Synthesis, biological evaluation and in silico computational studies of 7-chloro-4-(1H-1,2,3-triazol-1-yl)quinoline derivatives: search for new controlling agents against Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae.
The insecticidal and antifeedant activities of five 7-chloro-4-(1H-1,2,3-triazol-1-yl)quinoline derivatives were evaluated against the maize armyworm, Spodoptera frugiperda (J.E. Smith). These hybrids were prepared through a copper-catalyzed azide alkyne cycloaddition (CuAAC, known as a click reaction) and displayed larvicidal properties with LD50 values below 3 mg/g insect, and triazolyl-quinoline hybrid 6 showed an LD50 of 0.65 mg/g insect, making it 2-fold less potent than methomyl, which was used as a reference insecticide (LD50=0.34 mg/g insect). Compound 4 was the most active antifeedant derivative (CE50=162.1 µg/mL) with a good antifeedant index (56-79%) at concentrations of 250-1000 µg/mL. Additionally, triazolyl-quinoline hybrids 4-8 exhibited weak inhibitory activity against commercial acetylcholinesterase from Electrophorus electricus (electric-eel AChE) (IC50=27.7 µg/mL) as well as low anti-ChE activity on S. frugiperda larvae homogenate (IC50=68.4 µg/mL). Finally, molecular docking simulations suggested that hybrid 7 binds to the catalytic active site (CAS) of this enzyme and around the rim of the enzyme cavity, acting as a mixed (competitive and noncompetitive) inhibitor like methomyl. Triazolyl-quinolines 4-6 and 8 inhibit AChE by binding over the perimeter of the enzyme cavity, functioning as noncompetitive inhibitors. The results described in this work can help to identify lead triazole structures from click chemistry for the development of insecticide and deterrent products against S. frugiperda and related insect pests.