SYNTHENSES, BIOLOGICAL EVALUATION, DOCKING AND ADMET PROFILING OF 4-AMINOANTIPYRINE DERIVATIVES

Abstract

Oxidative-stress, inflammation and glycation processes cause cell damages in the human body and may lead to aging and different disease conditions. Drugs that ameliorate oxidative stress can solve several disease pathologies. Drug development experiments in the early stages are expensive and time-consuming. These constraints could be minimised through computational approach. A 4-aminoantipyrine possesses biological properties including antioxidant and anti-inflammatory activities. However, information on its application as antiglycating agent is sparse. Therefore, this study was aimed at synthesising 4- aminoantipyrine derivatives and evaluating their antioxidant, anti-inflammatory, antiglycation and toxicity potentials using experimental, docking and ADMET profiling. Synthesis of Schiff bases was carried out by condensation of 4-aminoantipyrine with different substituted benzaldehydes. Ether derivatives were prepared from 4- aminoantipyrine Schiff bases via Williamson ether synthesis. The compounds were purified by solvent extraction and characterised using Fourier Transform Infra-Red (FTIR) spectroscopy, 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy, Mass Spectrometry (MS) and X-ray Diffraction (XRD) analysis. Cytotoxicity analysis was carried out using brine shrimps and 3T3 mouse fibroblast cell lines. The antioxidant, antiinflammatory and antiglycating activities were evaluated in vitro using 2,2-diphenyl-1- picrylhydrazyl radical, oxidative burst assay and human serum albumin solution; and compared with gallic acid, ibuprofen and rutin (standards), respectively. Molecular descriptors were obtained from Density Functional Theory (DFT) calculations and the binding affinity determined by molecular docking. Quantitative Structure-Activity Relationship (QSAR) model was used to predict the bioactivity of the compounds. A detailed ADMET (adsorption, distribution, metabolism, excretion, and toxicity) screening was done in-silico. Data were analysed by descriptive statistics. Fifty-eight compounds (thirty Schiff bases and twenty-eight ether derivatives) were synthesised out of which 24 were new. A newly synthesised 4-((2-chloro-4- fluorobenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one, had characteristic FTIR ῡmax at 1593 cm-1 for C=N (azomethine bond). The 1H-NMR spectrum showed seven methine signals at 9.91, 8.22, 7.55, 7.49, 7.40, 7.36 and 7.34 and two methylvi signals at 3.21and 2.47 ppm. The 13C NMR displayed seven quaternary, nine methine and two methyl carbons. The MS showed the molecular ion at 343 m/z corresponding to C18H15ClFN3O. The XRD showed a monoclinic unit cell and theta of 66.66o. None of the compounds was cytotoxic against normal cell lines (Cytotoxicity (3T3Cell-line) % inhibition ≤ 25%). Five of the compounds possessed antioxidant activity, with 4-((4- hydroxy-3-methoxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyraz-ol-3- one having similar activity (IC50 =111.10±1.80 µM) as gallic acid (IC50 = 111.60±2.40 µM). Four of the compounds exhibited anti-inflammatory activities with 4-((2,3- dihydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one having a lower IC50 (0.01±0.02 µM) than that of ibuprofen (11.20±1.90µM). Eight of the compounds possessed moderate antiglycation activity (IC50 = 321.16±5.70- 856.80±2.80µM) when compared to standard (IC50 = 282.40±0.80 µM). The DFT calculations and molecular docking confirmed compounds 4-((3,4- dihydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3 one and 4- ((2,3-dihydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one with best activities among the tested compounds. The molecular descriptors (EHOMO, ELUMO, polarisability, dipole moment and polar surface area) were responsible for the biological activities of the compounds. All the synthesised compounds demonstrated acceptable outcome in oral bioavailability, lipophilicity, pharmacokinetics, and toxicity prediction. The synthesised 4-aminoantipyrine derivatives were non-toxic and some possessed antiinflammatory, antioxidant and antiglycation properties making them potential drug candidates.