Acute toxicity tests and dyeing potentials of three azo dyes from Pyocyanin, produced by Pseudomonas aeruginosa from farmlands

Abstract

The admiration for colours by man has made dyes to have very useful applications on a great variety of materials. Pyocyanin (PCN) or 5-methyl-1-hydroxyphenazine, a phenazine derivative biosynthesized by Pseudomonas aeruginosa isolated from the stressed soil of a farmland at Awka was used to prepare three azo dyes namely, pyocyanin azophenol, pyocyanin azo-1-naphthol and pyocyanin azo-2-naphthol. The PCN was treated with SOCl2 to convert it to the chloro analogue. Treatment of chloro analogue with NaCN in ethanol and subsequent acid hydrolysis gave the carboxylic acid from which the amide was obtained after treatment with (NH4)2CO3 and heat. The amide was converted to the amine by Hoffman’s amide degradation. The amine was diazotized and coupled with phenol, 1-naphthol and 2-naphthol to give the three azo dyes respectively. UV-VIS and infrared spectra of the compounds agreed with the assigned structures. Acute Toxicity (LD50) tests showed the compounds to be reasonably non-toxic. Dyeing potentials of the Pyocyanin (PCN), PCN azophenol, PCN azo-1-naphthol and PCN azo-2-naphthol by mordant dyeing on cotton, silk and nylon textile materials showed them to have blue, dark green, purplish-brown and red colours respectively. The dyes were reasonably fast to light, washing, rubbing, alkali and acid. Pyocyanin, Pyocyanin azophenol, Pyocyanin azo-1-naphthol and pyocyanin azo-2-naphthol produced from Pseudomonas aeruginosa isolated from farmland soil can be used effectively to dye cotton, silk and nylon textile materials.