Barbara Kaproń

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.

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.

Studies on the Anticonvulsant Activity and Influence on GABA-ergic Neurotransmission of 1,2,4-Triazole-3-thione- Based Compounds

The anticonvulsant activity of several 1,2,4-triazole-3-thione derivatives on mouse maximal electroshock-induced seizures was tested in this study. Characteristic features of all active compounds were rapid onset of action and long lasting effect. Structure-activity observations showed that the probability of obtaining compounds exerting anticonvulsant activity was much higher when at least one of the phenyl rings attached to 1,2,4-triazole nucleus had a substituent at the para position. The obtained results, moreover, permit us to conclude that despite the structural similarity of loreclezole (second-generation anticonvulsant drug) and the titled compounds, their anticonvulsant activity is achieved via completely different molecular mechanisms.

Structure–activity Relationship Studies of Microbiologically Active Thiosemicarbazides Derived from Hydroxybenzoic Acid Hydrazides

Forty‐five derivatives of thiosemicarbazide were synthesized, and their antibacterial activity against Gram‐positive and Gram‐negative bacteria was evaluated. Some of the described compounds exhibited interesting activity against reference strains of Gram‐positive bacteria, whereas only two derivatives had the ability to inhibit the growth of Gram‐negative species (Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 13883, Proteus mirabilis ATCC 12453). The most potent antimicrobial activity was observed in the cases of salicylic acid hydrazide derivatives. The differences in activity inspired us to conduct conformational analysis using molecular mechanics level. The obtained results suggest that the molecule geometry, especially at the N4–terminus of thiosemicarbazide skeleton, determines the antibacterial activity. Unfortunately, in opposition to what we expected, only one of the tested compounds inhibited the activity of the topoIV enzyme, and none of them was active against DNA gyrase.

Design, synthesis and biological evaluation of 4-benzoyl-1-dichlorobenzoylthiosemicarbazides as potent Gram-positive antibacterial agents

Abstract Twelve 4-benzoyl-1-dichlorobenzoylthiosemicarbazides have been tested as potential antibacterials. All the compounds had MICs between 0.49 and 15.63 µg/ml toward Micrococcus luteus, Bacillus cereus, Bacillus subtilis and Staphylococcus epidermidis indicating, in most cases, equipotent or even more effective action than cefuroxime. In order to clarify if the observed antibacterial effects are universal, further research were undertaken to test inhibitory potency of two most potent compounds 3 and 11 on clinical isolates of Staphylococcus aureus. Compound 11 inhibited the growth of methicillin-sensitive S. aureus (MSSA) at MICs of 1.95–7.81 µg/ml, methicillin-resistant S. aureus (MRSA) at MICs of 0.49–1.95 µg/ml and MDR–MRSA at MIC of 0.98 and 3.90 µg/ml, respectively. Finally, inhibitory efficacy of 3 and 11 on planktonic cells and biofilms formation in clinical isolates of S. aureus and Haemophilus parainfluenzae was tested. The majority of cells in biofilm populations of MSSA and MRSA were eradicated at low level of 3, with MBICs in the range of 7.82–15.63 µg/ml.

Search for human DNA topoisomerase II poisons in the group of 2,5-disubstituted-1,3,4-thiadiazoles

Abstract A series of six 2,5-disubstituted 1,3,4-thiadiazole derivatives was synthesized and examined for cytotoxic activity in MCF-7 and MDA-MB-231 breast cancer cells. MTT assay confirmed that 2-(3-fluorophenylamino)-5-(3-hydroxyphenyl)-1,3,4-thiadiazole (2), 2-(4-bromophenylamino)-5-(2,4-dichlorophenyl)-1,3,4-thiadiazole (3), 2-(4-fluorophenylamino)-5-(2,4-dichlorophenyl)-1,3,4-thiadiazole (4), had ability to inhibit MCF-7 and MDA-MB-231 cells proliferation. The IC50 values for the mentioned compounds ranged between 120 and 160 μM (with respect to MCF-7 cells) and from 70 to 170 μM (with respect to MDA-MB-231 cells). It turned out, moreover, that compound 2 is a human topoisomerase II (topoII) catalytic inhibitor whereas the two other compounds (i.e. 3 and 4) are capable of stabilizing DNA-topoII cleavage complex and thus are topoII poisons.

Dual Antibacterial and Anticancer Activity of 4-Benzoyl-1-dichlorobenzoylthiosemicarbazide Derivatives

OBJECTIVE/METHOD A group of 4-benzoyl-1-dichlorobenzoylthiosemicarbazides endowed with antibacterial activity was evaluated for its cytotoxic properties against breast cancer cells (MCF-7, MDA-MB-231) and head and neck squamous cell carcinomas (FaDu, SCC-25). Cytotoxicity of the investigated compounds was measured using MTT and [3H]-thymidine incorporation bioassays. RESULT 1-(2,3-Dichlorobenzoyl)-4-(2-methylbenzoyl)thiosemicarbazide (TA-4), 1-(2,4-dichlorobenzoyl)- 4-(2-methylbenzoyl)thiosemicarbazide (TA-18), and 1-(2,4-dichlorobenzoyl)-4-(4-nitrolbenzoyl)- thiosemicarbazide (TA-20) were found to possess anticancer activity equipotent or even stronger than that of reference drug - etoposide. In order to clarify the molecular mode of action of the mentioned compounds, the relaxation assay kit for human DNA topoisomerase II was used. It turned out that reduction of viability of cancer cells was a result of inhibition of human DNA topoII. Molecular docking studies proved that 4-benzoyl-1-dichlorobenzoylthiosemicarbazides strongly interact with DNAdependent subunit of that enzyme.

Molecular mechanism of action and safety of 5-(3-chlorophenyl)-4-hexyl-2,4-dihydro-3H-1,2,4-triazole-3-thione - a novel anticonvulsant drug candidate

Previously, it was found that 5-(3-chlorophenyl)-4-hexyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (TP-315) effectively protects mice from maximal electroshock-induced seizures. The aim of this study was to determine possible interactions between TP-315 and different molecular targets, i.e. GABAA receptors, voltage-gated sodium channels, and human neuronal α7 and α4β2 nicotinic acetylcholine receptors. The influence of TP-315 on the viability of human hepatic HepG2 cells was also established using PrestoBlue and ToxiLight assays. It was found that the anticonvulsant activity of TP-315 results (at least partially) from its influence on voltage-gated sodium channels (VGSCs). Moreover, the title compound slightly affected the viability of human hepatic cells.