A novel 1-benzoazepine-derived Michael acceptor and its hetero-adducts active against MRSA

Multidrug-resistant bacterial infections continue to be a rising global health concern. Herein, we describe the development of a novel class of 3-substituted benzoazepinedione derivatives with promising antibacterial activity. The pivotal compound, benzoazepinedione carboxylate 9, represents a highly electrophilic Michael acceptor, enabling divergent access to a wide range of thia-, aza-, oxa-, and phospha-Michael adducts. Notably, most prepared compounds exhibited potent antibacterial activity against both drug-susceptible and drug-resistant strains of Staphylococcus aureus (MIC90 of up to 2 μg mL-1). The cytotoxicity assessment in the VERO6 cell line revealed that thia-adduct 10d (IC50 of 36.5 μg mL-1) exhibits lower toxicity compared to its parent electrophile 9 (IC50 of 14.3 μg mL-1), which is in agreement with the hypothesis of covalently modified prodrugs. Additionally, stability studies of the prepared compounds in CD3OD and a DMSO-PBS mixture confirmed that thia-Michael adducts 10 are stable under neutral conditions while dynamic under mildly basic conditions. Moreover, 3D reconstructed tissue models (human lung epithelial EpiAirway™ and a human small intestine model) did not exhibit a viability decrease below 80% of the untreated control at all concentrations tested, indicating tolerance to higher concentrations of potential drugs and prodrugs.

Synthesis, Spectroscopic Studies and Keto-Enol Tautomerism of Novel 1,3,4-Thiadiazole Derivative Containing 3-Mercaptobutan-2-one and Quinazolin-4-one Moieties

In this study, a novel 1,3,4-thiadiazole derivative containing 3-mercaptobutan-2-one and quinazolin-4-one moieties (Compound 3) is synthesized by the coupling of 2-amino-1,3,4-thiadiazole-5-(3-mercaptobutan-2-one) (Compound 1) with 2-Phenyl-4H-3,1-benzoxazin-4-one (Compound 2) in one molecule moiety. Compound 3 is found to exist as two types of intra-molecular hydrogen bonding with keto-enol tautomerism characters, which is further confirmed using FTIR, ¹H-NMR, ¹³C-NMR, mass spectrometer, and UV-Visible spectra. The ¹H-NMR and UV-Visible spectra of Compound 3 are investigated in different solvents such as methanol, chloroform, and DMSO. Compound 3 exhibits keto-enol tautomeric forms in solvents with different percentage ratios depending on the solvent polarity. The ¹H-NMR and UV-Visible spectral results show that Compound 3 favors the keto over the enol form in polar aprotic solvents such as DMSO and the enol over the keto form in non-polar solvents such as chloroform. The ¹³C-NMR spectrum gives two singles at δ 204.5 ppm, due to ketonic carbon, and δ 155.5 ppm, due to enolic carbon, confirming the keto-enol tautomerism of Compound 3. Furthermore, the molecular ion at m/z 43 and m/z 407 in the mass spectrum of Compound 3 and fragmentation mechanisms proposed reveal the existence of the keto and enol forms, respectively.

2-Acetyl-1,3-cyclopentanedione–oxovanadium(IV) complexes. Acidity and implications for gastrointestinal absorption

Since vanadyl sulphate has demonstrated insulin-like effects on glucose metabolism in animal and human trials, and organic vanadium complexes are better absorbed by the intestinal tract than vanadyl species, in this work the complexation of oxovanadium(IV) with 2-acetyl-1,3-cyclopentanedione is studied. Kinetic and equilibria in aqueous 1:1 chelation are investigated spectrophotometrically in aqueous solution at 25 degrees C. The mechanism proposed to account for the kinetic data involves a reversible pathway where VO(+2) reacts with the enolate ion of the ligand. From calculated kinetic and thermodynamic parameters, it can be expected that the rates between final and initial monocharged complex concentration could help a better control of the absorption through the lipophilic membranes in the intestinal tract.