Novel trifluoromethyl sydnone derivatives: Design, synthesis and fungicidal activity.

Crop pathogens reduce the yield and quality of agricultural production. The development of new fungicides will help to sustain this protection and overcome fungicide resistance. Sydnone is a kind of mesoionic, which has a wide range of biological activities. The application of sydnones in agriculture is less, and the study of these compounds will lead to the discovery of new active compounds. In this study, we designed and synthesized a series of noval sydnone mesoionic derivatives by active substructure splicing. All compounds were characterized using 1H and 13C NMR spectroscopy. Among them, trifluoromethyl compound D17 showed good bioactivity against Pseudoperonospora cubensis (EC50 = 49 mg L-1) in vivo, the activity was similar to that of the control Kresoxim-methyl (EC50 = 44 mg L-1). However, the target of these compounds should not only be tyrosinase, and the mode of action needs to be further studied. In addition, the structure-activity relationship indicated that the trifluoromethyl group was more beneficial for antifungal activity. This is the first report that fluorine-containing N(3)-benzyl sydnone compounds have good fungicidal activity. These results will provide a basis for the development of sydnone mesoionic as new lead fungicidal agents.

Discovery of novel iminosydnone compounds with insecticidal activities based on the binding mode of triflumezopyrim.

Triflumezopyrim (TFM) is a new mesoionic insecticide developed by DuPont. Like other neonicotinoid insecticides, it binds to the orthosteric site of the nicotinic acetylcholine receptor (nAChR), but the binding mode has not been reported. Nicotinic acetylcholine binding proteins (nAChBPs) are ideal alternative structure for nAChRs. In this study, molecular docking, molecular dynamics (MD) simulations, binding free energy calculation, and per-residue binding free energy decomposition were used to study the binding modes of TFM and other 12 mesoionic insecticides. By comparing the binding free energy and the insecticidal activity, it was found that the sub-pocket around the benzyl group of the mesoionic insecticide is the key area for maintaining its activity, which is composed of A: Val116, A: Met124, A: Ile126, B: Trp155 and B: Val156. In order to verify the druggability of the sub-pocket, a series of iminosydnone compounds were designed and synthesized based on the structure of the sub-pocket. The lethality rate of compound 1 against Mythimna separata were 100% at 500 mg/L. Our research provides a basis for designing new mesoionic insecticides based on structure.

Fluorogenic iminosydnones: bioorthogonal tools for double turn-on click-and-release reactions.

In this article, we report the synthesis and use of iminosydnone-based profluorophores as bioorthogonal cleavable linkers for imaging applications. These linkers react with cycloalkynes via subsequent [3+2] cycloaddition and retro Diels-Alder reactions, allowing simultaneous release of two dyes in biological media.

Bioorthogonal release of sulfonamides and mutually orthogonal liberation of two drugs.

Sulfonamide derivatives have been used in pharmaceutics for decades. Here we report a new approach to release sulfonamides efficiently using a bioorthogonal reaction of sulfonyl sydnonimines and dibenzoazacyclooctyne (DIBAC). The second-order rate constant of the cycloaddition reaction can be up to 0.62 M-1 s-1, and the reactants are highly stable under physiological conditions. Most significantly, we also discovered the mutual orthogonality between the sydnonimine-DIBAC and benzonorbornadiene-tetrazine cycloaddition pairs, which can be used for selective and simultaneous liberation of sulfonamide and primary amine drugs.

Design and synthesis of novel hybrid sydnonimine and prodrug useful for glaucomatous optic neuropathy.

Synthesis and bioactivity of novel dual acting nitric oxide releasing and reactive oxygen scavenging hybrid compound SA-2 is described. The hybrid molecule SA-2 significantly increased the superoxide dismutase enzyme level and protected the photoreceptor cells from H2O2 induced oxidative stress. Synthesis of ocular esterase sensitive aceloxy alkyl carbamate prodrug SA-4 with improved aqueous half-life is achieved to aid topical ocular formulation. This class of hybrid molecule and prodrug may have dual potential of improved IOP lowering and neuroprotection in glaucomatous optic neuropathy.

Synthesis of 4-fluoromethylsydnones and their participation in alkyne cycloaddition reactions.

We report the synthesis and some structural studies of 4-trifluoromethyl, 4-difluoromethyl-, and 4-monofluoromethylsydnones. All but the latter compounds are stable and represent effective precursors to a range of pyrazoles after cycloaddition reactions with alkynes. The cycloadditions are generally highly regioselective and provide 5-fluoromethylpyrazole products, although we have observed that Bn-substituted sydnones can provide an unexpected alkyne insertion mode that generates the 3-fluoromethyl isomer.

Regioselective reaction: synthesis, characterization and pharmacological activity of some new Mannich and Schiff bases containing sydnone.

