EVALUATION OF THE INSECTICIDAL POTENTIAL OF THE LEAF EXTRACTS OF PSIDIUM GUAJAVA AND PIPER BETLE AGAINST AEDES AEGYPTI LARVAE.

Abstract

Plant-based insecticides are getting attention as an alternative mosquito control strategy because of the emergence of insect resistance to currently used synthetic chemicals. Further, their high safety profile makes them ideal candidates for environmental applications. The current study evaluated the insecticidal potential of Psidium guajava and Piper betle leaf extracts against Aedes aegypti through in vitro and in silico approaches. In laboratory studies, the LC50 of n-hexane extract of P. guajava and ethyl acetate extract of P. betle were 95.21 ppm and 217.7 ppm after 24-h exposure, respectively. The gas chromatography-mass spectrometry analysis identified important bioactive compounds, including caryophyllene (21.2%), globulol (19.9%), squalene (8.3%), and γ-muurolene (6.6%) in P. guajava and hydroxychavicol (57%), 5-allyl-2-hydroxyphenyl acetate (5.6%), phytol (2.3%), and safrole (1.8%) in P. betle extract. In silico analysis of these compounds with target proteins acetylcholinesterase (AChE), S-adenosylhomocysteine hydrolase (SAHH), and sterol carrier protein-2 (SCP-2) in Ae. aegypti larvae showed that squalene from P. guajava had a higher binding affinity with AChE (-8.4 kcal/mol) compared to globulol (-7.3 kcal/mol). However, conventional hydrogen bonding, which is stronger and more stable, was observed in the globulol-AChE complex. The in silico analysis of P. betle phytochemicals demonstrated that hydroxychavicol, phytol, and safrole had binding affinities of -6.1 kcal/mol, -6.0 kcal/mol, and -6.0 kcal/mol with SAHH, respectively. A minor increase in binding affinity was observed in the safrole-SAHH complex (-6.1 kcal/mol), whereas no change was observed in the 5-allyl-2-hydroxyphenyl acetate-AChE complex (-5.9 kcal/mol) in 2-ligand binding mode. Since these bioactive compounds target the important proteins in the developmental processes of mosquito larvae, they can further be evaluated to design natural and organic insecticides against Ae. aegypti.