Synthesis of 4-Hydroxyazobenzene, a Promising Azo Dye for Antifungal Activity Against Macrophomina Phaseolina

Abstract

In the present study, an azo dye 4-hydroxyazobenzene was synthesized and its antifungal activity against a notorious soil-borne plant pathogen Macrophomina phaseolina was evaluated. The 4-hydroxyazobenzene was synthesized by azo coupling reaction between aniline diazonium salt and activated phenol. The azo coupling preferably occurred at para position of the phenol ring since the charge density get reinforced at this position and to minimize the steric hindrance between ortho positioned hydroxyl group. Azo coupling involved an electrophilic substitution reaction of phenyl diazonium cation with phenolate ion, the coupling partner. In vitro antifungal activity of the compound was assessed by dissolving the compound in dimethyl sulfoxide (DMSO) and preparing its different concentrations (ranging from 0.78 to 100 mg mL-1) in malt extract broth. All the concentrations of synthesized compound significantly (P≤0.05) reduced biomass of M. phaseolina by 31–49%. This study concludes that 4-hydroxyazobenzene can be used for control of M. phaseolina.

Amplicon sequencing identified a putative pathogen, Macrophomina phaseolina, causing wilt in African eggplant (Solanum aethiopicum) grown in Tanzania and Uganda

“…Further research is required to confirm the present results and inference. If these results/inferences are confirmed, then we need to develop and implement pathogen-specific management measures, such as using plant derived (Javaid and Khan, 2022) or synthesized (Zafar et al, 2022) compounds to inhibit M. phaseolina. The difference in putative causal agents between Uganda and Tanzania demonstrates the need for etiological studies before effective control methods can be developed and implemented.…”