannich bases may prove still to be of value inthe treatment of chloroquine-resistant Plasmodium falciparum infection.

The in vitro and in vivo antimalarial activity of some Mannich bases derived from 4-[7'-bromo (and chloro)-1',5'-naphthyridin-4'-ylamino]phenol and 4-(7'-trifluoromethylquinolin-4'-ylamino)phenol.

A series of di-Mannich bases derived from 4-[7'-bromo (and chloro)-1',5'-naphthyridin-4'-ylamino]phenol and 4-(7'-trifluoromethylquinolin-4'-ylamino)phenol were assayed for activity against chloroquine-sensitive and chloroquine-resistant isolates of cultured Plasmodium falciparum using the inhibition of uptake of radiolabelled hypoxanthine. A number of the 4-(7'-trifluoromethylquinolinyl-amino)phenols showed statistically superior activity to chloroquine and amodiaquine against both isolates. Analysis of the antimalarial activity of some of these compounds against Plasmodium berghei in mice following oral administration again demonstrated activity equal or superior to that of the established antimalarials against a chloroquine-sensitive strain, and in some cases appreciably superior activity against a chloroquine-resistant strain.

5-(2-Oxo-3-indolinylidene)thiazolidine-2,4-dione-1,3-di-Mannich base derivatives: synthesis and evaluation for antileukemic activity.

A novel series of 5-(2-oxo-3-indolinylidene)thiazolidine-2,4-dione, having the 1- and 3-positions of the isatin and thiazolidine rings respectively, substituted by various Mannich bases, was prepared. Five compounds were evaluated for antileukemic activity against P388 lymphocytic leukemia in the mouse. The di-Mannich base with a dimethylamino component exhibited the highest activity of the tested compounds. Introduction of bromine into the aromatic moiety of isatin ring (position 5) increased the activity of the parent molecule to a smaller extent.

bis-Mannich bases of styryl ketones as antileukemic agents.

A novel series of bis-Mannich bases have been synthesized and evaluated against P388 lymphocytic leukemia in mice. Two compounds showed a perceptible beneficial response in this screen and all the compounds displayed marked murine toxicity. A representative compound inhibited respiration in mitochondria isolated from rat and mouse liver cells by 90% approximately at a dose of 2.5 mumol and it caused a small elevation in mouse liver glutathione equivalent concentrations at 5 mg/kg.