Synthesis, biological activities, and evaluation molecular docking-dynamics studies of new phenylisoxazole quinoxalin-2-amine hybrids as potential α-amylase and α-glucosidase inhibitors

New phenylisoxazole quinoxalin-2-amine hybrids 5a-i were successfully synthesised with yields of 53-85% and characterised with various spectroscopy methods. The synthesised hybrids underwent in vitro α-amylase and α-glucosidase inhibitory assays, with acarbose as the positive control. Through the biological study, compound 5h exhibits the highest α-amylase inhibitory activity with IC50 = 16.4 ± 0.1 μM while compounds 5a-c, 5e and 5h exhibit great potential as α-glucosidase inhibitors, with 5c being the most potent (IC50 = 15.2 ± 0.3 μM). Among the compounds, 5h exhibits potential as a dual inhibitor for both α-amylase (IC50 = 16.4 ± 0.1 μM) and α-glucosidase (IC50 = 31.6 ± 0.4 μM) enzymes. Through the molecular docking studies, the inhibition potential of the selected compounds is supported. Compound 5h showed important interactions with α-amylase enzyme active sites and exhibited the highest binding energy of -8.9 ± 0.10 kcal mol-1, while compound 5c exhibited the highest binding energy of -9.0 ± 0.20 kcal mol-1 by forming important interactions with the α-glucosidase enzyme active sites. The molecular dynamics study showed that the selected compounds exhibited relative stability when binding with α-amylase and α-glucosidase enzymes. Additionally, compound 5h demonstrated a similar pattern of motion and mechanism of action as the commercially available miglitol.

Expedient synthesis of imino-C-nucleoside fleximers featuring a one-pot procedure to prepare aryl triazoles

Nucleoside analogues such as the antiviral agents galidesivir and ribavirin are of synthetic interest. This work reports a "one-pot" preparation of similar fleximers using a bifunctional copper catalyst that generates the aryl azide in situ, which is captured by a terminal alkyne to effect triazole formation.

Advances of bioorthogonal coupling reactions in drug development

Currently, bioorthogonal coupling reactions have garnered considerable interest due to their high substrate selectivity and less restrictive reaction conditions. During recent decades, bioorthogonal coupling reactions have emerged as powerful tools in drug development. This review describes the current applications of bioorthogonal coupling reactions in compound library building mediated by the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction and in situ click chemistry or conjunction with other techniques; druggability optimization with 1,2,3-triazole groups; and intracellular self-assembly platforms with ring tension reactions, which are presented from the viewpoint of drug development. There is a reasonable prospect that bioorthogonal coupling reactions will accelerate the screening of lead compounds, the designing strategies of small molecules and expand the variety of designed compounds, which will be a new trend in drug development in the future.

Antivirulence C-Mannosides as Antibiotic-Sparing, Oral Therapeutics for Urinary Tract Infections

Gram-negative uropathogenic Escherichia coli (UPEC) bacteria are a causative pathogen of urinary tract infections (UTIs). Previously developed antivirulence inhibitors of the type 1 pilus adhesin, FimH, demonstrated oral activity in animal models of UTI but were found to have limited compound exposure due to the metabolic instability of the O-glycosidic bond (O-mannosides). Herein, we disclose that compounds having the O-glycosidic bond replaced with carbon linkages had improved stability and inhibitory activity against FimH. We report on the design, synthesis, and in vivo evaluation of this promising new class of carbon-linked C-mannosides that show improved pharmacokinetic (PK) properties relative to O-mannosides. Interestingly, we found that FimH binding is stereospecifically modulated by hydroxyl substitution on the methylene linker, where the R-hydroxy isomer has a 60-fold increase in potency. This new class of C-mannoside antagonists have significantly increased compound exposure and, as a result, enhanced efficacy in mouse models of acute and chronic UTI.