Synthesis, kinetics, structure-activity relationship and in silico ADME studies of new diazenyl azo-phenol derivatives against urease, SARS-CoV-2 main protease (Mpro) and ribosomal protein S1 (RpsA) of Mycobacterium tuberculosis

Abstract

In the present study, a new series of diazenyl azo-phenol derivatives (TC-1 to TC-8) have been synthesized via diazo-coupling approach between substituted aromatic amines and phenol derivatives produced azo–phenol compounds in moderate to good yields (40–80%). The appearance of characteristic prominent peak of azo derivatives i.e. N=N peak at 1500–1400cm−1 and disappearance of NH2 stretch at 3500–3200 cm−1, presence of a broad OH stretch in the range of 3300–3000 cm−1 in FTIR spectra, while presence of OH peak in spectral range of 15–10 ppm and aromatic protons in the region of 8.0–6.0 ppm and disappearance of NH2 peak in 5.0–4.0 spectral region in 1H NMR spectra confirms the synthesis of new diazenyl azo-phenol derivatives. Similarly, appearance of carbon attached with -N=N- group in the range of 149–144 ppm, C−OH in the range of 164–162 ppm, C−N of pyridine ring at 175 ppm, aromatic carbons at 140–108 ppm while aliphatic carbons at 21–20 ppm in 13C NMR spectra give strong indication of synthesis of proposed compounds and HRMS also confirmed the masses of proposed structure of diazenyl azo-phenol derivatives. In case of urease inhibition potential, the in vitro results suggested that the compound TC-6 (IC50 value 0.62 ± 0.04 µM) to be most active compared to the standard drug thiourea (IC50 value 21.44 ± 0.78 µM), kinetic analysis revealed that TC-6 behaved as a mixed-type inhibitor with irreversible mode of action. The SAR showed the stable docked complex due to the presence of dihydroxy hydrogen atoms in TC-6 (-6.01 kcal/mol) and strong binding interactions with the active site residues of the target protein urease (3LA4). The detailed in silico analysis of the diazenyl azo-phenol derivatives (TC-1 to TC-17) against the ribosomal protein S1 (RpsA) of Mycobacterium tuberculosis (4NNI) and main protease (Mpro) of SARS-CoV-2 (6LU7) was also performed and SAR showed that among all the docked compounds, TC-6 and TC-9 showed best docked conformational poses by exhibiting strong interactions with the active site residues of the target proteins (4NNI & 6LU7) with minimum binding energy values i.e. -5.36 kcal/mol and -4.84 kcal/mol respectively. The ADME calculations showed that the synthesized ligands quietly obey rule of five without any considerable violations.