Synthesis and fungistatic activity of new groups of 2,4-dihydroxythiobenzoyl derivatives against phytopathogenic fungi

Investigation of 2,4-Dihydroxylaryl-Substituted Heterocycles as Inhibitors of the Growth and Development of Biotrophic Fungal Pathogens Associated with the Most Common Cereal Diseases

Climate change forces agriculture to face the rapidly growing virulence of biotrophic fungal pathogens, which in turn drives researchers to seek new ways of combatting or limiting the spread of diseases caused by the same. While the use of agrochemicals may be the most efficient strategy in this context, it is important to ensure that such chemicals are safe for the natural environment. Heterocyclic compounds have enormous biological potential. A series of heterocyclic scaffolds (1,3,4-thiadiazole, 1,3-thiazole, 1,2,4-triazole, benzothiazine, benzothiadiazine, and quinazoline) containing 2,4-dihydroxylaryl substituents were investigated for their ability to inhibit the growth and development of biotrophic fungal pathogens associated with several important cereal diseases. Of the 33 analysed compounds, 3 were identified as having high inhibitory potential against Blumeria and Puccinia fungi. The conducted research indicated that the analysed compounds can be used to reduce the incidence of fungal diseases in cereals; however, further thorough research is required to investigate their effects on plant-pathogen systems, including molecular studies to determine the exact mechanism of their activity.

Easy S-Alkylation of Arylthioureas and 2-Mercaptobenzothiazoles Using Tetraalkylammonium Salts under Transition-Metal-Free Conditions

A highly-efficient and practical method for S-alkylation of arylthioureas was reported. Using tetraalkylammonium salts as alkylation reagents, a series of 68 S-substituted aryl-isothioureas were obtained in good to excellent yields under transition-metal-free conditions. The protocol features simple performance, broad functional group tolerance, good to excellent yields, and easily available starting materials, showing potential synthetic value for the preparation of diverse biologically or pharmaceutically active compounds.

N-Amino-1,8-Naphthalimide is a Regenerated Protecting Group for Selective Synthesis of Mono-N-Substituted Hydrazines and Hydrazides

A new route to synthesis of various mono-N-substituted hydrazines and hydrazides by involving in a new C-N bond formation by using N-amino-1,8-naphthalimide as a regenerated precursor was invented. Aniline and phenylhydrazines are reproduced upon reacting these individually with 1,8-naphthalic anhydride followed by hydrazinolysis. The practicality and simplicity of this C-N dihalo alkanes; developed a synthon for bond formation protocol was exemplified to various hydrazines and hydrazides. N-amino-1,8-naphthalimide is suitable synthon for transformation for selective formation of mono-substituted hydrazine and hydrazide derivatives. Those are selective mono-amidation of hydrazine with acid halides; mono-N-substituted hydrazones from aldehydes; synthesis of N-aminoazacycloalkanes from acetohydrazide scaffold and inserted to hydroxy derivatives; distinct synthesis of N,N-dibenzylhydrazines and N-benzylhydrazines from benzyl halides; synthesis of N-amino-amino acids from α-halo esters. Ecofriendly reagent N-amino-1,8-naphthalimide was regenerated with good yields by the hydrazinolysis in all procedures.

Synthesis and Antifungal Screening of 2-{[1-(5-Alkyl/arylalkylpyrazin-2-yl)ethylidene]hydrazono}-1,3-thiazolidin-4-ones

Two novel thiosemicarbazones and eight novel 2-{[1-(5-alkyl/arylalkylpyrazin-2-yl)ethylidene]hydrazono}-1,3-thiazolidin-4-ones were prepared and tested against a panel of eight fungal strains–Candida albicans ATCC 44859, Candida tropicalis 156, Candida krusei E 28, Candida glabrata 20/I, Trichosporon asahii 1188, Aspergillus fumigatus 231, Lichtheimia corymbifera 272, and Trichophyton interdigitale 445. 1,3-Thiazolidin-4-ones exhibited activity against all strains, the most potent derivative was 2-{[1-(5-butylpyrazin-2-yl)ethylidene]hydrazono}e-1,3-thiazolidin-4-one. Susceptibility of C. glabrata to the studied 1,3-thiazolidin-4-ones (minimum inhibitory concentrations (MICs) were in the range 0.57 to 2.78 mg/L) is of great interest as this opportunistic pathogen is poorly susceptible to azoles and becomes resistant to echinocandins. Antifungal potency of thiosemicarbazones was slightly lower than that of 1,3-thiazolidin-4-ones.

Synthesis of a new group of aliphatic hydrazide derivatives and the correlations between their molecular structure and biological activity

In view of the growing demand for new compounds showing biological activity against pathogenic microorganisms, such as pathogenic and phytopathogenic fungi, the objective of this study was to synthesize a new group of aliphatic and aromatic derivatives of hydrazide. In consequence of the reactions observed during synthesis, the resulting compounds retained their linear structure. Their structure and lipophilicity, measured by high-performance liquid chromatography (HPLC), were analyzed. Correlations were determined between the compounds' molecular parameters and biological activity against Fusarium solani and Fusarium oxysporum fungi. The investigated compounds were also examined for their antifungal activity against Aspergillus fumigatus. The obtained results indicate that compounds with fluorine-containing substituents penetrate the cell structure more effectively and are characterized by higher antifungal potential than analogues with different substituents.