Federica Belluti

FAD/NAD(P)H‐dependent dehydrogenases form a structurally conserved family of redox enzymes that participate in essential metabolic processes across parasites and higher organisms. Among them, trypanothione reductase (TR) is a key component of the redox metabolism of Leishmania species and represents an attractive target for antileishmanial drug development. However, because several flavoproteins share similar folds and cofactor‐binding architectures, the selectivity of TR inhibitors remains a critical issue during early drug discovery. To explore this aspect, we investigated the structural landscape of FAD/NAD(P)H‐dependent dehydrogenases in Leishmania infantum by integrating sequence analysis, structural modeling, docking simulations, and in vitro biochemical validation. Reciprocal sequence searches revealed 11 parasite flavoproteins structurally related to TR, including a dihydrolipoamide dehydrogenase (DLD)‐like protein, a type II NADH dehydrogenase (NDH2)‐like protein, and a dienoyl‐CoA reductase (deCoAR)‐like protein. Comparative docking analyses across parasite and mammalian homologs allowed us to examine potential cross‐reactivity patterns among these enzymes. Enzymatic assays performed on recombinant L. infantum TR (LiTR) and Caldalkalibacillus thermarum NDH2 (CtNDH2) confirmed that selected ligands can exert enzyme‐dependent effects. In particular, auranofin and, to a lesser extent, nitrofurazone inhibited LiTR, whereas a terpyridine–Pt‐derived compound strongly inhibited LiTR while stimulating CtNDH2 activity. Overall, the results illustrate how structurally related flavoproteins may accommodate common ligands while responding with distinct catalytic outcomes. The integrated computational and biochemical workflow presented here provides a practical framework for assessing ligand selectivity within the FAD/NAD(P)H‐dependent dehydrogenase family and may support the development of selective modulators targeting parasite redox metabolism.

Naturally inspired electrophilic scaffolds, such as chalcone, curcumin, aurone, C-5-monocarbonyl-curcumin, and bis-(arylidene)piperidone, are considered privileged structures because of their ability to interact with a variety of biological macromolecules, including receptors and enzymes. They thus serve as versatile platforms for drug discovery efforts aimed at developing structurally related analogues endowed with improved bioactivity. Five-membered nitrogen-based heterocycles, such as triazole and pyrazole, have been widely used in medicinal chemistry both as templates and spacers for the design of bioactive compounds; they indeed provide the advantage of enhancing favourable interactions with the target, while also improving solubility and bioavailability, along with reducing toxicity. This review reports the latest advances in the development of hybrids incorporating the above classes of synthons acting as potential anticancer chemotherapeutics and provides a critical summary of the design strategies that have guided the development of antitumor agents.

Natural products (NPs) have historically been regarded as the most important sources of bioactive compounds

Background/Objectives: Malaria remains the most critical parasitic disease globally, responsible for over 600.000 deaths annually. In sub-Saharan Africa, co-infections of Plasmodium falciparum with other pathogens, particularly Staphylococcus aureus, are common in children with severe malaria. Therefore, the design of new compounds targeting both pathogens appears to be an urgent priority. Methods: A small series of hybrid compounds was designed and synthesized by linking the pharmacophore of the antimalarial drug chloroquine with the phenothiazine core. These compounds were tested in vitro against a panel of microbial strains and further analyzed through in silico simulations to predict their physical-chemical properties. Results: Compounds 4b and 5b emerged the most potent candidates of the series, showing a sub-micromolar inhibitory activity on P. falciparum, and a promising micromolar potency on S. aureus alongside with a low toxicity on mammalian cells. Molecular docking followed by molecular dynamics (MD) simulations identified the respiratory membrane NDH-2 enzyme as common target in both pathogens. Conclusions: Both experimental and computational findings provide compelling evidence for the use of the designed compounds in a STOP strategy, i.e., Same-Target-Other-Pathogen, to treat malaria and bacterial infections concurrently.

Oxidative stress, driven by excess reactive oxygen species (ROS), is a key factor in the progression of neurodegenerative diseases like Alzheimer’s disease (AD). In this context, copper dysregulation can also contribute to this imbalance, being responsible for enhanced ROS production, so that copper scavenging has been investigated as a possible therapeutic strategy. This study investigates the behavior of two isostructural ligands, featuring an N₃O donor set, that effectively chelate Cu(II) in aqueous solution. Interestingly, their resulting mono- or dinuclear copper complexes feature a coordination environment suitable to foster antioxidant activity. By transforming copper’s oxidant potential into antioxidant action, these systems may reduce copper-induced oxidative damage. The work examines the pH-dependent metal-binding behavior of the ligands, the catalytic properties of the resulting complexes under physiological conditions, and their ability to inhibit β-amyloid peptide aggregation.

Fungal infections are recognized as a global health issue, in particular considering the spread of different forms of resistance to the commonly used antifungal drugs and their involvement in the occurrence of co-infections in hospitalized and immunocompromised patients. In this paper, a small series of hybrid compounds were designed and synthesized by linking the privileged chromone and xanthone scaffolds, endowed with recognized antimicrobial potential, to the tert-butylbenzylamino portion of the antifungal drug butenafine, through selected linkers. The results showed for the xanthone-based compound 3 a promising activity towards C. auris, C. tropicalis, and C. neoformans, for which a high degree of resistance is commonly observed, together with a significant antibacterial potency towards Gram-positive bacteria, such as S. aureus. Considering that compound 3 displayed favorable selectivity and therapeutic indexes (9.1 and >16, respectively), it appeared as a valuable prototype, deserving further hit-to-lead optimization.

Aiming at developing a new class of quaternary pyridinium salts, the lead compound 1, characterized by a pyridine‐3‐yl chalcone framework, was rationally modified by inserting alkyl functions varying from 6 to 18 carbon units. Among the set, some valuable lead compounds were identified. Derivatives 4–6 were primarily active against Staphylococcus aureus and Candida albicans, respectively (MIC = 1.56 and 3.125 μM). In comparison, analogs 4 and 5 showed significant activities against Escherichia coli (MIC = 6.25 μM). Interestingly, the antimicrobial property of compounds 4–6, as well as their antibiofilm activity, occurred at lower concentrations than their cyto‐ and erythrocyte toxicities, thus ensuring a favorable safety profile. Structure–activity relationship analysis highlighted the critical role of the alkyl tail length in the antimicrobial activity, and optimal results were observed for moieties ranging from 10 to 14 carbon units. Molecular dynamics studies performed on 2 and 5 by modeling them on Gram‐positive and Gram‐negative membranes showed that the derivatives, upon diffusing across periodic boundary conditions, were able to intercalate into the microbial membranes. The difference in diffusion rates provides useful information to support the diverse antimicrobial potencies of the newly designed quaternary pyridinium salt.