Antimicrobial resistance poses a major threat to global health as the number of efficient antimicrobials decreases and the number of resistant pathogens rises. Our research group has been actively involved in the design of novel antimicrobial drugs. The blueprints of these compounds were azolic heterocycles, particularly thiazole. Starting with oxadiazolines, our research group explored, one by one, the other five-membered heterocycles, developing more or less potent compounds. An overview of this research activity conducted by our research group allowed us to observe an evolution in the methodology used (from inhibition zone diameters to minimal inhibitory concentrations and antibiofilm potential determination) correlated with the design of azole compounds based on results obtained from molecular modeling. The purpose of this review is to present the development of in-house azole compounds with antimicrobial activity, designed over the years by this research group from the departments of Pharmaceutical and Therapeutical Chemistry in Cluj-Napoca.

Considering the important damage caused by the reactive oxygen (ROS) and nitrogen (RNS) species in the human organism, the need for new therapeutic agents, with superior efficacy to the known natural and synthetic antioxidants, is crucial. Quinazolin-4-ones are known for their wide range of biological activities, and phenolic compounds display an important antioxidant effect. Linking the two active pharmacophores may lead to an increase of the antioxidant activity. Therefore, we synthesized four series of new hybrid molecules bearing the quinazolin-4-one and phenol scaffolds. Their antioxidant potential was evaluated in vitro, considering different possible mechanisms of action: hydrogen atom transfer, ability to donate electrons and metal ions chelation. Theoretical quantum and thermodynamical calculations were also performed. Some compounds, especially the ortho diphenolic ones, exerted a stronger antioxidant effect than ascorbic acid and Trolox.

Two series, “a” and “b”, each consisting of nine chemical compounds, with 2,3-disubstituted quinazolin-4(3H)-one scaffold, were synthesized and evaluated for their anticonvulsant activity. They were investigated as dual potential positive allosteric modulators of the GABA_A receptor at the benzodiazepine binding site and inhibitors of carbonic anhydrase II. Quinazolin-4(3H)-one derivatives were evaluated in vivo (D_1–3 = 50, 100, 150 mg/kg, administered intraperitoneally) using the pentylenetetrazole (PTZ)-induced seizure model in mice, with phenobarbital and diazepam, as reference anticonvulsant agents. The in silico studies suggested the compounds act as anticonvulsants by binding on the allosteric site of GABA_A receptor and not by inhibiting the carbonic anhydrase II, because the ligands-carbonic anhydrase II predicted complexes were unstable in the molecular dynamics simulations. The mechanism targeting GABA_A receptor was confirmed through the in vivo flumazenil antagonism assay. The pentylenetetrazole experimental anticonvulsant model indicated that the tested compounds, 1a–9a and 1b–9b, present a potential anticonvulsant activity. The evaluation, considering the percentage of protection against PTZ, latency until the onset of the first seizure, and reduction in the number of seizures, revealed more favorable results for the “b” series, particularly for compound 8b.

The development of hybrid molecules with significant human therapeutic properties is one of the main approaches of pharmaceutical research. One of the most important pharmacophores is the quinazolin-4(3H)-one heterocycle moiety, due to its wide range of biological activities. By its derivatization with polyphenolic compounds, in our previous research, it proved to possess a good antiradical activity of ortho-diphenolic derivatives of quinazolin-4(3H)-one. In this study, we developed two new series of compounds, with an additional phenolic group or with a methyl group on the thioacetohydrazone fragment. The methods used to evaluate the activity of the compounds were radical scavenging, reduction of oxidizing reagents and transition metals’ ions chelation assays. Quantum descriptors were also calculated in order to evaluate the influence of substituents and their position on the activity of the compounds. The cytotoxic activity was evaluated using normal human foreskin fibroblast cells (BJ) and two cancerous cell lines, lung adenocarcinoma cells (A549) and prostate carcinoma cells (LNCaP). The results obtained for the pyrogallol derivatives showed a high antioxidant activity compared to ascorbic acid and Trolox. All the synthesized compounds displayed a higher cytotoxicity against the cancerous cell types and a high cytocompatibility with the normal cells. The antioxidant activity was deeply influenced by the addition of the third phenolic group in the synthesized molecules.

Retinal degenerative processes such as age-related macular degeneration are at the center of many ongoing research studies, as their impact on the general population is significant, with severe visual impairment and even irreversible vision loss if left untreated. Currently, there are few efficient treatments available to stop or limit its progression. In the present paper, a molecular hybridization approach was employed to develop novel compounds that address this issue. By adding either 2-butenal or a β-ionone-derived residue to the hydrazone-catechol-thiazole scaffold, two compounds were designed and synthesized: 5a and 5b. After being characterized by mass spectrometry and nuclear magnetic resonance, and proving potent antioxidant activity in the in vitro assays, the cytotoxicity evaluation using the ARPE-19, BJ, and A549 cell lines revealed a surprisingly low-dose effect of 5a and the unexpected cytotoxic activity of 5b, despite its β-ionone moiety, known for its significant therapeutic properties.

Three new 2,3-disubstituted quinazolin-4(3H)-one derivatives (5a–c) were synthesized by the nucleophilic S-alkylation of 2-mercaptoquinazolin-4(3H)-one derivatives (3a–c) with 5-(2-bromoacetyl)-2-hydroxybenzamide (4) in alkaline conditions. The final compounds were characterized by recording the IR, MS, ¹H-NMR, and ¹³C-NMR spectra. The new synthesized compounds 5a–c were evaluated in vitro for their cytotoxic activity using one normal cell line, human foreskin fibroblasts (BJ), and one cancerous cell line, derived from human hepatocellular carcinoma (HepG2). Sorafenib was used as a reference. The obtained results from the in vitro examination suggested that compound 5a had lower cytotoxic effects on the BJ cells than the positive standard, and compound 5b exhibited the strongest cytotoxic potential against the HepG2 cell line, being less effective compared to sorafenib. In order to evaluate their pharmacological profiles, the compounds were assessed in vitro and in silico by lipophilicity studies, targeted VEGFR-2 molecular docking, molecular dynamics, and MM-PBSA studies. Additionally, the electronic properties were evaluated by an in silico study of the HOMO and LUMO parameters. Compound 5b exhibited the most interesting pharmacological profile in comparison with the other compounds due to its bulkier substituent from position 3 of the quinazolinone core.