In searching for novel fungicidal leads, the novel bioactive
succinate
dehydrogenase inhibitor (SDHI) derivatives were designed and synthesized
by the inversion of carbonyl and amide groups. Bioassay indicated
that compound 5i stood out with a broad spectrum of in
vitro activity against five fungi. Its EC50 value (0.73
μg/mL) was comparable to that of boscalid (EC50 of
0.51 μg/mL) and fluxapyroxad (EC50 of 0.19 μg/mL)
against Sclerotinia sclerotiorum. For Rhizoctonia cerealis, 5i and 5p with EC50 values of 4.61 and 6.48 μg/mL, respectively,
showed significantly higher activity than fluxapyroxad with the EC50 value of 16.99 μg/mL. In vivo fungicidal activity
of 5i exhibited an excellent inhibitory rate (100%) against Puccinia sorghi at 50 μg/mL, while the positive
control boscalid showed only a 70% inhibitory rate. Moreover, 5i showed promising fungicidal activity with a 60% inhibitory
rate against Rhizoctonia solani at
1 μg/mL, which was better than that of boscalid (30%). Compound 5i possessed better in vivo efficacy against P. sorghi and R. solani than boscalid. Molecular docking showed that even the carbonyl oxygen
atom of 5i was far from the pyrazole ring. It could also
form hydrogen bonds toward the hydroxyl hydrogen and amino hydrogen
of TYR58 and TRP173 on SDH, respectively, which consisted of the positive
control fluxapyroxad. Fluorescence quenching analysis and SDH enzymatic
inhibition studies also validated its mode of action. Our studies
showed that 5i was worthy of further investigation as
a promising fungicide candidate.
Synthesis, isomerism, and fungicidal activity against potato diseases of new (5 Z)-[2-(2,4,5-trioxopyrrolidin-3-ylidene)-4-oxo-1,3-thiazolidin-5-ylidene]acetate derivatives with 1,3-thiazolidine-4-one and pyrrolidine-2,3,5-trione moieties linked by an exocyclic C═C bond were described. Their structures were clearly confirmed by spectroscopic and spectrometric data (Fourier transform infrared spectroscopy, H andC nuclear magnetic resonance, and mass spectrometry), elemental analysis, and X-ray diffraction crystallography. A bioassay for antifungal activity in vitro against Phytophthora infestans, Fusariun solani, Alternaria solani, Rhizoctonia solani, and Colletotrichum coccodes demonstrated that 2,4,5-trioxopyrrolidin-1,3-thiazolidine derivatives exhibited a relatively broad spectrum of antifungal activity. One of the compounds showed considerable activity against all of the strains; in the case of F. solani, P. infestans, and A. solani, it possesses comparable or better fungicidal efficacy than the positive control Consento. Consequently, this compound is a promising fungicidal candidate for plant protection.
A series of novel 5-(2-hydroxypropyl)amino-1,2,3-thiadiazole and 5-(2-hydroxypropyl)sulfanyl-1,2,3-triazole derivatives were designed and synthesized as candidate fungicides. The new compounds were identified by NMR and IR spectroscopy, mass spectro metry, and elemental analysis. Their antifungal activities were evaluated.
Ligand-controlled
rhodium(I)-catalyzed denitrogenative transformations
of a range of 4-vinyl-1,2,3-thiadiazoles possessing electron-donating
substituents at the C5-position of the heterocycle have been demonstrated.
With [Rh(COD)2]BF4, vinylic 1,2,3-thiadiazoles
undergo an intramolecular transannulation reaction to afford substituted
furans. In contrast, the [Rh(COD)DPPF]BF4 catalytic system
inhibits the intramolecular reaction but promotes intermolecular transannulation
with both electron-deficient and electron-rich terminal alkynes, providing
access to densely functionalized thiophenes with unexpected regioselectivity.
Experimental and computational mechanistic studies were performed
to gain insights into the Rh(I)-catalyzed intramolecular transannulation
of vinylic 1,2,3-thiadiazoles, with a focus on understanding the influence
of the C5-substituent on reactivity and the role of the DPPF ligand.
Importantly, our crystallographic data uncovered that the true structure
of the organorhodium intermediate involved in Rh(I)-catalyzed denitrogenative
reactions of 1,2,3-thiadiazoles is likely to be a four-membered cyclometalated
Rh(III) complex.
Compound 6u exhibits ultrahigh fungicidal activity by acting at its potent target PcORP1 and induces systemic acquired resistance by activating the salicylic acid pathway.
Natural products are one of the resources for discovering novel fungicidal leads. As a natural fungicide, osthole was used as a coumarin-based lead compound for the development of novel fungicides. Here, a series of 3,4-dichloroisothiazolecontaining 7-hydroxycoumarins were rationally designed, synthesized, and characterized by introducing a bioactive substructure, 3,4-dichloroisothiazole, into the coumarin skeleton. In vitro bioassay indicated that compound 7g displayed good activity against Rhizoctonia solani, Physalospora piricola, Sclerotinia sclerotiorum, and Botrytis cinerea. Its median effective concentration (EC 50 ) value against each of these fungi fell between 0.88 and 2.50 μg/mL, which was much lower than that of osthole against the corresponding pathogen (between 7.38 and 74.59 μg/mL). In vivo screening validated that 7k exhibited 100%, 60%, and 20% efficacy against R. solani Kuḧn at 200, 100, and 50 μg/mL, respectively. RNA sequence analysis implied that growth inhibition of R. solani by 7k might result from potential disruptions of fungal membrane formation and intracellular metabolism. Furthermore, a field experiment with cucumber plants indicated that 7b showed 62.73% and 74.03% efficacy against Pseudoperonospora cubensis (Berk. & Curt.) Rostov. at rates of 12.5 g a.i./ha and 25 g a.i./ha, respectively, which showed no significant difference between 7b and osthole at 30 g a.i./ha. Our studies suggested that 7b, 7g, and 7k might be used as fungicidal leads for further optimization.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.