Sandra S. Konstantinović

Characterization and antimicrobial activity of the bioactive metabolites in streptomycete isolates

Twenty different streptomycete isolates were obtained from soils of southeast Serbia. Five isolates identified as Streptomyces hygroscopicus (SH100, SH101, SH102, SH103, and SH104) showed strong activity against Botrytis cinerea, a parasite found in domestic vines. These isolates were extensively studied for their in vitro antimicrobial activity against Gram-positive bacteria, Gram-negative bacteria, yeasts and fungi, and also antiviral activity against Herpes simplex. The results indicated that the obtained isolates were highly active against Botrytis cinerea, Candida albicans, and Herpes simplex, with an inhibition zone at ≥31 mm. The structure of the bioactive components was determined using elemental analysis, as well as UV/VIS, FTIR, and TLC.

Pharmacological characteristics of some 3-salicylidenehydrazono-2-indolinone coordination compounds.

Abstract3-Salicylidenehydrazono-2-indolinone (SHI) complexes with Co(II), Ni(II), Cu(II), Zn(II), and Pd(II) were synthesized. All compounds were evaluated for their antimicrobial activity against seven pathogenic bacteria and four fungi. The compounds also have been screened for anti-inflammatory activity. The complexes have better antimicrobial and anti-inflammatory than ligand itself. The in vitro antiamoebic activity was evaluated against the HM1:IMSS strain of Entamoeba histolytica, and the results were compared with the standard drug, metronidazole. The preliminary test results showed that the complexes had better antiamoebic activity than their respective ligands. SHI and its complexes were found to possess potent antioxidant activity and be better than standard antioxidants, such as vitamin C and mannitol. In particular, the Cu(II) complex displayed excellent activity on the superoxide radical.

P-Glycoprotein Polymorphism C3435T Is Associated with Dose-Adjusted Clopidogrel and 2-Oxo-Clopidogrel Concentration

Background/Aims: One of the most common polymorphisms of ABCB1 gene, a synonymous mutation C3435T (rs1045642), is associated with increased in vivo activity. The main goal of this study was to determine the association of C3435T polymorphism with clopidogrel and 2-oxo-clopidogrel concentrations in plasma. Methods: The patients were recruited upon acute myocardial infarction diagnosis. They were all tested for ABCB1 C3435T polymorphism. In plasma, drawn 1 h after the drug administration, concentrations of clopidogrel and 2-oxo-clopidogrel were measured using UHPLC-DAD-MS analysis. Results: Due to differences in the maintenance doses, we have calculated the dose-adjusted concentrations of clopidogrel (0.2 ng/ml/mg (0.1-0.4)) and 2-oxo-clopidogrel (2.1 ng/ml/mg (0.5-4.6)). Patients carrying at least one C allele achieved significantly higher serum concentration of clopidogrel (p < 0.001), as well as dose-adjusted clopidogrel (p < 0.001) and 2-oxo-clopidogrel concentrations (p < 0.05). Conclusion: The ABCB1 3435CC genotype is associated with increased clopidogrel and 2-oxo-clopidogrel dose-adjusted concentrations. Therefore, the ABCB1 C3435T genotyping should be one of the parameters taken into account when deciding about the dosing regimen of clopidogrel.

Radiation stability of nanosilica-based urea–formaldehyde composite materials:

Three types of nanosilica-based urea–formaldehyde (UF) hybrid composite materials with a formaldehyde-to-urea (F/U) ratio of 0.8 were synthesized (UF with SiO2—Resin 1, UF + SiO2 + thiourea [TU]—Resin 2 and UF + SiO2 + thiosemicarbazide [TSC]—Resin 3). The thermal behavior of obtained materials was studied by nonisothermal thermogravimetric analysis (TGA), differential thermal gravimetry (DTG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC) and supported by data from Fourier transform infrared spectroscopy (FTIR). Nanosilica-based UF hybrid composites have been irradiated (50 kGy) and after that their radiation stability was evaluated on the basis of thermal behavior. The percentage of free formaldehyde in all prepared samples was determined. DTG peaks of unmodified nanosilica-based UF resin (UF with SiO2) are shifted to a high temperature. The minimum percentage values of free formaldehyde (3%) for samples based on UF with SiO2 and UF + SiO2 + TSC after irradiation dose of 50 kGy are detected.

SYNTHESIS AND STRUCTURE OF VANILLIN AZOMETHINES

Vanillin is most prominent as the principal flavor and aroma compound in vanilla. Vanillin has been used as a chemical intermediate in the production of pharmaceuticals and other fine chemicals. The two intermediates, assigned as intermediates I and II, were prepared by using vanillin and 1-butylbromide or 2-chloroacetic acid, respectively. The condensation of intermediates with 2,3-diaminopyridine gave azomethines. Their structure was established by using elemental microanalysis, as well as UV/Vis, FTIR and 1H-NMR spectra. Synthesized compounds were tested for their antifungal activity against Candida albicans, Candida lipolytica and Sacharomyces cerevisiae.

