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Background: Thiadiazines are heterocyclic compounds that contain two nitrogen atoms and one sulfur atom in their structure. These synthetic molecules have several relevant pharmacological activities, such as antifungal, antibacterial, and antiparasitic. Objectives: The present study aimed to evaluate the possible in vitro and in silico interactions of compounds derived from thiadiazines. Methods: The compounds were initially synthesized, purified, and confirmed through HPLC methodology. Multi‐drug resistant bacterial strains of Staphylococcus aureus 10 and Pseudomonas aeruginosa 24 were used to evaluate the direct and modifying antibiotic activity of thiadiazine derivatives. ADMET assays (absorption, distribution, metabolism, excretion, and toxicity) were conducted, which evaluated the influence of the compounds against thousands of macromolecules considered as bioactive targets. Results: There were modifications in the chemical synthesis in carbon 4 or 3 in one of the aromatic rings of the structure where different ions were added, ensuring a variability of products. It was possible to observe results that indicate the possibility of these compounds acting through the cyclooxygenase 2 mechanism, which, in addition to being involved in inflammatory responses, also acts by helping sodium reabsorption. The amine group present in thiadiazine analogs confers hydrophilic characteristics to the substances, but this primary characteristic has been altered due to alterations and insertions of other ligands. The characteristics of the analogs generally allow easy intestinal absorption, reduce possible hepatic toxic effects, and enable possible neurological and anti‐inflammatory action. The antibacterial activity tests showed a slight direct action, mainly of the IJ23 analog. Some compounds were able to modify the action of the antibiotics gentamicin and norfloxacin against multi‐drug resistant strains, indicating a possible synergistic action. Conclusions: Among all the results obtained in the study, the relevance of thiadiazine analogs as possible coadjuvant drugs in the antibacterial, anti‐inflammatory, and neurological action with low toxicity is clear. Need for further studies to verify these effects in living organisms is not ruled out. [ABSTRACT FROM AUTHOR]

In this study, we synthesized eight new compounds containing the 2‐amino‐cycloalkyl[b]thiophene and acridine moieties (ACT01 and ACS01‐ACS07). None tested compounds presented human erythrocyte cytotoxicity. The new compounds presented antipromastigote activity, where ACS01 and ACS02 derivatives presented significant antileishmanial activity, with better performance than the reference drugs (tri and pentavalent antimonials), with respective IC50 values of 9.60 ± 3.19 and 10.95 ± 3.96 μ m. Additionally, these two derivatives were effective against antimony‐resistant Leishmania (Leishmania) amazonensis strains. In addition, binding and fragmentation DNA assays were performed. It was observed that the antileishmanial activity of ACS01 is not associated with DNA fragmentation of the promastigote forms. However, it interacted with DNA with a binding constant of 104  m−1. In partial least‐squares studies, it was observed that the most active compounds (ACS01 and ACS02) showed lower values of amphiphilic moment descriptor, but there was a correlation between the lipophilicity of the molecules and antileishmanial activity. Furthermore, the docking molecular studies showed interactions between thiophene–acridine derivatives and the active site of pyruvate kinase enzyme with the major contribution of asparagine 152 residue for the interaction with thiophene moiety. Thus, the results suggested that the new thiophene–acridine derivatives are promising molecules as potential drug candidates. [ABSTRACT FROM AUTHOR]

Cancer is a major public health problem with limited success of available treatments, pointing to the need for new strategies to be developed. Phosphoethanolamine exhibits broad antitumor activity in a variety of tumor cells and potent inhibitor effects on tumor progress in vivo. Once-used organophosphates inhibit acetylcholinesterase (AChE), resulting in toxic effects to the user. As this group is present in phosphoethanolamine, we perform prediction of the in silico metabolism of phosphoethanolamine and submit this series to a docking study on AChE. A total of 10 metabolites were indicated by the prediction, including ammonia and hydroxylamine, which were not included in the study. Using a group of 8 organophosphorus whose pIC50 values ranged from 5.92 to 9.47 as template, we observed that no compound present in the phosphoethanolamine series had a binding energy lower than that of organophosphorus, suggesting that the series has low inhibitory power on AChE. In light of this, we conclude that phosphoethanolamine and its predicted metabolites do not significantly inhibit AChE to cause a cholinergic crisis. This finding highlights the importance of investigating this compound as lead for potential anticancer agents. [ABSTRACT FROM AUTHOR]

Semisynthetic and commercial coumarins were investigated for their antibacterial and adjuvant properties with antibiotic agents against norfloxacin, erythromycin, and tetracycline resistant Staphylococcus aureus as based on efflux mechanisms. The coumarins and certain commercial antibiotics had their Minimum Inhibitory Concentrations determined by broth microdilution assay against resistant S. aureus strains which overexpress efflux pump proteins. For evaluation of the modulatory activity, the antibiotics MICs were determined in the presence of the coumarin derivatives at subinhibitory concentration. Although the coumarins did not display relevant antibacterial activity (MIC ≥ 128 µg/mL), they did modulate the antibiotics activities. Various coumarins, especially the alkylated derivatives in combination with antibiotics at subinhibitory concentrations, modulated antibiotic activity, reducing the MIC for tetracycline and norfloxacin by 2 to 8 times. Polar Surface Area (PSA) studies were performed and the fact that the presence of apolar groups is an important factor for the modulatory activity of coumarins was corroborated. Docking on the Penicillin-Binding Protein from MRSA identified that 18 is a potential ligand presenting low Ebinding. The results indicate that coumarin derivatives modulated antibiotic resistance and may be used as potential antibiotic adjuvants, acting by bacterial efflux pump inhibition in S. aureus. [ABSTRACT FROM AUTHOR]