de Oliveira_2025_Chem.Biol.Interact_420_111719

Dengue, Oropouche, lymphatic filariasis, and malaria remain serious public health problems in Brazil, transmitted by Aedes aegypti, Culex quinquefasciatus, and Anopheles darlingi resistant to pyrethroid insecticides. As alternatives, plant-derived natural insecticides have gained attention for their potential. In this study, we evaluated ishwarol B for its larvicidal activity and explored its mechanism of action against these mosquitoes. Ishwarol B exhibited larvicidal activity against all larvae (LC(50) from 19.57 to 26.23 microg/mL) and a residual effect of approximately 50 % observed, accompanied by increased production of H(2)O(2) (24.3 +/- 5 to 41.0 +/- 5 micromol of H(2)O(2) per gram(-1)), lipid peroxidation (11.00 +/- 2 to 22.67 +/- 2 mol of MDA per gram(-1)), and protein oxidation (10.00 +/- 1 to 17.00 +/- nM of reactive carbonyls/mg protein). Additionally, there was an increase in the activity of SOD (14.33 +/- 2 to 14.67 +/- 8 mU/mg protein), CAT (10.47 +/- 9 to 11.23 +/- 1 mmol of H(2)O(2) consumed/min/mg of protein), and GPx (11.91 +/- 1 to 16.46 +/- 2 mmol NADPH/min/mL). In contrast, AChE activity decreased (8.33 +/- 1 to 6.67 +/- 2 micromol/min/mg of protein), compared to negative control DMSO (105.30 +/- 2 to 111.30 +/- 3 micromol micromol/min/mg of protein), indicating enzymatic inhibition, further confirmed by an inhibition from 100 +/- 0 to 4.41 +/- 2 % (IC(50) of 3.46 microg/mL). Molecular docking revealed a binding energy of -8.4 kcal/mol and Ki = 0.695 microM, indicating a favorable interaction between ishwarol B and the AChE active site including Trp441, Tyr493, Tyr494, Ser280, Phe449, Ile446, Leu444, Gly445, Pro450, and Cys447. These findings confirm the broad mechanism of action of ishwarol B, highlighting its potential as a natural larvicide against the mosquito vectors investigated.