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  • Author: Verica Vasić x
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Summary

The aim of this research was to investigate the microbial activity in forest soil from different sites under deciduous and coniferous trees in Serbia. One site on Stara planina was under beech trees (Fagus sp.) while another under mixture of spruce (Picea sp.) and Douglas fir (Pseudotsuga sp.). The site on Kopaonik was under mixture of beech (Fagus sp.) and spruce (Picea sp.) trees. The site on Tara was dominantly under fir (Abies sp.), beech (Fagus sp.) and spruce (Picea sp.). The total number of bacteria, the number of actinobacteria, fungi and microorganisms involved in N and C cycles were determined using standard method of agar plates. The activities of dehydrogenase and ß-glucosidase enzymes were measured by spectrophotometric methods. The microbial activity was affected by tree species and sampling time. The highest dehydrogenase activity, total number of bacteria, number of actinobacteria, aminoheterotrophs, amylolytic and cellulolytic microorganisms were determined in soil under beech trees. The highest total number of fungi and number of pectinolytic microorganisms were determined in soil under spruce and Douglas fir trees. The correlation analyses proved the existence of statistically significant interdependency among investigated parameters.

Abstract

New zinc(II)-complexes with S-alkyl derivatives of thiosalicylic acid (alkyl = benzyl-(L1), methyl-(L2), ethyl-(L3), propyl-(L4), butyl-(L5)) have been synthesized and characterized by elemental microanalysis, IR spectroscopy, and 1H and 13C NMR spectroscopy. The S-alkyl derivatives of thiosalicylic acid were prepared by alkylation of thiosalicylic acid by adding alkyl halides to an alkaline water-ethanol solution, while the corresponding zinc(II)-complexes were obtained via the direct reaction of ZnCl2 with S-alkyl derivatives of thiosalicylic acid in water. Based on the microanalysis results and the IR and NMR spectra of the S-alkyl derivatives of thiosalicylic acid and the corresponding zinc(II)-complexes, we concluded that the ligands are bidentately coordinated to the zinc(II)-ion.

Abstract

New complexes of copper(II) with S-alkenyl derivatives of thiosalicylic acid (alkenyl = propenyl-(L1), isobutenyl-(L2)) have been synthesized and characterized by microanalysis, infrared spectra, magnetic measurements, and by NMR spectra. The cytotoxic activity of two newly synthesized precursor S-alkenyl derivatives of thiosalicylic acid were tested using an MTT colorimetric technique on HCT-116 human colon carcinoma cells. The cytotoxic effect of the copper(II)- complexes were higher compared to the cytotoxicity of the corresponding ligand (for concentrations from 31.25 to 250 μM). Copper(II)-complexes showed a slightly lower cytotoxicity compared to cisplatin. Complexes of copper(II) with S-alkenyl derivatives of thiosalicylic acid (at concentrations from 250 to 1000 μM) had a cytotoxic effect on HCT-116 cells compared to cisplatin.

Abstract

New platinum(IV)-complexes with S-alkyl derivatives of thiosalicylic acid (alkyl = benzyl-(L1), methyl-(L2), ethyl-(L3), propyl-(L4), butyl-(L5)) have been synthesized and characterized by microanalysis, infrared spectroscopy, and 1H and 13C NMR spectroscopy. Th e bidentate S,O ligand precursor, the S-butyl derivative of thiosalicylic acid (S-bu-thiosal), was prepared, and its crystal structure was determined. Single crystals suitable for X-ray measurements were obtained by slow crystallization from a DMSO-water system. S-bu-thiosal crystallized in a P21/c space group of a monoclinic crystal system with a = 8.0732 (3) Å, b = 19.6769 (4) Å, c = 8.2291 (3) Å and Z = 4. S-bu-thiosal also has a coplanar geometry.