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.
Los aceites esenciales y extractos de plantas,cultivadas de forma orgánica en la finca El Limonal Piedecuesta-Santander, Colombia, obtenidos por hidrodestilación asistida por microondas y percolación, se caracterizaron por cromatografía de gases acoplada a espectrometría de masas. La actividad insecticida se evaluó frente a larvas en tercer instar de Culex quinquefasciatus y en la enzima acetilcolinesterasa. La toxicidad se determinó en el modelo del pez cebra (Danio rerio). De ellos, el aceite esencial de Ruta graveolens fue el que presentó la mejor actividad larvicida, con CL50 7.20±0.19 μg/mL, una moderada inhibición de la enzima con IC50 44.98±1.1 μg/mL y moderada toxicidad con CL50 13.33±0.59 mg/L.
The ripe and dried fruits of organic pepper Capsicum chinense Jacq., obtained during planting, cultivation and harvesting, were subjected to solid-liquid extraction using a Soxhlet apparatus with hexane to remove non-polar compounds, and then with ethanol to remove the target compounds. The ethanolic extracts were characterized by gas chromatography-mass spectrometry (GC-MS) determining the composition of capsaicin (74.1%), dyhidrocapsaicin (8.9%), docosenamide (11.7%), ethyl linoleate (3.2%) and ethyl palmitate (2.1%). Three different bio-screenings: (1) the Trolox® equivalent antioxidant capacity (TEAC); (2) the inhibition of the enzyme acetylcholinesterase (AChE) and; (3) the embryo toxicity and the induction of phenotypic changes in the Zebrafish model were used. It was found that the ethanol extracts possess antioxidant activity (TAA 1800 ± 91 mmol Trolox®/kg extract) and AChE inhibition (IC 50 18.8 ± 0.5 µg/ml), as well as a moderate toxicity in zebrafish embryos (LC 50 39.7 ± 2.1 µg/ml), and good dual activity that make them extremely important not only for nutrition, but also as pharmacological substrates.
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