A novel series of 1-substituted aminomethyl-3-[1-(4-isobutylphenyl)ethyl]-4-(3-aryl-4-sydnonylidene) amino-1,2,4-triazol-5-thiones (9), was prepared from the 3-[1-(4-isobutylphenyl)ethyl]-4-(3-aryl-4-sydnonylidene) amino 5-mercapto-1,2,4-triazoles (8) by aminomethylation with formaldehyde and secondary amine. The structures of Schiff bases (8) and Mannich bases (9) were characterized on the basis of IR, NMR, mass spectra1 data and elemental analysis. The newly synthesized compounds were screened for their anti-inflammatory and analgesic activities. Mannich bases (9) carrying piperidine and morpholine residues showed promising anti-inflammatory and analgesic activity.

Sydnones: a brief review.

Sydnones are mesoionic heterocyclic aromatic compounds. They have been widely studied for some important biological activities like antiviral, antitumor, antimicrobial, anti-inflammatory, anticancer, analgesic, anthelmintic and antihypertensive activities. The aim of the present article is to review the available information on sydnones and the derivatives of sydnones and also a look at the future perspectives.

Synthesis and characterization of hydroxylated mesocarb metabolites for doping control.

The synthesis and method of analysis of hydroxylated mesocarb metabolites are described. Six potential hydroxylated mesocarb metabolites were prepared, characterized, and compared with the mesocarb metabolites synthesized enzymatically in vitro using human liver proteins and also compared with metabolites extracted from human urine after oral administration of mesocarb. p-Hydroxymesocarb was the most prevalent metabolite (conjugated and non-conjugated) observed. With respect to doping analysis, synthesis of p-hydroxymesocarb, the main urinary metabolite of mesocarb, and its availability as a reference material is important.

Cross coupling of bromo sydnones: development of a flexible route toward functionalized pyrazoles.

The application of a Suzuki cross coupling approach to a range of C-4 substituted sydnones from a 4-bromosydnone is described. Moreover, the potential of this approach to prepare a diverse range of pyrazoles is demonstrated.

Synthesis and antimicrobial activities of a new series of 4-S-[4(1)-amino-5(1)-oxo-6(1)-substituted benzyl-4(1),5(1)-dihydro-1(1),2(1),4(1)-triazin-3-yl]mercaptoacetyl-3-arylsydnones.

The synthesis of some 4-S-(4(1)-amino-5(1)-oxo-6(1)-substituted benzyl-4(1),5(1)-dihydro-1(1),2(1),4(1)-triazin-3-yl)mercaptoacetyl-3-arylsydnones by the reaction of 3-aryl-4-bromoacetylsydnones with 6-substituted-4-amino-3-mercapto-1,2,4-triazin-5-ones is described. The IR, (1)H NMR, mass spectra and elemental analysis characterized the newly synthesized compounds. The synthesized compounds were screened for their antimicrobial activity. All the compounds showed higher activity than that of standard drug during antimicrobial studies and the activity was comparable with the standard drug for antifungal activity.

Novel analogues of sydnone: synthesis, characterization and antibacterial evaluation.

New sydnone derivatives bearing a substituted phenyl ring at the 3-position have been synthesized. Two separate series of 3-(carboxyphenyl)sydnone derivatives have been prepared by cyclization of the corresponding N-nitroso-N-(carboxyphenyl)-glycine 3. The obtained 3-(carboxyphenyl)sydnones 4 were subjected to a series of different chemical reactions on the carboxylic acid group. Compound 5, the potassium salt of 4a, was reacted with alpha-chloroacetanilide derivatives 6 to give the corresponding esters 7. On the other hand, the acid hydrazide 9 was condensed with different aromatic aldehydes to give the corresponding arylidene derivatives 10. The synthesized compounds were tested for their antibacterial activities against both gram-positive and gram-negative organisms. Some of the test compounds exhibited high activity; among them, 10d is considered to be a lead compound possessing high broad-spectrum antibacterial activity.

Synthesis and biological testing of novel analogues of sydnone as potential antibacterial agents.

Several series of 3-phenylsydnone derivatives conjugated to well-known moieties with antibacterial activity were synthesized via several routes. These derivatives include 3-cyano-2-oxopyridine, 2-amino-3-cyanopyridine, 2-arylidene-1-ethylidenehydrazine and 2-aroyl-1-ethylidenehydrazine moieties. Thus, the key intermediate 3-(4-acetylphenyl)sydnone (3) was allowed to react with the appropriate aldehyde, ethyl cyanoacetate or malononitrile in presence of excess ammonium acetate in two steps (method 1) or through a one-pot reaction technique (methods 2 and 3) to give the corresponding sydnone derivatives 5 and 6, respectively. Moreover, condensation of compound 3 with hydrazine hydrate followed by the reaction with the appropriate aldehyde, mono- and dicarboxylic acid hydrazide yielded the corresponding sydnone derivatives 8, 9 and 10, respectively. Most of the synthesized compounds were screened for their in vitro antibacterial activity against various pathogenic organisms of both Gram-positive and Gram-negative bacteria. The minimum inhibitory concentrations (MICs) were determined using agar dilution method.

