4-Substituted-7-N-alkyl-N-acetyl 2-aminobenzothiazole amides: drug-like and non-xanthine based A2B adenosine receptor antagonists

Synthesis, SAR, Molecular Docking and Anti-Microbial Study of Substituted N-bromoamido-2-aminobenzothiazoles

BACKGROUND

Benzothiazoles are reported to have bioorganic and pharmaceutical chemistry applications.

INTRODUCTION

A series of substituted N-bromoamido-2-aminobenzothiazoles was synthesized from substituted anilines via 2-aminobenzothiazoles and it was further evaluated for its antimicrobial activity.

METHODS

All the newly synthesized compounds were characterized by FT-IR, NMR and mass spectra and purity profiles were studied by HPLC analysis. The antimicrobial testing (MIC determination) was newly performed with agar micro-broth dilution method for these analogs.

RESULTS

Among the synthesized compound 3b showed the highest activity with MIC value of 3.12 μg/mL against Bacillus, E. coli, S. aureus and Klebsiella and 6.25 μg/mL against C. albicans. The ADME properties as calculated by using Qikprop were found within acceptable range. Derivatives shows a good-moderate binding affinity towards target Cytochrome P450 14 alpha-sterol demethylase (CYP51) (PDB ID: 1EA1).

CONCLUSION

Our in-silico and in-vitro studies on a series of substituted aminobenzothiazoles may be helpful for further designing of more potent antimicrobials in future.

The aminopyridine-3,5-dicarbonitrile core for the design of new non-nucleoside-like agonists of the human adenosine A2B receptor

A new series of amino-3,5-dicyanopyridines (3-28) as analogues of the adenosine hA_2B receptor agonist BAY60-6583 (compound 1) was synthesized. All the compounds that interact with the hA_2B adenosine receptor display EC₅₀ values in the range 9-350 nM behaving as partial agonists, with the only exception being the 2-{[4-(4-acetamidophenyl)-6-amino-3,5-dicyanopyridin-2-yl]thio}acetamide (8) which shows a full agonist profile. Moreover, the 2-[(1H-imidazol-2-yl)methylthio)]-6-amino-4-(4-cyclopropylmethoxy-phenyl)pyridine-3,5-dicarbonitrile (15) turns out to be 3-fold more active than 1 although less selective. This result can be considered a real breakthrough due to the currently limited number of non-adenosine hA_2B AR agonists reported in literature. To simulate the binding mode of nucleoside and non-nucleoside agonists at the hA_2B AR, molecular docking studies were performed at homology models of this AR subtype developed by using two crystal structures of agonist-bound A_2A AR as templates. These investigations allowed us to represent a hypothetical binding mode of hA_2B receptor agonists belonging to the amino-3,5-dicyanopyridine series and to rationalize the observed SAR.

Facile synthesis of N-acyl 2-aminobenzothiazoles by NHC-catalyzed direct oxidative amidation of aldehydes

NHC-catalyzed direct amidation of aldehydes with 2-aminobenzothiazoles allowed the synthesis of N-acyl 2-aminobenzothiazoles proceeding via acyl azolium intermediates.

Recent developments in adenosine receptor ligands and their potential as novel drugs

Medicinal chemical approaches have been applied to all four of the adenosine receptor (AR) subtypes (A(1), A(2A), A(2B), and A(3)) to create selective agonists and antagonists for each. The most recent class of selective AR ligands to be reported is the class of A(2B)AR agonists. The availability of these selective ligands has facilitated research on therapeutic applications of modulating the ARs and in some cases has provided clinical candidates. Prodrug approaches have been developed which improve the bioavailability of the drugs, reduce side-effects, and/or may lead to site-selective effects. The A(2A) agonist regadenoson (Lexiscan®), a diagnostic drug for myocardial perfusion imaging, is the first selective AR agonist to be approved. Other selective agonists and antagonists are or were undergoing clinical trials for a broad range of indications, including capadenoson and tecadenoson (A(1) agonists) for atrial fibrillation, or paroxysmal supraventricular tachycardia, respectively, apadenoson and binodenoson (A(2A) agonists) for myocardial perfusion imaging, preladenant (A(2A) antagonist) for the treatment of Parkinson's disease, and CF101 and CF102 (A(3) agonists) for inflammatory diseases and cancer, respectively.