Tomasz Plech

Synthesis and antimicrobial activity of thiosemicarbazides, s-triazoles and their Mannich bases bearing 3-chlorophenyl moiety

A fast and efficient synthesis of some 1,4-disubstituted thiosemicarbazide derivatives is described. The reaction of 3-chlorobenzoic acid hydrazide with various aryl isothiocyanates gave thiosemicarbazide derivatives (1-11) in good yield. The cyclization of compounds (1-11) in the presence of 2% NaOH resulted in the formation of compounds (12-22) containing the 1,2,4-triazole ring. A series of new Mannich bases (23-33) related to the structure of 1,2,4-triazole has been also synthesized. All of these compounds were tested for their in vitro antibacterial activity against the reference strains of aerobic bacteria - 6 Gram-positive and 3 Gram-negative ones; 12 Staphylococcus aureus clinical isolates were also examined. An attempt was made to clarify the influence of the nature/position of substituents on antibacterial activity of compounds described.

Synthesis, characterization and preliminary anticonvulsant evaluation of some 4-alkyl-1,2,4-triazoles.

Designed and synthesized 4-alkyl-1,2,4-triazole-3-thione derivatives showed significant anticonvulsant activity, determined in the maximal electroshock-induced seizure (MES) test. The chemical structure of all new compounds was confirmed by spectral methods ((1)H NMR, (13)C NMR, IR, MS). A sensitive and selective method was elaborated for the determination of the anticonvulsant compounds levels in mice brain tissue, based on HPLC with diode array detector (DAD). Chromatographic tests showed that lack of anticonvulsant effect of two derivatives (15, 16) with long alkyl chains at N-4 position of the 1,2,4-triazole ring was due to the inability to cross the blood-brain barrier (BBB).

Synthesis and in vitro activity of 1,2,4-triazole-ciprofloxacin hybrids against drug-susceptible and drug-resistant bacteria

A series of novel 1,2,4-triazole-ciprofloxacin hybrids was designed, synthesised and evaluated in vitro against drug-susceptible and drug-resistant bacteria. A significant part of the compounds obtained showed antibacterial activity higher than the activity of ciprofloxacin, both towards Gram-positive and Gram-negative species. Despite relatively small number of synthesised derivatives, it was possible to observe important dependences between their structure and activity.

Search for factors affecting antibacterial activity and toxicity of 1,2,4-triazole-ciprofloxacin hybrids.

A series of 1,2,4-triazole-based compounds was designed as potential antibacterial agents using molecular hybridization approach. The target compounds (23-44) were synthesized by Mannich reaction of 1,2,4-triazole-3-thione derivatives with ciprofloxacin (CPX) and formaldehyde. Their potent antibacterial effect on Gram-positive bacteria was accompanied by similarly strong activity against Gram-negative strains. The toxicity of the CPX-triazole hybrids for bacterial cells was even up to 18930 times higher than the toxicity for human cells. The results of enzymatic studies showed that the antibacterial activity of the CPX-triazole hybrids is not dependent solely on the degree of their affinity to DNA gyrase and topoisomerase IV.

Effect of 4-(4-bromophenyl)-5-(3-chlorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione on the anticonvulsant action of different classical antiepileptic drugs in the mouse maximal electroshock-induced seizure model.

The aim of this study was to determine the effects of 4-(4-bromophenyl)-5-(3-chlorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (TP4-a new S-triazole derivative possessing anticonvulsant properties in preclinical studies) on the protective action of four different classical antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) against maximal electroshock-induced seizures in mice. Results indicate that TP4 administered intraperitoneally at doses of 75 and 100 mg/kg significantly elevated the threshold for electroconvulsions in mice. TP4 at doses of 12.5, 25, 37.5 and 50 mg/kg had no impact on the threshold for electroconvulsions in mice. Moreover, TP4 (50 mg/kg) significantly enhanced the anticonvulsant activity of carbamazepine, phenobarbital and valproate, but not that of phenytoin in the maximal electroshock seizure test in mice. TP4 at 25 mg/kg significantly potentiated the anticonvulsant action of carbamazepine, but not that of phenobarbital, phenytoin and valproate in the mouse maximal electroshock-induced seizure model. Pharmacokinetic experiments revealed that TP4 significantly elevated total brain concentrations of carbamazepine and valproate, having no impact on total brain concentrations of phenobarbital in mice. In conclusion, the enhanced anticonvulsant action of phenobarbital by TP4 was probably pharmacodynamic in nature and, therefore, the combination of TP4 with phenobarbital is worthy of consideration while extrapolating the results from this study into clinical settings. The enhanced anticonvulsant action of carbamazepine and valproate by TP4 in the mouse maximal electroshock-induced seizure model was associated with pharmacokinetic increases in total brain concentrations of the antiepileptic drugs in mice. The combination of TP4 with phenytoin was neutral from a preclinical point of view.

