Nanoemulsions of Leucaena leucocephala wood vinegar and main constituents exhibit high mosquitocidal activity against larvae of Culex pipiens L. (Diptera: Culicidae) via oxidative stress and neurotoxicity

Abstract

The present study investigates the mosquitocidal efficacy and biochemical effect of Leucaena leucocephala wood vinegar, its major chemical constituents (2-methoxy-p-creosol and o-guaiacol), and their nanoemulsion formulations against Culex pipiens larvae. The larvicidal bioassay revealed that the products exhibited time- and concentration-dependent toxicity against larvae, with nanoemulsion formulations significantly enhanced efficacy, especially for 2-methoxy-p-cresol, which achieved an exceptionally low LC₅₀ of 0.09 mg/L after 48 h of exposure. Biochemical assays confirmed substantial alterations in larval enzyme activity, indicating oxidative stress and neurotoxic effects induced by the treatments. Gas chromatography–mass spectrometry (GC–MS) analysis identified key bioactive compounds, including 2-methoxy-p-creosol (18.48 % peak area) and o-guaiacol (17.32 % peak area), which were further evaluated through molecular docking against target enzymes acetylcholinesterase (AChE), adenosine triphosphatase (ATPase), glutathione S-transferase (GST), and carboxylesterase (CarE). Docking results demonstrated strong binding affinities, suggesting potential mechanisms of action. These findings highlight the potential of L. leucocephala wood vinegar and its nanoformulations as eco-friendly, plant-based mosquito control agents with promising bioactivity at both physiological and molecular levels.