Secondary metabolites produced by solid-state fermentation of a neotropical Aspergillus flavus strain confer anti-mosquito activity with long shelf-life

Abstract

Fungal metabolites have shown promising potential as alternative tools for controlling mosquito larvae. Here, we evaluated the insecticidal activities of secondary metabolites (smAf) obtained by solid-state fermentation (SSF) of maize substrate inoculated with spores of the fungi Aspergillus flavus and evaluated the smAf toxicity against Aedes aegypti larvae. We further applied computational approaches to predict the interactions of three potential constituents of smAf with the A. aegypti acetylcholinesterases, which consists of a relevant physiological target for insecticides. Our results revealed that esters [Hexadecenoic acid, methyl ester; (E, E) − 9,12-octadecadienoic acid, methyl ester; (E, E) - 11,14-eicosadecanoic acid, methyl ester; (Z, Z) − 9,12-octadecadienoic acid, ethyl ester]; chromene [2,5,5,8a-tetramethyloctahydro-2Hchromene]; fatty acids [Hexadecenoic acid] and aromatic compounds [2-hydroxy-5-methoxybenzaldehyde, propyl ether; 3-hydroxy-4-propionylphenyl acetate; N-(2,4-dimethoxyphenyl) acetamide] were present in smAf. Toxicological bioassays demonstrated that smAf exhibited similar mosquitocidal activities against A. aegypti mosquito larvae just after obtention and after 48 storage months. Our computational predictions revealed the 2,5,5,8a-tetramethyloctahydro-2 H-chromene and acetylcholinesterase as the interaction with the highest binding energy (−7.3 kcal/mol). Our findings reinforce the mosquitocidal potential of smAf and demonstrate its efficacy, even after a long storage period.