Synthesis, identification and antimicrobial activity of substituted thiazolines and 1,3,4-thiadiazines from dehydroacetic acid

Evaluating Efflux Pump Inhibition in Staphylococcus aureus 1199B Strain Using Thiadiazine-Derived Compounds: In Vitro and In Silico Approaches

Thiadiazines are heterocyclic compounds known for some pharmacological activities. However, the ability of these compounds and their derivatives to act as antibacterial agents and inhibitors of the efflux system in resistant bacteria remains unknown. This study aims to evaluate the antibacterial and NorA efflux pump inhibitory activities of thiadiazine-derived compounds (IJ14, IJ15, IJ16, IJ17, IJ18, IJ19, and IJ20) against the Staphylococcus aureus 1199B strain. Minimum Inhibitory Concentration (MIC) tests and antibacterial activity assessment through NorA efflux system inhibition were performed using microdilution assays in 96-well plates. Additionally, ethidium bromide (EtBr) fluorescence emission assays were conducted to evaluate efflux system inhibition. The methodology revealed that the IJ17 and IJ20 compounds presented MIC values of 256 and 597.3 μg/mL, respectively. The efflux pump inhibition assessment using the microdilution method showed significant results for all compounds, which also increased the fluorescence rates emitted by EtBr. Consequently, thiadiazine-derived compounds exhibit promising results in targeting a key bacterial resistance mechanism, underscoring the need for further studies, such as molecular tests, to evaluate their mechanism of action and clarify the feasibility and efficacy of these compounds as antibacterial agents.

Thiazine-derived compounds in inhibiting efflux pump in Staphylococcus aureus K2068, mepA gene expression, and membrane permeability alteration

Staphylococcus aureus is a bacterium responsible for resistance to multiple drugs and the efflux system is widely studied among the resistance mechanisms developed by this species. The present study evaluates the inhibition of the MepA efflux pump by thiadiazine-derived compounds. For this purpose, thiadiazine-derived compounds (IJ-14 to IJ-20) were tested against S. aureus K2068 strains. Microdilution tests were initially conducted to assess the Minimum Inhibitory Concentration (MIC) of the compounds and their efflux pump inhibition activity. In addition, fluorimetry tests were performed using BrEt emission and tests were conducted to inhibit the expression of the mepA gene. This involved comparing the bacterial gene expression with the antibiotic alone to the gene expression after combining compounds (IJ-17 and IJ-20) with the antibiotic. Furthermore, membrane permeability assessment tests and in silico molecular docking tests were performed. It was observed that the IJ17 and IJ20 compounds exhibited direct activity against the tested strain. The IJ17 compound produced significant results in the gene inhibition tests, which was also evidenced through the membrane permeability alteration test. These findings suggest that thiadiazine-derived compounds have promising effects against one of the main resistance mechanisms, with the IJ17 compound presenting observable mechanisms of action.

Dehydroacetic acid a privileged medicinal scaffold: A concise review

From the last decade, research on dehydroacetic acid (DHA) and its derivatives has increased immensely due to its significant role in various fields, including medicine, cosmetics, food industry, and so on. In the medicinal area, DHA plays an essential role in developing novel action-based drugs, which are helpful for treating various diseases. Besides its plethora of biological applications, its chelating ability offers the easiest synthetic route for synthesizing more active metal complexes. DHA derivatives along with their metal complexes show a number of biological activities and also exhibit various interactions with multiple biological targets. This article summarizes recent medicinal applications (2000-onwards) of DHA-based compounds and their analogs, along with their structure-activity relationship (SAR) analysis. Their interactions with different target enzymes are also discussed. This information derived from SAR analysis would be helpful for medicinal chemists working on the development of drugs based on heterocyclic frameworks, particularly those based on the DHA scaffold.

Potentiating-antibiotic activity and absorption, distribution, metabolism, excretion and toxicity properties (ADMET) analysis of synthetic thiadiazines against multi-drug resistant (MDR) strains

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.

Serological Cross-Reaction between Six Thiadiazine by Indirect ELISA Test and Their Antimicrobial Activity

Malaria is a parasitic infection caused by a protozoon of the genus Plasmodium, transmitted to humans by female biting mosquitoes of the genus Anopheles. Chloroquine and its derivates have caused the parasite to develop drug resistance in endemic areas. For this reason, new anti-malarial drugs as treatments are crucial. This work aimed to evaluate the humoral response. with hyper-immune sera, of mice immunized with six derivatives of tetrahydro-(2H)-1,3,5-thiadiazine-2-thione (bis-THTT) by indirect ELISA test. The cross-reactivity between the compounds as antigens and their microbial activity on Gram-positive and Gram-negative bacteria was evaluated. The results of the humoral evaluation by indirect ELISA show that three bis-THTTs react with almost all of the above. Besides, three compounds used as antigens stimulate the BALB/c mice’s immune system. The best combination of two antigens as a combined therapy displays similar absorbances between the antigens in the mixture, showing similar recognition by antibodies and their compounds. In addition, our results showed that different bis-THTT presented antimicrobial activity on Gram-positive bacteria, mainly on Staphylococcus aureus strains, and no inhibitory activity was observed on the Gram-negative bacteria tested.