Antibacterial, antifungal, and anti-biofilm effects of sulfamethoxazole-complexes against pulmonary infection agents.

Antibiotic resistance associated with pulmonary infection agents has become a public health problem, being considered one of the main priorities for immediate resolution. Thus, to increase the therapeutic options in the fight against resistant microorganisms, the synthesis of molecules from pre-existing drugs has shown to be a promising alternative. In this sense, the present work reports the synthesis, characterization, and biological evaluation (against fungal and bacterial agents that cause lung infections) of potential metallodrugs based on sulfamethoxazole complexed with AuI, AgI, HgII, CdII, NiII, and CuII. The minimal inhibitory concentration (MIC) value was used to evaluate the antifungal and antibacterial properties of the compounds. In addition, it was also evaluated the antibiofilm capacity in Pseudomonas aeruginosa, through the quantification of its biomass and visualization using atomic force microscopy. For each case, molecular docking calculations were carried out to suggest the possible biological target of the assayed inorganic complexes. Our results indicated that the novel inorganic complexes are better antibacterial and antifungal than the commercial antibiotic sulfamethoxazole, highlighting the AgI-complex, which was able to inhibit the growth of microorganisms that cause lung diseases with concentrations in the 2-8 µg mL-1 range, probably at targeting dihydropteroate synthetase - a key enzyme involved in the folate synthesis. Furthermore, sulfamethoxazole complexes were able to inhibit the formation of bacterial biofilms at significantly lower concentrations than free sulfamethoxazole, probably mainly targeting the active site of LysR-type transcriptional regulator (PqsR). Overall, the present study reports preliminary results that demonstrate the derivatization of sulfamethoxazole with transition metal cations to obtain potential metallodrugs with applications as antimicrobial and antifungal against pulmonary infections, being an alternative for drug-resistant strains.

Molecular docking, quorum quenching effect, antibiofilm activity and safety profile of silver-complexed sulfonamide on Pseudomonas aeruginosa.

Microbial infections caused by sessile microorganisms are known to be a more challenging issue than infections caused by the same microorganisms in the planktonic state. Pseudomonas aeruginosa is an opportunistic pathogen and biofilm-forming agent. This species presents intense cellular communication mediated by signaling molecules. This process is known as quorum sensing (QS) and induces the transcription of specific genes that favors cell density growth and three-dimensional bacterial grouping. In this context, the discovery of compounds capable of inhibiting the action of the QS signaling molecules seems to be a promising strategy against biofilms. This work aimed to evaluate the anti-biofilm action and the in vitro safety profile of a sulfamethoxazole-Ag complex. The results obtained indicate potential anti-biofilm activity through QS inhibition. In silico tests showed that the compound acts on the las and pqs systems, which are the main regulators of biofilm formation in P. aeruginosa. Additionally, the molecule proved to be safe for human peripheral blood mononuclear cells.

Sulfamethoxazole derivatives complexed with metals: a new alternative against biofilms of rapidly growing mycobacteria.

Biofilms are considered important sources of infections on biomedical surfaces, and most infections involving biofilm formation are associated with medical device implants. Therefore, there is an urgent need for new antimicrobial compounds that can combat microbial resistance associated with biofilm formation. In this context, this work aimed to evaluate the antibiofilm action of sulfamethoxazole complexed with Au, Cd, Cu, Ni and Hg on rapidly growing mycobacteria (RGM), as well as to evaluate their safety through cytotoxic assays. The results demonstrate potentiation of the novel compounds in antibiofilm activity, mainly in the complex with Au, which was able to completely inhibit biofilm formation and had the capacity to destroy the biofilm at all the concentrations tested. All cytotoxic data suggest that the majority of sulfamethoxazole metallic derivatives are antimicrobial alternatives, as well as safe molecules, which could be used as potential therapeutic agents for bacterial and biofilm elimination.

A Vanadium(V) complexes derived from pyridoxal/salicylaldehyde. Interaction with CT-DNA/HSA, and molecular docking assessments.

With the increasing development of metallopharmaceuticals, coordination compounds become viable alternatives for therapeutic uses. Despite the importance of platinum derivatives in this area, first-row transition metals complexes are welcome due to their characteristics. Vanadium is a promising metal in this context, as it has a range of compounds with different biological applications, including anticancer therapeutic effects. In this effort, the study of interactions between coordination compounds with deoxyribonucleic acid and with human serum albumin is fundamental. In this way, ten iminic ligands were synthesized by condensing p-substituted aromatic benzohydrazides (OH, CH3, H, NO2, and NH2) with salicylaldehyde (L1As-L5As) or pyridoxal hydrochloride (L1P-L5P). These ligands have characteristics that allow the tridentate coordination of vanadium cations, leading to the formation of ten vanadium(V) complexes (C1As-C5As and C1P-C5P) with different structural features, all characterized by single-crystal X-ray diffraction, UV-Vis and infrared spectroscopies, and cyclic voltammetry. In addition, the complexes were tested for their interactions with calf thymus deoxyribonucleic acid and human serum albumin by spectroscopic assays and molecular docking calculations. These new results can contribute to further research and provide different ways to design new vanadium complexes with biological applications.

