1,2,4-Oxadiazole as a potential scaffold in agrochemistry: a review.

N,O-containing heterocycles have been incorporated into various approved pesticides and pesticide candidates. The persistent challenge in contemporary crop protection lies in the continuous pursuit of novel N,O-heterocycle-containing compounds with pesticidal properties. Among them, the 1,2,4-oxadiazole scaffold is one of the most extensively explored heterocycles in new pesticide discovery and development.

Enantioselective Toxic Effects of Prothioconazole toward .

Prothioconazole (PTC) is a broad-spectrum triazole fungicide with one asymmetric center and consists of two enantiomers, -(-)-PTC and -(+)-PTC. To address the concern of its environmental safety, the enantioselective toxic effects of PTC on () were investigated. PTC racemates (-PTC) and enantiomers exhibited dose-dependent acute toxicity effects against at a concentration from 1 to 10 mg·L.

Toxicity Effects of Polystyrene Nanoplastics with Different Sizes on Freshwater Microalgae .

The ubiquitous nature of plastics, particularly nanoplastics, raises concern about their potential effects on primary producer microalgae. Currently, the impacts and potential mechanisms of nanoplastics on microalgae are not fully understood. In this study, the effects of two plain commercial polystyrene nanoplastics (PS-NPs) with different sizes (50 nm and 70 nm) on were assessed in a concentration range of 0-50 mg/L during 72 h exposure periods.

TBPEH-TBPB Initiate the Radical Addition of Benzaldehyde and Allyl Esters.

Tert-butylperoxy-2-ethylhexanoate (TBPEH) and tert-butyl peroxybenzoate (TBPB) promote the radical acylation of allyl ester with benzaldehyde to synthesize new carbonyl-containing compounds under solvent-free and metal-free conditions. This reaction is compatible with electron-donating and halogen groups and has excellent atom utilization and chemical selectivity. Furthermore, the synthetic compounds can further apply to the preparation of lactone, piperidine, tetrazole and oxazole.

Synthesis, biological activity and toxicity to zebrafish of benzamides substituted with pyrazole-linked 1,2,4-oxadiazole.

To find pesticidal lead compounds with high activity, a series of novel benzamides substituted with pyrazole-linked 1,2,4-oxadiazole was designed and synthesized by using the splicing principle of active substructures. The chemical structures of the target compounds were confirmed by H NMR, C NMR and HRMS. The preliminary bioassay showed that most compounds displayed good larvicidal activities against mosquito larvae at 10 mg L.

Structure-Based Bioisosterism Design, Synthesis, Biological Activity and Toxicity of 1,2,4-Oxadiazole Substituted Benzamides Analogues Containing Pyrazole Rings.

In order to discover pesticidal lead compounds with high activity and low toxicity, a series of novel benzamides substituted with pyrazole-linked 1,2,4-oxadiazole were designed via bioisosterism. The chemical structures of the target compounds were confirmed via H NMR, C NMR and HRMS analysis. The preliminary bioassay showed that most compounds exhibited good lethal activities against , , and at 500 mg/L.

Benzamides Substituted with Quinoline-Linked 1,2,4-Oxadiazole: Synthesis, Biological Activity and Toxicity to Zebrafish Embryo.

To develop new compounds with high activity, broad spectrum and low-toxicity, 17 benzamides substituted with quinoline-linked 1,2,4-oxadiazole were designed using the splicing principle of active substructures and were synthesized. The biological activities were evaluated against 10 fungi, indicating that some of the synthetic compounds showed excellent fungicidal activities. For example, at 50 mg/L, the inhibitory activity of (3-Cl-4-Cl substituted, 86.

Novel Pyridyl-Oxazole Carboxamides: Toxicity Assay Determination in Fungi and Zebrafish Embryos.

Eight novel pyridyl-oxazole carboxamides were evaluated against fungi and displayed good fungicidal activities against and . Preliminary bioassay results indicated that at 100 mg/L, compounds -, and exhibited 100% fungicidal activities against , and the compound to at 100%. Then, the zebrafish embryo acute toxicity test was performed to assess the toxicity of and .

1,2,4-Oxadiazole-Based Bio-Isosteres of Benzamides: Synthesis, Biological Activity and Toxicity to Zebrafish Embryo.

To discover new compounds with broad spectrum and high activity, we designed a series of novel benzamides containing 1,2,4-oxadiazole moiety by bioisosterism, and 28 benzamides derivatives with antifungal activity were synthesized. These compounds were evaluated against four fungi: , , , and . The results indicated that most of the compounds displayed good fungicidal activities, especially against .

Synthesis and Biological Activity of Benzamides Substituted with Pyridine-Linked 1,2,4-Oxadiazole.

To find pesticidal lead compounds with high activity, a series of novel benzamides substituted with pyridine-linked 1,2,4-oxadiazole were designed by bioisosterism, and synthesized easily via esterification, cyanation, cyclization and aminolysis reactions. The structures of the target compounds were confirmed by H-NMR, C-NMR and HRMS. The preliminary bioassay showed that most compounds had good larvicidal activities against mosquito larvae at 10 mg/L, especially compound , with a larvicidal activity as high as 100%, and even at 1 mg/L was still 40%; at 50 mg/L, all the target compounds showed good fungicidal activities against the eight tested fungi.