Synthesis and biological evaluation of a novel phenyl substituted sydnone series as potential antitumor agents.

A series of compounds containing an N-(4'-substituted-3'-nitrophenyl)sydnone moiety with potential antitumor activity was prepared based on active analogues. The rationale behind the design of these compounds is presented along with the 4-step synthetic route to the derivatives in the 4'-position of the phenyl sydnone framework. Out of the six novel compounds, the 4'-fluoro derivative has an improved activity against all three cell lines as compared to the earlier leads.

Sydnone derivatives. Part VII: Synthesis of some novel thiazoles and their pharmacological properties.

The synthesis of some 4-(arylsydnonyl)-2-(4-arylhydrazono-3-methyl-5-oxo-2-pyrazolin-1-yl)- thiazoles by reacting 1-thiocarboxamido-3-methyl-4-(aryihydrazono)-2-pyrazolin-5-ones with different 4-bromoacetyl-3-arylsydnones is described. A few compounds from this series were screened for their anti-inflammatory, analgesic, and CNS depressant activities. Among the tested compounds 6s, 6d, 6n, and 6u showed significant anti-inflammatory activity comparable with that of standard drug Ibuprofen. Compounds containing chlorine and carboxylic substituents are more active. 6f, 6r, and 6u showed marked analgesic activity and most of the compounds tested showed promising CNS depressant activity comparable with that of standard drug pentobarbitone.

Synthesis and antimicrobial evaluation of chalcone and syndrome derivatives of 4(3H)-quinazolinone.

The increasing clinical importance of drug-resistant bacterial pathogens has encouraged additional microbiological and antibacterial research. New chalcone and sydnone derivatives of 4(3H)-quinazolinone were synthesized and evaluated for their antibacterial and antifungal activity. The microorganisms used were Escherichia coli ATCC 25922 as Gram-negative bacteria, Staphylococcus aureus ATCC 19433 as Gram-Positive bacteria and Candida albicans as yeast like fungi. The most potent compound was the nitroso derivative 6b, which exhibits interesting antibacterial and antifungal activities.

1,5-benzodiazepine derivatives of 3-arylsydnones: synthesis and antimicrobial activity of 3-aryl-4-[2'-aryl-2',4',6',7'-tetrahydro-(1'H)-1',5'-benzodiazepine-4' -yl]sydnones.

The alpha-beta-unsaturated ketones of 3-arylsydnones (Ia-y) were treated with 1,2-phenylenediamine to obtain the 3-aryl-4-[2'-aryl- 2',4',6',7'-tetrahydro-(1'H)-1',5'-benzodiazepine-4'-yl]sydnones (IIa-y) in high yield. All the new compounds synthesised were screened for antibacterial and antifungal activities.

Synthesis and antiinflammatory, analgesic, and antipyretic testing of 4-[1-oxo-(3-substituted aryl)-2-propenyl]-3-phenylsydnones and of 3-[4-[3-(substituted aryl)-1-oxo-2-propenyl]phenyl]sydnones.

Two series of styrylcarbonyl 3-phenylsydnone derivatives, 4-[1-oxo-(3-substituted aryl)-2-propenyl]-3-phenylsydnones (series 1, 1-21) and 3-[4-[3-(substituted aryl)-1-oxo-2-propenyl]phenyl]sydnones (series II, 22-40), were synthesized and evaluated pharmacologically at a dose of 100 mg/kg po. Eleven compounds in series I plus one in series II and six in series I plus seven in series II were active in the carrageenan-induced edema and acetic acid-induced writhing assays, respectively. Compound 35 in the latter assay showed activity somewhat similar to that of the positive control drug, aspirin, administered at the same dosage. Compounds 11, 17, and 23 showed activity in both assays, and 23 also was active in the adjuvant-induced arthritis assay.

Platelet aggregation inhibiting and anticoagulant effects of oligoamines, XXIV: Interactions between oligosydnone imines and albumin or phospholipids.

Oligosydnone imines are strongly bound to albumin (alpha < 1%) in pure water. In saline, however, this effect is abolished (alpha approximately 80%). 4,4'-Propylene-bis-3-hexyl-sydnone-5-imine hydrochloride (1) moderately binds to phosphatidylcholine liposomes (PC, alpha approximately 34%). This is increased by phosphatidylethanolamine (PE). In PC/PE vesicles alpha is about 7%. The binding is further enhanced by the incorporation of negatively charged phospholipids (PL) like phosphatidylserine (PS). In PC/PE/PS liposomes complete binding of 1 can be achieved. This holds especially true if the composition of the liposomes is similar to the PL composition of platelet membranes. The results suggest that the antiplatelet activity of 1 is mediated by the bindings to negatively charged PL in the platelet membrane.