Targeting larvae and odorant-binding proteins for mosquito control: Experimental and in-silico investigations of Schiff bases containing aminophenol moiety

Abstract

Background: Controlling mosquitoes is crucial for public health globally. Presently, the emphasis is on transitioning from conventional insecticides to viable alternatives such as larvicide options. This study aims to determine the effectiveness of two Schiff base compounds as larvicides and repellents for mosquito control.

Methods: The stock solution of two Schiff base compounds (Z)-2-((2-hydroxybenzylidene)amino)phenol (MO) and (Z)-4-bromo-2-(((2-hydroxyphenyl)imino)methyl)-phenol (MY), was prepared in dimethyl sulfoxide and water in a 1:40 ratio. A total of ten 3^rd-4^th instar larvae of Anopheles larvae in duplicates were exposed to varying concentrations of the test compounds, mortality rate and lethal toxicity were evaluated per unit of time for data analysis. The compounds were also modelled as a repellent to Odorant Binding Protein (OBP) using molecular docking studies.

Results: The results showed that both compounds were highly effective in controlling the larvae in the laboratory, with LC₅₀ values ranging (24 to 96 hrs) from 36.922 mg/ml to 0.001 mg/L. Molecular docking experiment confirmed the potential of inhibiting the olfactory odorant protein binding role in the human host target. Computed data showed that both compounds were found to be lethal to the Anopheles mosquito larvae species. However, the 5-bromosalicylaldehyde was more active on the larvae when compared to 2-aminophenol with salicylaldehyde.

Conclusion: These findings indicate that the tested compounds have promising larvicidal and repellent activity, suggesting an integrative pest management strategy that first focuses on killing the larvae.

 

Keywords: Aminophenol; anopheles mosquito; larvicides; repellent; Schiff base.