6-Ishwarone: A novel eco-friendly botanical biocide inducing oxidative stress and disrupting defense enzyme activities in Aedes aegypti Linnaeus, 1762 and Anopheles darlingi Root, 1926 (Culicidae)

Aedes aegypti and Anopheles darlingi are vectors of dengue and malaria in Brazil. Currently, a alternative for their control is the use of essential oils (EOs) and their isolated compounds, which are environmentally friendly agents for larval management due to their low toxicity to non-target animals. Thus, in the study, the EO from Piper alatipetiolatum and its main compound were isolated and evaluated against larvae these mosquitoes, focusing on the mechanism of action. The lethal effect these products were also evaluated against non-target animals. The structure of the 6-ishwarone, a new sesquiterpene, was established using 1D and 2D NMR and HRAPCIMS data. 6-Ishwarone and the EO exhibited larvicidal activity (LC₅₀ from 25.03 to 42.58 μg/mL), accompanied by an overproduction of reactive oxygen and nitrogen species (36.67 ± 7 to 49.33 ± 1 %), an increase in both glutathione S-transferase (36.00 ± 8 to 80.67 ± 7 μmol/min/mg protein) and catalase activities (0.31 ± 0 to 0.50 ± 0 μmol of H₂O₂ consumed/min/mg of protein), followed by a decrease in acetylcholinesterase activity (36.00 ± 8 to 25.33 ± 1 μmol/min/mg protein) and a reduction in thiol content (30.00 ± 3 to 13.33 ± 3 μmol/mg protein). Furthermore, 6-ishwarone and the EO (LC₅₀ from 415.25 to 739.29 μg/mL), were less toxic to A. bouvieri, T. splendens, G. affinis, and D. indicus compared with α-cypermethrin (LC₅₀ from 0.23 to 0.35 μg/mL). These findings underscore the potential of these products for developing new mosquito control strategies.