Antibacterial and phytotoxic activity of the Schiff’s bases of 5-phenyl-4-amino-3-mercapto-4H-1,2,4-triazole with the donor substituents in the 4th position on heterosystem

Background. Triazoles and Schiff’s bases have a high biological activity. For the practical use of the derivatives, their low toxicity is important. The purpose of this work was to investigate the antibacterial and phytotoxic properties of Schiff’s bases of 5-phenyl-4-amino-3-mercapto-4H-1,2,4-triazole with donor substituents in the 4th position of heterosystem. Materials and methods. In the study of antibacterial activity of the derivatives, corrosion-active 4-day association cultures of ammonifying and sulfate-reducing bacteria were used as a test culture of microorganisms. Sensitivity of bacteria to derivatives was determined by diffusion method in agar using sterile paper disks according to the standard method. In the investigation of phytotoxic activity of the derivatives, Lepidium sativum of the “Ajour” cultivar was used as a test plant. Seed germination and biometric indices (length, weight of the aboveground part and roots) of 5-day sprouts were determined, the phytotoxic effect of the derivatives was calculated. Experimental data were processed using methods of mathematical statistics. Results. The introduction of substituents does not provide for an increase in antibacterial properties of the studied compounds in relation to some corrosion active ammonifying and sulfate-reducing bacteria. Low activity was observed regarding the association culture of ammonifying bacteria to the compound without substituents in the phenyl fragment and the compound with fluor as a substituent in the phenyl fragment at a concentration of 2.0%. Derivatives with the methoxyl substituent in the phenyl fragment and with the hydroxyl substituent in the phenyl fragment did not show any antibacterial activity against the association culture of ammonifying bacteria isolated from ferrosphere in meat-peptone broth. Antibacterial action against the association of sulfate-reducing bacteria Desulfovibrio orizae with organic acid-producing bacteria Anaerotignum propionicum for derivatives were not detected. Phytotoxic properties were observed for the compound with the hydroxyl substituent that influenced the processes of growth in the test plant. Conclusion. The introduction of electron-donor substituents into the basic structure did not provide for an increase in antibacterial properties against corrosive bacteria. Phytotoxic properties were observed for the compound with the hydroxyl substituent in the phenyl fragment, which influenced the L. sativum growth processes by inhibiting growth of the above-ground part and roots. Other compounds either did not show any action, or demonstrated a weak stimulating effect on the growth and development of the test plant.

Synthesis and Biological Activity of Some Novel (Oxazol-5-yl-phenyl)-thiourea Derivatives

Aims: Synthesis and biological evaluation of some [(5-oxazolyl)-phenyl]-thiourea derivatives as potential antiviral agents. Background: (5-Oxazolyl)-phenyl derivatives were derived from the design of mycophenolic acid structurally related analogues. The (5-oxazolyl)-phenyl fragment is an excellent composition for many novel structure compounds having good pharmaceutical properties, such as immunosuppressive, antiviral and anticancer. In the present study, we present combinations of thiourea group and (5-oxazolyl)-phenyl fragment. The antiviral activity, cytotoxicity and IMPDH activity of the title compounds were evaluated in vitro bioassay. Objective: [(5-Oxazolyl)-phenyl]-thiourea derivatives containing different substituted benzene rings were synthesized by introducing thiourea linker. All the synthesized derivatives were screened for their in vitro antiviral evaluation and inosine monophosphate dehydrogenase activity. Method: A series of [(5-oxazolyl)-phenyl]-thiourea derivatives were synthesized by the reaction of thiocarbonyldiimidazole with amines. This was an effective method for introducing the thiourea group in the (5-oxazolyl)-phenyl structure. All of the synthesized derivatives were screened for their in vitro antiviral activity against influenza A virus, coxsackievirus B3, herpes simplex virus type 1 and inosine monophosphate dehydrogenase activity. Result: The results of the screening revealed that compounds 4i, 4j, 4k, 7m, 7n and 7o showed comparable activity towards IMPDH compared the control drug. Compounds 4k, 4l, 7m and 7n exhibited potent activity towards both RNA virus influenza A virus, coxsackievirus B3 and DNA virus HSV-1 at low micromolar concentrations. The activities of most compounds directly linked to the substituted benzene ring by the thiourea group were superior to those of the compounds which had the methylene linkage. Conclusion: The in vitro biological assays indicated that most of target molecules having combinations of thiourea group and (5-oxazolyl)-phenyl fragment exhibited antiviral activity and IMPDH activity compared the control drugs.

ACID-BASE PROPERTIES OF -UNSATURATED KETONES OBTAINED FROM REACTION OF 5-FORMYL-8-HYDROXYQUINOLINE WITH P-SUBSTITUTED ACETOPHENONES

Chalcones (α,β-unsaturated ketones) containing aromatic or heterocyclic radicals are highly reactive, allowing the synthesis of novel organic compounds. In this study, the dissociation constants (pKa) of seven chalcones derived from 8-hydroxyquinoline were determined and the influence on dissociation of substituents in the phenyl group (-CH3, -OCH3, -N(CH3)2, -Cl, -Br, and -NO2) was analysed. pKa values are important because they determine the pH at which ligands are fully deprotonated -when they show their maximum chelating properties- and determine the ligands interactions at different pH values. The chalcones’ pKa’s were calculated by visible ultraviolet spectroscopy in a water-ethanol (1:1) mixture using the Henderson-Hasselbach equation. It was shown that the 8-hydroxyquinolinic fragment has a large electron donor effect on the π system of the chalcones. The introduction of substituents (R) in the phenyl fragment of the chalcones slightly affected the dissociation of the hydroxyl group and the protonation of the nitrogen in the hydroxyquinoline fragment. The acceptor substituents (Cl, Br, NO2) increased the polarity of OH- and its acidity. Nitrogen protonation decreased electron donor properties of this fragment, and deprotonation of the hydroxyl caused the opposite effect. Substituents introduction in the phenyl fragment slightly affected hydroxyl group dissociation and nitrogen protonation.

Peculiarities of 13C NMR Spectra of Benzoylformic Acid and its Esters. 1. Benzoyl Fragment

Peculiarities of 13C NMR spectra of benzoyl fragment of benzoylformic acid and its esters have been investigated and characteristic values of a chemical shift of all five types of fragment atom have been examined. Similar parameters of other benzoyl-containing compounds by general formula Bz–X (X = H, NR2, OR, SR, Cl, Br), as well as those of compounds Bz–C (L)(M)(N) have been compared. It has been shown that spectral peculiarities of a benzoylformates phenyl fragment are defined by the carbonyl, not by the carbalkoxyl group.