Syntheses, Characterisation and In-Vitro Antibacterial Studies of Aminoalkylnaphthol Derivatives against Staphylococcus Aureus & Pseudomonas Aeruginosa
Abstract
The emergence and rise in antimicrobial resistance of Staphylococcus aureus and Pseudomonas aeruginosa has caught the attention of the medical world and they remain the leading cause of most bacterial infection worldwide. There is an urgent need to design and develop new antibacterial agents to overcome this resistance issue. Recently, the synthesis of aminoalkylnaphthol as an antibacterial agent has intensified due to their attractive biological and pharmacological properties. The present study aims to synthesise, characterise and evaluate in-vitro antibacterial studies of aminoalkylnaphthol derivatives. The novel molecules were synthesised using one-pot three component (aldehyde, naphthol, amine) condensation reaction catalysed by MgSO₄ under solvent-free condition. The reaction progress was monitored with thin layer chromatography. Four derivatives were successfully synthesised with moderate yield ranging 55% to 80%. These compounds were characterised by determining the melting point and proton nuclear magnetic resonance (¹H-NMR) spectroscopy. The results show that all the synthesised compounds have melting point values which are comparable to the theoretical melting point range. The ¹H-NMR results showed singlet peaks which signifies -OH (δ 10.00 and 10.75 ppm) and central carbon -CH (δ 4.5 – 6.5 ppm). The doublet and triplet peaks (δ 6.20 – 7.35 ppm) showed presence of aromatic hydrogen. Also, the peaks in the range of δ 0.5 – 5 ppm signified the most shielded protons. The in-vitro antibacterial study was conducted by disk diffusion test to demonstrate the antibacterial activity possessed by the synthesised compounds. Compound A1 had the highest inhibition zone of 6mm for 100 μg of amount impregnated towards S. aureus. However, compound A3 had a zone of inhibition of 8mm for 100 μg towards P. aeruginosa. This study proved that the synthesised compounds have potential antibacterial activity towards S. aureus and P. aeruginosa.
