Chemical design and toxicity evaluation of new pyrimidothienotetrahydroisoquinolines as potential insecticidal agents

Preparation, Agricultural Bioactivity Evaluation, Structure-Activity Relationships Estimation, and Molecular Docking of Some Quinazoline Compounds

Quinazoline compounds have gained significant attention in the fields of agriculture and chemistry due to their diverse activities. In this study, we focused on a series of quinazoline derivatives (4a-l). The objectives involved multiple aspects, including preparation, evaluation of their agricultural bioactivity against the maize aphid (Rhopalosiphum maidis), estimation of the structure-activity relationships (SAR), and conducting molecular docking analysis. The results of the agricultural bioactivities revealed that compound (4b) possesses the highest insecticidal activity, and the other compounds have good potential as insecticidal agents. We conducted the SARs and also molecular docking investigation to elucidate the binding modes and interactions of these compounds with target proteins relevant to the agricultural bioactivity. The docking results provided valuable information on the binding affinities and molecular interactions, aiding in the rationalization of the observed bioactivity trends. The enzyme, acetylcholinesterase (AChE), was docked with the 12 synthetic compounds (4a-l). Among these compounds, (4b), (4i), and (4e)exhibited the highest binding affinity, with docking scores (S) of -7.96, -7.83, and -7.73 kcal/mol, respectively. They were followed by compounds (4d) (S = -7.57 kcal/mol), (4c) (S = -7.53 kcal/mol), (4g) (S = -7.34 kcal/mol), (4f) (S = -7.23 kcal/mol), (4h) (S = -7.14 kcal/mol), (4k) (S = -6.61 kcal/mol), (4j) (S = -6.57 kcal/mol), (4a) (S = -6.28 kcal/mol), and finally (4l) (S = -6.01 kcal/mol). These compounds were shown to have a variety of binding interactions within the 2ACE active site, as evidenced by protein-ligand docking configurations. This study gives evidence that those compounds have AChE-inhibitory capabilities and, hence, may be used for AChE-targeting development. Also, the findings in this study highlight the potential of these compounds as agricultural agents and provide valuable insights for the design and development of some quinazoline derivatives with enhanced bioactivity for crop protection.

Synthesis and Biological Evaluation of Novel Pyrimidine Amine Derivatives Bearing Bicyclic Monoterpene Moieties

A series of novel pinanyl pyrimidine amine derivatives (1e~1n) and camphoryl pyrimidine amine derivatives (2b~2f) bearing bicyclic monoterpene moieties were designed and synthesized from natural and renewable nopinone and camphor. All chemical structures of target compounds were characterized by ¹H NMR, ¹³C NMR and HRMS spectra analyses, and the antimicrobial activities were evaluated. The results indicated that most compounds showed considerable antibacterial and antifungal activities against Klebsiella pneumoniae, Streptococcus pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Methicillin-Resistant Staphylococcus aureus (MRSA), Bacillus cereus and Candida albicans. Among them, 1f showed potent antibacterial activity against all tested bacteria, 1i exhibited excellent inhibition against Streptococcus pneumoniae (1 μg/mL) and Escherichia coli (1 μg/mL), which was better than the control drug amikacin (2 μg/mL). As to antifungal activity against Candida albicans (C. albicans), compound 1l showed comparable activity (16 μg/mL) to the control drug ketoconazole. Furthermore, five active compounds with better antimicrobial activities also showed anti-inflammatory potencies against mouse mononuclear macrophages leukemia cells (RAW). Especially, 1f (IC₅₀ = 1.37 μM) and 2f (IC₅₀ = 1.87μM) are more potent than the control drug aspirin (IC₅₀ = 1.91 μM).

Synthesis, SAR studies, and insecticidal activities of certain N-heterocycles derived from 3-((2-chloroquinolin-3-yl)methylene)-5-phenylfuran-2(3H)-one against Culex pipiens L. larvae

An acid hydrazide derivative was synthesized and transformed into a variety of valuable N-heterocycles such as pyridazinone, oxadiazole, triazolopyridazinone, and triazole derivatives via reactions with certain carbon electrophiles such as 4-methoxybenzaldehyde, indole-3-carbaldehyde, pentan-2,4-dione, and carbon disulfide. The chemical structures of all prepared compounds were verified via their analytical and spectroscopic data. The insecticidal activity of the N-heterocycles was evaluated against field and lab strains of the third larval instar of Culex pipiens. All tested compounds exhibited higher larvicidal activity against the lab strains compared to the field strains, with dissimilar ratios. The obtained results demonstrate that the high toxicity achieved by oxadiazole followed the order of furanone, pyridazinone and hydrazide, with lower LC₅₀ values of the hydrazone and N-acetylpyridazinone derivatives compared to that of imidacloprid. Interestingly, these compounds are promising agents for insect pest control, especially since they are insoluble in water and can overcome the disadvantages of neonicotinoid applications in pest management programs.

A new series of N-heterocycles including pyridazinone, oxadiazole, triazolopyridazinone, and triazole derivatives were synthesized from the acid hydrazide via its reaction with certain carbon electrophiles.

Abdel-Raheem SA. Design, Synthesis, Characterization, and Insecticidal Bioefficacy Screening of Some New Pyridine Derivatives

A lot of insecticides are found nowadays, but neonicotinoids are considered the most famous. So, a series of pyridine derivatives neonicotinoids analogues, namely, 3-cyano-4,6-dimethylpyridine-2(1H)-one (1), 2-chloro-3-cyano-4,6-dimethylpyridine (2), 3-cyano-4,6-dimethylpyridine-2(1H)-thione (3), 3-cyano-4,6-distyrylpyridine-2(1H)-thione (4), 2-((3-cyano-4,6-distyrylpyridin-2-yl)thio)-N-phenylacetamide (5), 3-amino-N-phenyl-4,6-distyrylthieno[2,3-b]pyridine-2-carboxamide (6), 2-((3-cyano-4,6-distyrylpyridin-2-yl)thio)-N-(p-tolyl)acetamide (7), 3-amino-4,6-distyryl-N-(p-tolyl)thieno[2,3-b]pyridine-2-carboxamide (8), 2-((3-cyano-4,6-distyrylpyridin-2-yl)thio)-N-(4-methoxyphenyl)acetamide (9), and 3-amino-N-(4-methoxyphenyl)-4,6-distyrylthieno[2,3-b]pyridine-2-carboxamide (10), have been designed and synthesized in pure state, and their agricultural bioefficacy as insecticides against cowpea aphid Aphis craccivora Koch was screened. The structures of the synthesized compounds were verified by means of spectroscopic and elemental analyses. Insecticidal bioefficacy data illustrated that some compounds are excellent against cowpea aphid, and the bioefficacy of the rest of the tested compounds ranged from good to moderate against the same insects.