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.