Katarzyna Paradowska

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Oxindole alkaloids, isolated from the bark of Uncaria tomentosa [Willd. ex Schult.] Rubiaceae, are considered to be responsible for the biological activity of this herb. Five pentacyclic and two tetracyclic alkaloids were studied by solid-state NMR and theoretical GIAO DFT methods. The (13)C and (15)N CPMAS NMR spectra were recorded for mitraphylline,(More)
BACKGROUND Herbhoneys, relatively new bee products, are expected to have interesting medicinal properties. However, there is still a lack of data concerning their composition and antioxidant properties. ¹H and ¹³C NMR spectroscopy coupled with chemometric analysis (PCA and PLS-DA) and antioxidant assays (DPPH-ESR and ORAC-FL) were used to study 25 samples(More)
There is a wide diversity of plants and seasonal crops in Peru, due to the presence of many climatic zones. Numerous plants are used to cure or prevent diseases. These plants are promising candidates for functional foods products. The most frequent form in which they are used is an aqueous infusion or decoction. In this study, we compared the antioxidant(More)
13C CPMAS NMR spectra of dietary fiber powders from aronia (chokeberry), bilberry, black currant and apple were recorded. The spectra are complex owing to superposition of resonances from different polysaccharides and polyphenolic compounds. Standard, dipolar dephased and the TH(1rho) partially relaxed spectra enabled the identification of several(More)
13C cross-polarization magic-angle spinning NMR spectra were recorded for a series of solid coumarins. Ab initio calculations of shielding constants were performed with the use of GIAO-CHF method. The combined CPMAS NMR and theoretical approach was successful in characterizing solid-state conformations of coumarins; a relationship sigma (ppm) = -1.032(More)
This paper presents a preliminary study in building discriminant models from solid-state NMR spectrometry data to detect the presence of acetaminophen in over-the-counter pharmaceutical formulations. The dataset, containing 11 spectra of pure substances and 21 spectra of various formulations, was processed by partial least squares discriminant analysis(More)
This article presents some of the solid-state NMR (SSNMR) techniques used in the pharmaceutical and biomedical research. Solid-state magic angle spinning (MAS) NMR provides structural information on powder amorphous solids for which single-crystal diffraction structures cannot be obtained. NMR is non-destructive; the powder sample may be used for further(More)
Quercetin (Q) as a pentahydroxy flavonoid, has three possible chelating sites competing in complexation processes. (1)H and (13)C MAS NMR spectra were recorded for solid quercetin and its Al(III) complex (AlQ). (1)H MAS spectrum of quercetin shows a broad resonance at ca. 12 ppm that confirms the existence of intramolecular C5-OH … O=C4 hydrogen bond. Such(More)
The X-ray diffraction analysis of N-o-nitrophenyl-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosylamine (1), N-m-nitrophenyl-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosylamines, N-p-nitrophenyl-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosylamines, and their N-acetyl derivatives was performed. The sugar moieties always adopt (4)C1 conformations, however, due to(More)
The X-ray diffraction analysis of o-nitrophenyl 2,3,4,6-tetra-O-acetyl-beta-D-galactopyranoside (1), m-nitrophenyl 2,3,4,6-tetra-O-acetyl-beta-D-galactopyranoside, p-nitrophenyl 2,3,4,6-tetra-O-acetyl-beta-D-galactopyranoside and o-nitrophenyl 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside was performed. It was found that except in the case of 1, all other(More)