Metabolomic Approaches in Assessing the Insecticidal Activity of the Extracts from Argemone ochroleuca Sweet (Papaveraceae) Against Three Diverse Crop Pests of Economic Importance

For years, crop protection from pest attack, has been dominated by the use of synthetic insecticides. However, many of them can cause severe environmental problems and human health. In this context, the use of plant extracts constitutes an alternative to avoid this kind of contaminants. In this work, we investigated the chemical constituents and insecticidal activity of different extracts of leaves and stems of Argemone ochroleuca Sweet (Papaveraceae) against three economically important pests Sitophilos zeamais (Coleoptera:Curculionidae), Galleria mellonella (Lepidoptera:Pyralidae) and Xyleborus ferrugineus (Coleoptera:Scolytidae). A GC-MS analysis mostly revealed the presence benzylisoquinoline alkaloids such as allocryptopine, protopine, among others. For the insecticidal activity, after nine hours of contact, the methanolic leaves extract showed a 100 % of mortality, followed by the dichloromethane stems extract with up to 93 % of mortality. The results suggest that the benzylisoquinoline alkaloids are involved in the insecticidal activity through the octopaminergic system of the tested insects.

Neuropharmacological Effects of the Dichloromethane Extract from the Stems of Argemone ochroleuca Sweet (Papaveraceae) and Its Active Compound Dihydrosanguinarine

Argemone ochroleuca Sweet (Papaveraceae) is used in folk medicine as a sedative and hypnotic agent. This study aimed to evaluate the anxiolytic-like, sedative, antidepressant-like, and anticonvulsant activities of a dichloromethane extract of A. ochroleuca stems (AOE), chemically standardized using gas chromatography-mass spectrometry (GC-MS), and its active compound dihydrosanguinarine (DHS). The anxiolytic-like, sedative, antidepressant-like, and anticonvulsant activities of the AOE (0.1-50 mg/kg p.o.) and DHS (0.1-10 mg/kg p.o.) were evaluated using murine models. A possible mechanism for the neurological actions induced by the AOE or DHS was assessed using inhibitors of neurotransmission pathways and molecular docking. Effective dose 50 (ED50) values were calculated by a linear regression analysis. The AOE showed anxiolytic-like activity in the cylinder exploratory test (ED50 = 33 mg/kg), and antidepressant-like effects in the forced swimming test (ED50 = 3 mg/kg) and the tail suspension test (ED50 = 23 mg/kg), whereas DHS showed anxiolytic-like activity (ED50 = 2 mg/kg) in the hole board test. The AOE (1-50 mg/kg) showed no locomotive affectations or sedation in mice. A docking study revealed the affinity of DHS for α2-adrenoreceptors and GABAA receptors. The anxiolytic-like and anticonvulsant effects of the AOE are due to GABAergic participation, whereas the antidepressant-like effects of the AOE are due to the noradrenergic system. The noradrenergic and GABAergic systems are involved in the anxiolytic-like actions of DHS.

Synthesis and Insecticidal Evaluation of Chiral Neonicotinoids Analogs: The Laurel Wilt Case

Xyleborus sp beetles are types of ambrosia beetles invasive to the United States and recently also to Mexico. The beetle can carry a fungus responsible for the Laurel Wilt, a vascular lethal disease that can host over 300 tree species, including redbay and avocado. This problem has a great economic and environmental impact. Indeed, synthetic chemists have recently attempted to develop new neonicotinoids. This is also due to severe drug resistance to “classic” insecticides. In this research, a series of neonicotinoids analogs were synthesized, characterized, and evaluated against Xyleborus sp. Most of the target compounds showed good to excellent insecticidal activity. Generally, the cyclic compounds also showed better activity in comparison with open-chain compounds. Compounds R-13, 23, S-29, and 43 showed a mortality percent of up to 73% after 12 h of exposure. These results highlight the enantioenriched compounds with absolute R configuration. The docking results correlated with experimental data which showed both cation-π interactions in relation to the aromatic ring and hydrogen bonds between the search cavity 3C79 and the novel molecules. The results suggest that these sorts of interactions are responsible for high insecticidal activity.

l-Proline as a Valuable Scaffold for the Synthesis of Novel Enantiopure Neonicotinoids Analogs

In this research, six neonicotinoid analogs derived from l-proline were synthesized, characterized, and evaluated as insecticides against Xyleborus affinis. Most of the target compounds showed good to excellent insecticidal activity. To the best of our knowledge, this is the first report dealing with the use of enantiopure l-proline to get neonicotinoids. These results highlighted the compound 9 as an excellent candidate used as the lead chiral insecticide for future development. Additionally, molecular docking with the receptor and compound 9 was carried out to gain insight into its high activity when compared to dinotefuran. Finally, the neurotoxic evaluation of compound 9 showed lower toxicity than the classic neonicotinoid dinotefuran.