Drug design and in-silico study of 2-alkoxylatedquinoline-3-carbaldehyde compounds: Inhibitors of Mycobacterium tuberculosis

Abstract

Tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB) is a deadly communicable disease that frequently affects the lungs. Current treatment protocols are bedeviled by extensive drug-resistant (XDR) and the evolution of multidrug-resistant (MDR-TB) strains. Virtual in-silico drug discovery tools were used to investigate thirty-two hypothetical 2-alkoxylatedquinoline-3-carbaldehyde compounds for screening against ten different diseases proteins based on drug-likeness, oral bioavailability, pharmacokinetics, global chemical reactivity and their theoretical binding affinities. Their chemical structures were optimized at the density functional theory (DFT) using Becke's three-parameter exchange functional with Lee–Yang–Parr correlation function (B3LYP) and the triple zeta basis set 6–311 in a vacuum using Gaussian 09 W software. Docking study using Pyrx and Discovery studio. Fourteen compounds; 4 - 6, 12 – 14, 19 – 22 and 27–30 complied with the established drug-likeness rules, however, five compounds 12, 13, 27, 28 and 29 exhibited no significant toxicity. Structural activity relationship revealed that shorter (n < 3) or longer (n > 5) alkyloxyl substituents at position-2 of the quinoline moiety reduces drug-likeness and increases toxicity. Individually, the binding energies obtained were (-8.9 kcal/ mole) against malaria for compound 12 and (-8.2 kcal/mole) against the diabetes for compound 29, both highest for the ten diseases investigated. Mycobacterium Tuberculosis proteins investigated. Molecular dynamics also confirms that 12 and 27 binds very well in the active pocket of Mycobacterium tuberculosis and calculated total free binding energy from MMPBSA is -97.53 ± 2.47 and -58.62 ± 2.94 kJ/mol respectively. The five lead compounds all had binding energies higher than the reference tuberculosis drugs; Isoniazid and Ethambutanol.