Lemongrass essential oil and its major component citronellol: evaluation of larvicidal activity and acetylcholinesterase inhibition against Anopheles sinensis.

Mosquito-borne diseases, such as malaria, dengue fever, and the Zika virus, pose significant global health challenges, affecting millions annually. Due to increasing insecticide resistance, there is a growing interest in natural alternatives for mosquito control. Lemongrass essential oil, derived from Cymbopogon citratus, has shown promising repellent and larvicidal properties against various mosquito species. In this study, we investigated the larvicidal effect of lemongrass oil and its major compounds on Anopheles sinensis, the primary malaria vector in China. GC-MS analysis identified the major compounds of lemongrass oil as ( +)-citronellal (35.60%), geraniol (21.84%), and citronellol (13.88%). Lemongrass oil showed larvicidal activity against An. sinensis larvae, with an LC₅₀ value of 119.20 ± 3.81 mg/L. Among the major components, citronellol had the lowest LC₅₀ value of 42.76 ± 3.18 mg/L. Moreover, citronellol demonstrated inhibitory effects on acetylcholinesterase (AChE) activity in An. sinensis larvae, assessed by homogenizing larvae at different time points following treatment. Molecular docking studies further elucidated the interaction between citronellol and AChE, revealing the formation of hydrogen bonds and Pi-Sigma bonds. Aromatic amino acid residues such as Tyr71, Trp83, Tyr370, and Tyr374 played a pivotal role in these interactions. These findings may contribute to understanding lemongrass oil's larvicidal activity against An. sinensis and the mechanisms underlying these effects.