Synthesis, Dyeing Potential, Antibacterial Activity and Docking Study of Azo Dye Derivatives

Abstract

Azo dyes are compounds containing electron-donating (D) and electron-accepting (A) functional groups through an azo p-conjugated linker. Most azo dyes are synthesized by diazotization of an aromatic primary amine, followed by coupling with one or more electron rich nucleophiles such as amino and hydroxyl group. Azo dyes are found to possess different pharmacological activities such as antitumor, anti-inflammatory, antimycotic, antimicrobial as well as antioxidant were previously reported. In this work, four p-nitroaniline azo dye derivatives (46, 47, 48 and 49) and four aniline azo dye derivatives (50, 51, 52 and 53) were synthesized by reacting diazonium salt with 2-naphthol (1-naphthol, resorcinol and phenol). The structures of the compounds were characterized using spectroscopic techniques (UV-Vis, 1H, 13C and DEPT-135 NMR). Dyeing action of azo dyes was evaluated in terms of dye exhaustion and fixation on cotton, wool, silk and polyester by using cold and hot methods. The better exhaustion and fixation values of dyes are all the four types of fibers in cold dyeing method than hot method reveals high suitability of cold dyeing method. The synthesized dye compounds were screened for their antibacterial activities against Escherichia coli and Staphylococcus aureus at different concentration (50, 75, and 100 mg/mL) and the result revealed that compound 46 showed potent activity against E.coli and S. aureus with 13.1± 0.76 and 13 ± 0 zone of inhibitions at 100 mg/mL concentrations respectively and compared to standard drug Penicillin (19.8 ± 0.28). Compounds 48 and 49 also showed higher activity against S. aureus (14 ± 0.5) and E.coli (14 ± 0.5) at 100 mg/mL respectively. Compound 52 and 53 showed no activity on S. aureus and E.coli respectively. Molecular docking of isolated compounds was done using Autodock vina version 4.2 software. Among the investigated ligands dye compound 46 and 47 exhibited better docking efficiency with DNA gyrase with binding affinity -7.4kcal/mol.