Objective Sulfanilamide,sulfadiazine,and dapsone were the first sulfonamides to be used to treat malaria by disrupting the folate biosynthesis process,which is essential for parasite survival.Therefore,we aimed to synthesize novel N-(2-arylaminophenyl)-2,3-diphenylquinoxaline-6-sulfonamide derivatives through a rational drug design approach.Methods All compounds were synthesized by the conventional method,and the products were characterized by spectral analysis(1 H NMR and mass spectrometry).The progression of the reaction was monitored using thin-layer chromatography(TLC).All the derivatives were analyzed for their effective binding mode in the allosteric site of the plasmodium cysteine protease falcipain-2.Antibacterial and antifungal activities were determined using the broth dilution method.Results S6(N-(2-thiazol-4 yl)-acetyl-aminophenyl)-2,3-diphenylquinoxaline-6-sulfonamide and S9(N-(1 H-benzo[d]imidazol-2-yl)aminophenyl)-2,3-diphenylquinoxaline-6-sulfonamide formed five hydrogen bonds;S8(N-(2-1 H-imidazol-2 yl)aminophenyl)-2,3-diphenylquinoxaline-6-sulfonamide and S10(N-(1 H-benzo[d]imidazol-5-yl)aminophenyl)-2,3-diphenylquinoxaline-6-sulfonamide formed four hydrogen bonds with the allosteric site of the enzyme.Considering the docking scores and formation of hydrogen bonds with the target enzyme,the novel derivatives were processed for wet lab synthesis.All the newly synthesized derivatives were subjected to in vitro antimalarial,antifungal,and antibacterial activities.All the derivatives exhibited sufficient sensitivity to the Plasmodium falciparum strain compared to the standards.Moreover,compounds S9 and S10 showed the most potent dual antimicrobial and antimalarial activities.They also exhibited powerful molecular interactions in molecular docking studies.Conclusion Based on the above results,it was concluded that N-(2-arylaminophenyl)-2,3-diphenylquinoxaline-6-sulfonamide derivatives have excellent biological potential to act as antimalarial,antifungal,and antibacterial agents.
G protein-coupled receptors(GPCRs)convert extracellular stimuli in the form of hormones,odorants and light into profound changes in cell homeostasis.Their timely desensitization is critical for cells to rapidly respond to changes in their environment and to avoid damage from sustained signaling.Seven GPCR kinases(GRKs)phosphorylate and regulate the activity of most of the^800 GPCRs in the human genome.Although GRKs normally play an adaptive role,in conditions such as chronic heart failure they are overexpressed and linked to disease progression.GRK2 and GRK5 have thus become important targets for the treatment of heart failure and pathological cardiac hypertrophy,respectively.Our lab has determined atomic structures representing all three vertebrate GRK subfamilies,and is now in the midst of a campaign to develop selective inhibitors of these enzymes using structure-based rational design.We have identified the FDA approved drug paroxetine as a selective GRK2 inhibitor,determined the crystal structure of the GRK2·paroxetine complex and,in collaboration with the Koch lab,showed that the drug improves contractility in myocytes and,most impressively,recovery in postmyocardial infarcted mice.Since then,we have identified additional chemical scaffolds that exhibit even higher potency and/or selectivity for GRK5.Using a"hybrid"inhibitor design approach we have generated GRK selective chemical probes that exhibit improved potency and stability and are able to increase inotropy and dampen the hypertrophic response in cardiomyocytes and small animal models.Structural analysis has revealed the molecular basis for selectivity and potency in many of these compounds,allowing for the design of future generations of GRK chemical probes.
John J TESMERHelen V WALDSCHMIDTMarie C CATORenee BOULEYOsvaldo CRUZ-RODRIGUEZScott D LARSEN