Pyridoxal water-soluble cobalt(II) helicates: Synthesis, structural analysis, and interactions with biomacromolecules.

Helical complexes composed of organic ligand strands and metallic centers, called helicates, present interactions with biomacromolecules, such as deoxyribonucleic acid, as one of their main biological applications in bioinorganic chemistry. Despite the potential antineoplastic and antibacterial results of the interactions between helicates and biomacromolecules, there is still a gap of research in the literature, primarily in terms of solubility in aqueous media. In this study, we present the synthesis, structural analysis, and interaction with biomacromolecules of two water-soluble cobalt(II) double-stranded helicates: [CoII2L22][CoII(NCS)4]∙9H2O (C1) and [CoII2L42]Cl2∙11H2O (C2). These complexes are obtained from iminic ligands (L2 and L4) derived from pyridoxal, a vitamin B6 aldehyde derivative. Through spectroscopic assays, these helical complexes were shown to have weak and moderate binding capacities with calf-thymus deoxyribonucleic acid and human serum albumin, respectively. The theoretical assays suggest that C1 and C2 interact with the minor groove of deoxyribonucleic acid and have different main binding sites with human serum albumin. Furthermore, Van der Waals and hydrogen bonds were shown to be the main intermolecular forces for these C1-C2:biomacromolecules interactions.

Sulfonamides complexed with metals as mycobacterial biofilms inhibitors.

Rapidly growing mycobacteria (RGM) are found in non-sterile water and often associated with severe post-surgical infections and affect immunocompromised patients. In addition, RGM can prevent the host's immune response and have the ability to adhere to and form biofilms on biological and synthetic substrates, making pharmacological treatment difficult because conventional antimicrobials are ineffective against biofilms. Thus, there is an urgent need for new antimicrobial compounds that can overcome these problems. In this context, sulfonamides complexed with Au, Cd, Ag, Cu, and Hg have shown excellent activity against various microorganisms. Considering the importance of combating RGM-associated infections, this study aimed to evaluate the activity of sulfonamide metal complexes against RGM biofilm. The sulfonamides were tested individually for their ability to inhibit mycobacterial formation and destroy the preformed biofilm of standard RGM strains, such as Mycobacterium abscessus, M. fortuitum, and M. massiliense. All sulfonamides complexed with metals could reduce, at subinhibitory concentrations, the adhesion and biofilm formation of three RGM species in polystyrene tubes. It is plausible that the anti-biofilm capacity of the compounds is due to the inhibition of c-di-GMP synthesis, which is an important signal for RGM biofilm formation. Hence, the impacts and scientific contribution of this study are based on the discovery of a potential new therapeutic option against RGM-associated biofilm infections. Sulfonamides complexed with metals have proven to be a useful and promising tool to reduce microbial adhesion on inert surfaces, stimulating the improvement of methodologies to insert compounds as new antibacterial and coating agents for medical and hospital materials.

SOD activity of new copper II complexes with ligands derived from pyridoxal and toxicity in Caenorhabditis elegans.

This work presents the synthesis, characterization of copper(II) complexes (C1-C6) and the potential of these compounds to mimic the catalytic activity of the enzyme superoxide dismutase (SOD). The copper(II)complexes were obtained by reaction between the aldol condensation between substituted aromatic hydrazides and aromatic aldehydes (salicylic aldehyde and pyridoxal hydrochloride), forming two new ligands (L1 to L6), resulting in new dimeric dicopper (II) complexes (C1 and C2), new three monomeric CuII derivatives (C3, C4 and C6) and a polymeric complex (C5). The CuII complexes were fully characterized by X-ray diffraction, spectroscopic and electrochemical analysis. Subsequently, CuII derivatives were evaluated for their antioxidant activities, using the NBT (Nitro blue tetrazolium chloride) photoreduction methodology. After evaluating the antioxidant activity in vitro, it was observed that the best inhibition rates of the superoxide ion are associated to the C4 and C5 complexes. Computational analysis via molecular docking and quantum chemical calculation (Fukui map) offered a molecular level explanation on the biological activity of CuII complexes. Additionally, cytotoxicity of C1-C6 was tested in the first time in vivo in nematodes Caenorhabditis elegans, corroborating with the results identified for C4 and C5.