STUDIA CHEMIA - Issue no.2 / 2017 Tom 1 - Table of contents

Transfer of thin-layer chromatography Global Pharma Health Fund Minilab kit protocols for detecting counterfeit drugs in pharmaceutical products in the field to quantitative high-performance TLC (HPTLC)-densitometry methods was carried out for potassium clavulanate and metformin HCl using a model process published earlier. HPTLC-densitometry methods were also developed following the model process for caffeine, fluoxetine HCl, and gabapentin, for which methods are not included in the Minilab manual. The model process involves use of EMD Millipore Premium Purity silica gel 60 F254 plates, automated sample and standard solution application with a CAMAG Linomat 4, and automated densitometry with a CAMAG Scanner 3 for determination of peak purity and identification and for quantification. Detection methods for counterfeit samples of the three drugs not covered in the Minilab manual were also developed and posted online with open access as supplemental methods for the Compendium of Unofficial Methods for Rapid Screening of Pharmaceuticals by Thin Layer Chromatography.

Keywords: thin layer chromatography, drug analysis, metformin HCl, potassium clavulanate, gabapentin, fluoxetine HCl, caffeine

Principal component analysis (PCA) and cluster analysis (CA) were applied to classify 20 natural amino acids. We selected 18 characteristics, properties available from literature, as a basis for the classification. The correlations between these characteristics and their classification were investigated, as well as the classification of the amino acids. The results are presented as score plots of the first 3 principal components and as dendrograms obtained by clustering analysis. The resulting classification is consistent with the chemical behavior of amino acids and their mutual substitution possibilities in peptides and proteins.

Keywords: principal component analysis, cluster analysis, amino acids, thermodynamic characteristics, structural characteristics

The enormous diversity and complexity of polysaccharides resides in the large number of anomeric positions, diversity in the size of the rings as well as of the large number of the linkage positions of the monosaccharides. By taking this fact into account, in order to provide useful knowledge for insight on polysaccharides, a more comprehensive study of the polymer units, the monosaccharides, is required. A study for relating experimentally measured properties - melting points and solubilities with other properties accessible by calculations was conducted for monosaccharides from trioses to hexoses.

Keywords: Monosaccharides; Property-property relationships; Melting points; Solubilities

Several phenolic compounds belonging to different classes were comparatively analyzed for their ability to reduce ferryl forms of three non-symbiotic phytoglobins which were generated in situ by hydrogen peroxide and thus acting as enzymes. The kinetic profiles of the substrates oxidation were evaluated using principal component analysis and cluster analysis. The three globins were different not only in terms of rate but also in mechanism and the electron donor ability of the studied phenolics were strongly enzyme specific and did not depend only upon their chemical structure but also upon assumptive binding pocket environment.

Keywords: phenolics, flavonoids, phytoglobin, reducing power

The combination of high-performance thin-layer chromatography (HPTLC) with image analysis (IA) and chemometrics becomes an attractive tool for natural extracts investigations. The large variability of these samples requires powerful image acquisition devices, multivariate image processing techniques and advanced chemometric methods to facilitate the interpretation of the chromatographic data. In the current study, two image acquisition devices and different image processing procedures were investigated using the HPTLC chromatograms of hydroalcoholic extracts of Gallium verum. Different sets of chromatographic data were generated for both UV chromatograms (obtained at 254 nm and at 366 nm) using images acquired with a digital camera and an UV-Vis TLC scanner. In all cases the Principal Component Analysis (PCA) technique was used in order to extract the information from chromatographic profiles. Variables of gray and pure colour red, green and blue intensities of pixels from start to front were used as input data in all cases. The results obtained by PCA investigations of HPTLC data from UV chromatograms at 254 nm and 366 nm respectively, provided complementary information related to the characteristics of the investigated extracts. Moreover, important steps as appropriate color scale selection and image processing/analysis procedures were pointed out based on the obtained results.

Keywords: Thin-Layer Chromatography, Image Analysis, Principal Component Analysis, Gallium verum extracts

Ileana Veche is the most representative waste rock (sterile) dump formed by the coal mining activities in Lupeni (Petroşani Basin). We developed an algorithm based on the computational engineering concepts in order to establish the connection between the waste rock soil particles composition and the dump rehabilitation by Scots Pine (Pinus sylvestris). The results show that the Ileana Veche pit coal dump features minerals suitable for plants growth like: calcite, biotite, potassium feldspar and chemically inert one as quartz. The quantitative measurements prove that the soil minerals are enough to allow a fair growing of the P. sylvestris population able to start the soil type conversion from the entiantrosoil type to a more fertile one. The measurements found that the upper soil presents humus formation and features nitrogen and phosphorous while in the deeper layer are missing.

