A FRET-based random screening assay was used to generate hit compounds as sortase A inhibitors that allowed us to identify ethyl 3-oxo-2-(2-phenylhydrazinylidene)butanoate as an example of a new class of sortase A inhibitors. Other analogues were generated by changing the ethoxycarbonyl function for a carboxy, cyano or amide group, or introducing substituents in the phenyl ring of the ester and acid derivatives. The most active derivative found was 3-oxo-2-(2-(3,4dichlorophenyl)hydrazinylidene)butanoic acid (2b), showing an IC₅₀ value of 50 µM. For a preliminary assessment of their antivirulence properties the new derivatives were tested for their antibiofilm activity. The most active compound resulted 2a, which showed inhibition of about 60% against S. aureus ATCC 29213, S. aureus ATCC 25923, S. aureus ATCC 6538 and S. epidermidis RP62A at a screening concentration of 100 µM.

The endocannabinoid system is implicated in multiple physiological and pathological processes, making it a promising target for therapeutic intervention. CB1 receptor antagonists have shown potential in treating metabolic, neuropsychiatric, and addiction-related disorders. However, the adverse effects of CB1 antagonists like rimonabant have spurred the development of new compounds with improved safety profiles. This study investigates the pharmacological effects of a novel synthetic compound, 3-(5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-1H-pyrazol-3-yl)-2-phenylchinazolin-4(3H)-one (QD13), a quinazolinone derivative designed to antagonize CB1 receptor activity selectively. Molecular docking studies were conducted to assess the binding affinity of QD13 at the CB1 receptor, comparing it to the reference antagonist AM6538. The effects of QD13 were evaluated using the tetrad task in C57Bl/6 mice. The ability of QD13 to antagonize the effects of the CB1 agonist CP55,940 on locomotor activity, body temperature, catalepsy, and nociception were measured. Additionally, isolated ileum preparations were used to determine QD13's impact in counteracting the effects of CB1 agonists on gastrointestinal contractility. Docking analysis confirmed QD13's occupation of the CB1 receptor binding site, overlapping with AM6538, suggesting strong affinity. QD13 dose-dependently reversed CP55,940-induced hypomotility, catalepsy, analgesia, and hypothermia, with significant effects observed at 1 mg/kg and 3 mg/kg. Moreover, QD13 counteracted CP55,940-induced inhibition of ileal contractility, supporting its antagonistic activity in peripheral tissues. QD13 shows promising CB1 receptor antagonistic activity both centrally and peripherally. Its modulation of CB1 effects in the tetrad task and gastrointestinal assays suggests potential therapy for neuropsychiatric disorders, obesity, and addiction. Further studies are needed to clarify QD13's safety and efficacy.

Several new synthesized 4-cinnamamido- and 2-phenoxyacedamido-(1H-pyrazol-5-yl)benzamides were obtained by two multi step different synthetic routes in order to maximize their yield. The new derivatives were screened to determine the antiproliferative, antimicrobial and antibiofilm activity. The biological results showed how, respect to the antiproliferative and antimicrobial activities, the compounds have a low to missing activity. Different are the results obtained concerning the antibiofilm activity, especially towards Candida albicans. Most of the synthesized compounds showed a good percentage inhibition of biofilm formation ranging from 60 to 73% with a Biofilm Inhibition Concentration 50% (BIC₅₀) from 0.13 to 0.01 µM. Among the synthesized compounds the ethyl 5-(4-(2-(4-chlorophenoxy)acetamido)benzamido)-1-methyl-1H-pyrazole-4-carboxylate (27c) resulted the most active molecule with a BIC₅₀ of 0.01 µM. According to the results obtained, such compound could be considered a lead subject of further studies to obtain novel and more effective antibiofilm agents against C. albicans.

Background/Objectives: Biofilm-related infections represent a major concern in clinical practice because of their poor responsiveness to standard antimicrobial treatments. Over the past decade, many efforts have been made to identify new compounds capable of inhibiting this particularly resistant form of bacterial life. Although several compounds have shown interesting anti-biofilm properties, none have reached the clinic. Methods: In the present work, we describe the synthesis and biological assessment as anti-biofilm agents, of a novel library of twenty-one imidazo[2,1-b][1,3,4]thiadiazol-2-yl]-1H-pyrrolo[2,3-b]pyridines. Results: The newly synthesized compounds were in vitro evaluated for their ability to prevent biofilm formation and to eradicate established biofilms in Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 15442. Additionally, the most potent compounds, 9g and 9u, were in vivo assayed for their safety profile and the anti-infective effect in a Galleria mellonella model. Conclusions: Derivatives 9g, 9i, 9n, 9q and 9u proved to be potent inhibitors of S. aureus biofilm showing BIC₅₀ values lower than 15 µg/mL. Noteworthy, the in vivo results revealed the promising protective properties of compound 9u in the early stage of staphylococcal infection.