Synthesis and Pesticidal Activities of New Quinoxalines.

Natural products are a source of many novel compounds with biological activity for the discovery of new pesticides and pharmaceuticals. Quinoxaline is a fused -heterocycle in many natural products and synthetic compounds, and seven novel quinoxaline derivatives were designed and synthesized three steps. Pesticidal activities of title quinoxaline derivatives were bioassayed.

Synthesis and herbicidal activity of novel pyrazole aromatic ketone analogs as HPPD inhibitor.

Background: 4-Hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.

Evaluation of the toxic response induced by azoxystrobin in the non-target green alga Chlorella pyrenoidosa.

The top-selling strobilurin, azoxystrobin (AZ), is a broad-spectrum fungicide that protects against many kinds of pathogenic fungi by preventing their ATP production. The extensive use of AZ can have negative consequences on non-target species and its effects and toxic mechanisms on algae are still poorly understood. In this work, Chlorella pyrenoidosa that had been grown in BG-11 medium was exposed to AZ (0.

Salting-out-enhanced ionic liquid microextraction with a dual-role solvent for simultaneous determination of trace pollutants with a wide polarity range in aqueous samples.

In real aquatic environments, many occupational pollutants with a wide range of polarities coexist at nanogram to milligram per liter levels. Most reported microextraction methods focus on extracting compounds with similar properties (e.g.

Synthesis and insecticidal activity of novel pyrimidine derivatives containing urea pharmacophore against Aedes aegypti.

Background: Aedes aegypti is a major mosquito vector for the transmission of serious diseases, especially dengue and yellow fever. More than 1 billion people in developing countries are at risk. The widespread and continual use of pesticides can lead to resistant mosquitoes.

Facile and efficient synthesis and herbicidal activity determination of novel 1,2,4-triazolo[4,3-a]pyridin-3(2H)-one derivatives via microwave irradiation.

A series of novel 1,2,4-triazolo[4,3-a]pyridin-3(2H)-one derivatives were synthesized and identified by (1)H NMR, single crystal X-ray diffraction, elemental analysis or HRMS, and their herbicidal activities were determined at different concentrations. It was found that some of the title compounds possess high herbicidal activity. Furthermore, DFT calculation was used to study the SAR.

Activities of wogonin analogs and other flavones against Flavobacterium columnare.

In our on-going pursuit to discover natural products and natural product-based compounds to control the bacterial species Flavobacterium columnare, which causes columnaris disease in channel catfish (Ictalurus punctatus), we synthesized flavone and chalcone analogs, and evaluated these compounds, along with flavonoids from natural sources, for their antibacterial activities against two isolates of F. columnare (ALM-00-173 and BioMed) using a rapid bioassay. The flavonoids chrysin (1a), 5,7-dihydroxy-4'-methoxyflavone (11), isorhamnetin (26), luteolin (27), and biochanin A (29), and chalcone derivative 8b showed strong antibacterial activities against F.

Synthesis, crystal structure, herbicidal activities and 3D-QSAR study of some novel 1,2,4-triazolo[4,3-a]pyridine derivatives.

Background: 1,2,4-Triazolo[4,3-a]pyridine derivatives represent a new series of compounds that possess good herbicidal activity against Echinochloa crusgalli (L.) Beauv., Setaria faberii, Digitaria sanguinalis (L.

Microwave assistant one pot synthesis, crystal structure, antifungal activities and 3D-QSAR of novel 1,2,4-triazolo[4,3-a]pyridines.

A series of novel 1,2,4-triazolo[4,3-a]pyridines were synthesized, and their structures were characterized by (1) H NMR, MS, elemental analysis, and single-crystal X-ray diffraction analysis. The antifungal activities were evaluated. The antifungal activity results indicated that the compound 2b, 2g, 2p, and 2i exhibited good activities.

Design, synthesis, antifungal activities and 3D-QSAR of new N,N'-diacylhydrazines containing 2,4-dichlorophenoxy moiety.

A series of new N,N'-diacylhydrazine derivatives were designed and synthesized. Their structures were verified by 1H-NMR, mass spectra (MS) and elemental analysis. The antifungal activities of these N,N'-diacylhydrazines were evaluated.

Microwave assisted synthesis, antifungal activity and DFT theoretical study of some novel 1,2,4-triazole derivatives containing the 1,2,3-thiadiazole moiety.

In order to investigate the biological activity of 1,2,4-triazole compounds, seventeen novel 1,2,4-triazole derivatives containing 1,2,3-thiadiazole moieties were synthesized by multi-step reactions under microwave assisted conditions. The structures were characterized by 1H-NMR, 13C-NMR, MS and elemental analyses. The target compounds were evaluated for their in vivo fungicidal activities against Corynespora cassiicola, Pseudomonas syringae pv.

Structure, bioactivity and implications for environmental remediation of complexes comprising the fungicide hexaconazole bound to copper.

Background: In agricultural areas excessive amounts of toxic heavy metals are a growing threat to the environment and human health. Measures should be taken to minimise the risk of adverse health effects. Hence, we investigated the possibilities of hexaconazole (a commercial fungicidal) as a dual-function ligand that has heavy metal ions chelating and fungicidal activities.