Keywords: coal mining, coal dump, rehabilitation, mineralogy, Petroşani Basin, Romania.

In order to obtain a low crystalline nanohydrxyapatite (HAP), suitable for biomedical application, a new synthesis procedure was developed, based on the aqueous precipitation method, at room temperature, without any additives. Accordingly, lyophilized HAP powders, both calcined and non calcined, were prepared, and characterized by XRD, TEM and AFM imaging, FTIR spectroscopy, zeta potential and BET measurements. The results confirmed HAP as the only phase present. The high porosity of this nanomaterial is attained. The nanoparticle size and shape as well as the crystallinity degree of the obtained HAP samples were also determined.

Keywords: nanohydroxyapatite, chemical synthesis, XRD, TEM, AFM, FTIR, BET

The synthesis and characterization of Fe@Au and Fe@Au covered with pyrrole and pyrrole functionalized with N-succinimide is presented. The synthesis of Fe@Au nanoparticles, with diameters between 5 -7 nm was performed by the reverse micelles method. The hybrid composites Fe@Au nanoparticles covered by the pyrrole copolymer were obtained by chemical oxidative polymerization of a mixture of pyrrole and substituted pyrrole with N-succinimide monomers in water. The properties of these composites were investigated by transmission electron microscopy and FTIR spectroscopy.

Keywords: Nanoparticles; Iron; Gold; Polypyrrole; N-succinimide

Sensory evaluation is the approach currently used when evaluating the style of a South African Chenin Blanc wine. Using an untargeted LC-HRMS approach, a number of wine samples previously attributed to the three recognized styles were used to build a statistical model which was further used to predict to which style group additional samples belonged. This application can be considered proof of principle.

Keywords: Chenin Blanc wine styles; LC-MS; screening; sorting.

Artichoke (Cynara scolymus L.) is a well-known herb for its efficiency in the prevention/treatment of liver injuries, among other human chronic diseases. The aim of present study was to analyse the phytoconstituents content of aqueous and hydro-alcoholic extracts obtained from the leaves of artichoke. The chemomapping was carried out using UHPLC-ESI-MS. Several new and some known phytoconstituents were identified in the two type of extracts that have slightly different composition profiles. The newly found phytoconstituents in artichoke, plead for multiple health promoting effects that have presumably more stochastic than determinative features. Therefore, further experiments are needed using such extracts, and based on a system biology approach to clarify the complexity of beneficial effects of artichoke.

Keywords: globe artichoke, Cynara scolymus, phytoconstituents, bioactive compound, LC-ESI-MS

Fenugreek (Trigonella foenum-graecum L.) is a well-known herb for its efficiency in the prevention/treatment of diabetes among other chronic diseases. The aim of present study was to analyse the phytoconstituent profile of aqueous and hydro-alcoholic extracts of fenugreek seeds produced in Hungary. The aqueous and hydro-aqueous extracts were analysed using a UHPLC-ESI-MS approach, and in the first 54, while in the second extract 67 phytoconstituents were identified that mostly corroborate the previously described health promoting effects of fenugreek. However, it remains a huge challenge to correlate the phytoconstituent composition of the two extracts with the generated dose dependent hormetic response and cytotoxic effects that were reported by us in case of some human breast cancerous cell lines.

Keywords: fenugreek, Trigonella foenum-graecum, phytoconstituents, UHPLC-ESI-MS

The purpose of this study was the development and validation of an LC-MS/MS method, for the concomitant and rapid determination amoxicilline and clavulanic acid from human plasma. The sample workup involved a simple protein precipitation procedure. A core/shell type analytical column (50×2,1 mm, 2.6 Å) was used with PFP stationary phase. A mobile phase with high aqueous composition provided satisfactory separation with good accuracy and precision (stable ionization). The mass spectrometer was operated in positive electrospray ionization mode for both analytes and internal standard. The following parameters were evaluated for validation purpose: Selectivity, sensitivity, matrix effect, anticoagulant effect, linearity, precision and accuracy, recovery, analyte/IS stability in solvent/matrix and carryover. The validated calibration range was 190-22222 ng/ml for amoxicilline, and 147-4908 ng/ml for clavulanic acid. The correlation coefficient R2 was at least 0.99 for both analytes. The validated method has been successfully used for the evaluation bioequivalence of generic amoxicillin/potassium clavulanate formulations.

Keywords: amoxicillin, clavulanic acid, method validation, bioequivalence trial, LC-MS/MS