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Novi Beograd, Serbia

Kundakovic T.,University of Belgrade | Milenkovic M.,University of Belgrade | Zlatkovic S.,Actavis Trading Ltd | Kovacevic N.,University of Belgrade | Goranc N.,University of Nis
Natural Product Communications

The composition of the essential oil obtained by hydrodistillation from the aerial parts of Satureja kitaibelii from Rtanj mountain (Serbia), collected during three years, was studied. Thirty-nine components were identified in each sample of S. kitaibelii essential oil, representing about 87% of the oils. p-Cymene was the most dominant compound in all three oils (27.9%, 14.7% and 24.4%, respectively). The simple formulation of a lozenge with 0.2% of S. kitaibelii essential oil was prepared and the antimicrobial activity of the essential oil and the lozenge with essential oil was tested using a broth microdilution assay. Both essential oil and lozenge possessed strong antimicrobial activity with MIC values of 0.10-25 μg/mL, and 0.97-15.6 mg/mL, respectively. Source

Nikolic V.,University of Nis | Stankovic M.,University of Nis | Nikolic L.,University of Nis | Nikolic G.,University of Nis | And 4 more authors.
Journal of Inclusion Phenomena and Macrocyclic Chemistry

Molecular inclusion complexes of usnic acid (UA) with β-cyclodextrin (β-CD) and 2-hydroxypropyl β-cyclodextrin (HP β-CD) were prepared by the co-precipitation method in the solid state in the molar ratio of 1:1. Structural complexes characterization was based on different methods, FTIR, 1H NMR, XRD and DSC. Parallel to the complex by the above methods, corresponding physical mixtures of UA with cyclodextrins and complexing agents (β-CD, HP β-CD and UA) were analyzed. The results of DSC analysis showed that, at around 200 C, the endothermal peak in the complexes with cyclodextrins originating from the UA melting has disappeared. Complex diffractogram patterns do not contain peaks characteristic for the pure UA. They are more appropriate to cyclodextrin diffractogram. This fact points to the molecular encapsulation of UA in the cyclodextrin cavity. Chemical shifts in 1H NMR spectra after the inclusion of UA into the cyclodextrin cavity, especially H-3 protons (0.0012 and 0.0102 ppm in the β-CD and HP β-CD, respectively) and H-5 and H-6 (0.0134 ppm) and hydrogen from CH 3 (0.0073 ppm) HP β-CD also points to the formation of molecular inclusion complexes. The improved solubility of UA in water was achieved by molecular incapsulation. In the complex with β-CD the solubility is 0.3 mg/cm3, with HP β-CD 4.2 mg/cm3 while the uncomplexed UA solubility is 0.06 mg/cm3. The microbial activity of UA and both complexes was tested against eight bacteria and two fungi and during the test no reduced activity of UA in the complexes was observed. © 2012 Springer Science+Business Media B.V. Source

Savic I.,University of Nis | Nikolic G.,University of Nis | Zlatkovic S.,Actavis Trading Ltd | Djokic D.,PCI Zdravlje Actavis
Macedonian Journal of Chemistry and Chemical Engineering

New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were developed and validated for the estimation of sodium usnate in pharmaceutical preparations. Sodium usnate was estimated at 290 nm in water and phosphate buffer (pH 3):methanol (11:20 V/V). Beer's law was obeyed in the concentration range of 0.1-5 μg·cm-3 (r = 0.997) in water and 1-12 μg·cm-3 (r = 0.999) in the phosphate buffer:methanol. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 3.16×104 dm3·mol-1·cm-1 and 11.58 ng·cm-2/0.001 A in water and 3.72×104 dm3·mol-1·cm-1 and 9.83 ng·cm-2/0.001 A in phosphate buffer:methanol, respectively, indicating the high sensitivity of the proposed methods. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.0721 and 0.2163 μg·cm-3 in water and 0.163, 0.489 μg·cm-3 in phosphate buffer:methanol, respectively. The proposed methods were successfully applied for the determination of sodium usnate in pharmaceutical preparations. The results demonstrated that the procedure is accurate, precise and reproducible (R.S.D. < 2 %). Source

Zlatkovic S.Z.,Actavis Trading Ltd
Journal of Medicinal Plants Research

The present study is aimed at investigating the effects of variation in secondary metabolites of St. John's wort for its better use as an antibiotic. The seasonal dynamics investigation of St. John's wort secondary metabolites was carried out on annual, biennial and triennial wild-growing plants of the suburban localities, and on the indigenous perennial plants of the mountainous localities. The effects of variation in secondary metabolites of the plant material were monitored using a complex antimicrobial preparation imanin. As plant secondary metabolites, imanin was isolated from flowers and leaves of St. John's wort by aqueous-alkaline extraction. The quality of imanin contained in St. John's wort was determined by FTIR and HPLC methods. The imanin extracts were tested for antimicrobial activity against Staphylococcus aureus, Streptococcus agalactiae, Bacillus diphteriae, Bacillus tetani, Clostridium histolyticus, Bacillus mesentericus and Bacillus mycoides. The quantitative effects of temperature and light intensity on imanin accumulations in St. John's wort were examined depending on the sampling periods and location. The results of antimicrobial activity and quantitative effects of climatic conditions were correlated with vegetation phases of hypericum plants. © 2010 Academic Journals. Source

Nikolic G.,University of Nis | Zlatkovic S.,Actavis Trading Ltd | Cakic M.,University of Nis | Cakic S.,University of Nis | And 2 more authors.

The use of fast FT-IR spectroscopy as a sensitive method to estimate a change of the crosslinking kinetics of epoxy resin with polyamine adducts is described in this study. A new epoxy formulation based on the use of polyamine adducts as the hardeners was analyzed. Crosslinking reactions of the different stoichiometric mixtures of the unmodified GY250 epoxy resin with the aliphatic EH606 and the cycloaliphatic EH637 polyamine adducts were studied using mid FT-IR spectroscopic techniques. As the crosslinking proceeded, the primary amine groups in polyamine adduct are converted to secondary and the tertiary amines. The decrease in the IR band intensity of epoxy groups at about 915 cm-1, as well as at about 3,056 cm-1, was observed due to process. Mid IR spectral analysis was used to calculate the content of the epoxy groups as a function of crosslinking time and the crosslinking degree of resin. The amount of all the epoxy species was estimated from IR spectra to changes during the crosslinking kinetics of epichlorhydrin. © 2010 by the authors. Source

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