The physicochemical and thermodynamic properties of the choline chloride-based deep eutectic solvents

This paper reports the physical (density, dynamic viscosity, electrical conductivity and refractive index) and thermodynamic (thermal expansion coefficient, molecular volume, lattice energy and heat capacity) properties of choline chloride (ChCl):propylene glycol, ChCl : 1,3-dimethylurea and ChCl : thiourea deep eutectic solvents (DESs) (1:2 molar ratio) at atmospheric pressure as a function of temperature over the range of 293.15-363.15 K. Their properties were also compared with those of some already characterized ChCl-based DESs, namely ChCl:ethylene glycol, ChCl:glycerol and ChCl : urea (1:2 molar ratio). Density, viscosity and refractive index of all DESs decrease with increasing temperature while electrical conductivity increases. Viscosity and conductivity of the tested DESs were fitted by both Arrhenius and Vogel-Tamman-Fulcher equations. The molar enthalpy, entropy and Gibbs energy of activation, determined using the Eyring theory, demonstrates the interactional factor as predominant over the structural factor for all DES systems. The fractional Walden rule, used to correlate molar conductivity and viscosity, showed an excellent linear behavior. It was shown that ChCl:propylene glycol DES had properties similar to ChCl:ethylene glycol and ChCl:glycerol DESs. However, the properties ( density, viscosity and electrical conductivity ) of ChCl : 1,3-dimethylurea and ChCl : thiourea DESs were inferior to those of the ChCl : urea DES.

Spectroscopic and thermodynamic studies of complexation of some divalent metal ions with isatin-β-thiosemicarbazone

Metal complexes of some divalent metal ions (Co, Ni, Cu, Zn, Hg, and Pd) with isatin-β-thiosemicarbazone (ITS) as the Schiff base have been investigated potentiometrically and spectrophotometrically. The dissociation constants of the ligand and formation constants of the metal complexes, as well as the corresponding thermodynamic functions (ΔG, ΔH and ΔS) have been determined at different temperatures in ethanol—water solution. The full stability constants were also evaluated spectrophotometrically by the Job method. The experimental results indicate that Cu(II), Zn(II), Pd(II), and Hg(II) form one-to-one molecular complexes (ML) with the studied ligand, whereas Co(II) and Ni(II) form both ML and ML2 species.

Decolorization of model wastewater by adsorbent obtained from waste hemp fibers

Water pollution has already become a significant worldwide problem, especially in the textile dyeing industry. This paper describes decolorization of dye water modelled by textile dye wastewater. Decolorization was performed on an adsorbent made from physicochemically modified waste hemp fibers, obtained as a by-product from the production of ropes. The adsorbent is relatively dispersive and contains heterogeneous porous particles, with carbon as a dominant element. Obtained results have shown that the positive effect of adsorption directly depends on contact time, pH, temperature, and initial dye concentration. Dye concentration decreases in time, especially when the used concentration is the initial one. The effect of temperature below 40 °C is not significant, but adsorption gets more intensive when performed at 60 °C. The higher degree of decolorization is achieved at lower initial dye concentrations, although the highest initial dye concentration leads to higher dye adsorption. The experimental results of adsorption were described by using the Langmuir model. The maximum adsorption capacity ranges from 1.98 to 2.13 mg g for linear and 2.03 to 2.12 mg g for nonlinear form.

The use of salicylaldehyde derivatives as a nitrogen source for antibiotic production by Streptomyces hygroscopicus CH-7

In the present work, four derivatives of salicylaldehyde (salicylaldehyde-hydrazone, phenylhydrazone, semicarbazone and thiosemicarbazone) were synthesized using both conventional (95% ethanol) and green (crude glycerol from biodiesel production) solvents. The obtained compounds were identified by elemental microanalysis, as well as FTIR, UV/VIS, 1H NMR and X-ray spectroscopic methods. Yields of 93-98% of the compounds in crude glycerol were achieved within 10-25 min. The derivatives of salicylaldehyde and crude glycerol were used as a nitrogen and carbon source, respectively, in the medium for antibiotic (Hexaene H-85 and Azalomycine B) production by Streptomyces hygroscopicus CH-7. The highest concentrations of Hexaene H-85 and Azalomycine B were achieved in the medium containing salicylaldehyde-thiosemicarbazone (198 g/cm3 and 69 µg/cm3, respectively). Derivatives of salicylaldehyde also impacted the strain morphology. In the media with salicylaldehyde-phenylhydrazone and salicylaldehyde-thiosemicarbazone, S. hygroscopicus CH-7 grew like large dispersive pellets with long twisted filaments that produced the highest yield of the antibiotics.

The Influence of Modified Media with Carboxymethyl Cellulose on Morphology and Antibiotic Production by Streptomyces Hygroscopicus

ABSTRACT Actinomycetes, especially members of the genus Streptomyces, are responsible for producing the majority of known antibiotics. The production of antibiotics by filamentous organisms is often dependent on the morphology and size distribution of the pellet population within the culture. The effect of carboxymethylcellulose (CMC) on growth and antibiotic (hexaene and azalomycine) production by Strepotmyces hygroscopicus were investigated. By adding the polymer to the fermentation medium, the growth was changed from a single large glob to small reproducible pellets, and wall growth was diminished to a minimum. Maximum concentration of hexaene was reached at 3% (wt/vol) CMC and maximum concentration of azalomycine was reached at 1 % (wt/vol) CMC.