Determination of the Primary Molecular Target of 1,2,4-Triazole-Ciprofloxacin Hybrids

We have synthesized and examined the antibacterial activity, toxicity and affinity towards bacterial type II topoisomerases of a series of 1,2,4-triazole-ciprofloxacin hybrids. A number of these compounds displayed enhanced activity against Gram-positive and Gram-negative bacteria when compared to ciprofloxacin. The toxic concentrations of the obtained derivatives, evaluated on HEK-293 cells using MTT assay, were much higher than concentrations required to produce antibacterial effect. Finally, the results of enzymatic studies showed that the analyzed compounds demonstrated other preferences as regards primary and secondary molecular targets than ciprofloxacin.

Synthesis and In Vitro Antiproliferative Activity of Thiazole-Based Nitrogen Mustards: The Hydrogen Bonding Interaction between Model Systems and Nucleobases

Synthesis, characterization and investigation of antiproliferative activity of eight thiazole-based nitrogen mustard against human cancer cells lines (MV4-11, A549, HCT116 and MCF-7) and normal mouse fibroblast (BALB/3T3) are presented. Their structures were determined using NMR, FAB MS, HRMS and elemental analyses. Among the derivatives, 3a, 3b, 3e and 3h were found to exhibit high activity against human leukemia MV4-11 cells with IC50 values of 0.634-3.61 µg/ml. The cytotoxic activity of compound 3a against BALB/3T3 cells is up to 40 times lower than against cancer cell lines. Our data indicated also that compound 3e had very strong activity against MCF-7 and HCT116 with IC50 equal to 2.32 µg/ml and 2.81 µg/ml, respectively. Their activity was similar to the activity of cis-platin, which is clinically used as anticancer drug in the treatment of human solid tumours. We also perform quantum chemical calculation of interaction and binding energies in complexes of model systems and 3e with DNA bases. Interaction of real drug 3e with guanine is much stronger than with the remaining nucleobases, and the strongest among all investigated complexes. Computer simulations were performed with ATP-binding domain and DNA-binding site of hTopoII. Compounds 3a-h were recognized as potential inhibitors of hTopoII.

1,4-Disubstituted Thiosemicarbazide Derivatives are Potent Inhibitors of Toxoplasma gondii Proliferation

A series of 4-arylthiosemicarbazides substituted at the N1 position with a 5-membered heteroaryl ring was synthesized and evaluated in vitro for T. gondii inhibition proliferation and host cell cytotoxicity. At non-toxic concentrations for the host cells all studied compounds displayed excellent anti-parasitic effects when compared to sulfadiazine, indicating a high selectivity of their anti-T. gondii activity. The differences in bioactivity investigated by DFT calculations suggest that the inhibitory activity of 4-aryl-thiosemicarbazides towards T. gondii proliferation is connected with the electronic structure of the molecule. Further, these compounds were tested as potential antibacterial agents. No growth-inhibiting effect on any of the test microorganisms was observed for all the compounds, even at high concentrations.

Influence of 5-(3-chlorophenyl)-4-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione on the anticonvulsant action of 4 classical antiepileptic drugs in the mouse maximal electroshock-induced seizure model

BACKGROUND The aim of this study was to determine the effects of 5-(3-chlorophenyl)-4-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (TP10) on the protective action of 4 classical antiepileptic drugs - carbamazepine, phenobarbital, phenytoin and valproate - against maximal electroshock-induced seizures in mice. METHODS Tonic hind limb extension (seizure activity) was evoked in adult male albino Swiss mice by an electric current (sine-wave, 25 mA, 500 V, 50 Hz, 0.2 s stimulus duration) delivered via auricular electrodes. Acute adverse-effect profiles with respect to motor performance, long-term memory and skeletal muscular strength were measured, together with total brain antiepileptic drug concentrations. RESULTS TP10 administered intraperitoneally at 10 mg/kg significantly elevated the threshold for electroconvulsions in mice. TP10 at doses of 2.5 and 5 mg/kg had no impact on the threshold for electroconvulsions in mice. Moreover, TP10 (5 mg/kg) significantly enhanced the anticonvulsant activity of valproate, but not that of carbamazepine, phenobarbital or phenytoin in the maximal electroshock seizure test in mice. Pharmacokinetic experiments revealed that TP10 significantly elevated total brain concentrations of valproate in mice. CONCLUSIONS The enhanced anticonvulsant action of valproate by TP10 in the mouse maximal electroshock-induced seizure model was associated with a pharmacokinetic increase in total brain valproate concentrations in mice. The combinations of TP10 with carbamazepine, phenobarbital and phenytoin were neutral from a preclinical viewpoint.

Microbiologically active Mannich bases derived from 1,2,4-triazoles. The effect of C-5 substituent on antibacterial activity

Our research proved that chemical character of the C-5 substituent significantly determines the antibacterial activity of the Mannich bases derived from 4,5-disubstituted 1,2,4-triazole-3-thiones. This activity was considerably increased by an introduction of a chlorine atom to the phenyl ring. The obtained compounds were particularly active against opportunistic bacteria (Bacillus subtilis and Bacilluscereus). The antibacterial activity of some Mannich bases was similar or higher than the activity of commonly used antibiotics such as ampicillin and cefuroxime.