M. Samsonowicz

Spectroscopic study of molecular structure, antioxidant activity and biological effects of metal hydroxyflavonol complexes.

Flavonols with varied hydroxyl substitution can act as strong antioxidants. Thanks to their ability to chelate metals as well as to donate hydrogen atoms they have capacity to scavenge free radicals. Their metal complexes are often more active in comparison with free ligands. They exhibit interesting biological properties, e.g. anticancer, antiphlogistic and antibacterial. The relationship between molecular structure and their biological properties was intensively studied using spectroscopic methods (UV-Vis, IR, Raman, NMR, ESI-MS). The aim of this paper is review on spectroscopic analyses of molecular structure and biological activity of hydroxyflavonol metal complexes.

Alkali metal salts of rutin - Synthesis, spectroscopic (FT-IR, FT-Raman, UV-VIS), antioxidant and antimicrobial studies

In this work several metal salts of rutin with lithium, sodium, potassium, rubidium and cesium were synthesized. Their molecular structures were discussed on the basis of spectroscopic (FT-IR, FT-Raman, UV-VIS) studies. Optimized geometrical structure of rutin was calculated by B3LYP/6-311++G(∗∗) method and sodium salt of rutin were calculated by B3LYP/LanL2DZ method. Metal chelation change the biological properties of ligand therefore the antioxidant (FRAP and DPPH) and antimicrobial activities (toward Escherichia coli, Staphylococcus aureus, Enterococcus faecium, Proteus vulgaris, Pseudomonas aeruginosa, Klebsiella pneumonia, Candida albicans and Saccharomyces cerevisiae) of alkali metal salts were evaluated and compared with the biological properties of rutin.

Molecular structure and spectroscopic analysis of homovanillic acid and its sodium salt – NMR, FT-IR and DFT studies

The estimation of the electronic charge distribution in metal complex or salt allows to predict what kind of deformation of the electronic system of ligand would undergo during complexation. It also permits to make more precise interpretation of mechanism by which metals affect the biochemical properties of ligands. Theinfluence ofsodium cation on the electronic system of homovanillic acid was studied in this paper. Optimized geometrical structures of studied compounds were calculated by B3LYP/6-311++G(**) method. Mulliken, MK and ChelpG atomic charges were analyzed. The theoretical NMR and IR spectra were obtained. (1)H and (13)C NMR as well as FT-IR and FT-Raman spectra of studied compounds were also recorded and analyzed. The calculated parameters are compared with experimental characteristics of these molecules.

Molecular structure of phenyl- and phenoxyacetic acids – spectroscopic and theoretical study

The FT-IR, FT-Raman and (1)H and (13)C NMR spectra were recorded for phenyl- and phenoxyacetic acids in comparison with benzoic acid molecule. The density functional hybrid method (B3LYP/6-311++G(**)) was used to calculate optimized geometrical structures of studied compounds. The atomic charges were calculated by NBO (natural bond orbital) methods. Aromaticity indices, dipole moments and energies as well as the wavenumbers and intensities of IR spectra were calculated. The chemical shifts in NMR spectra using the gauge independent atomic orbital (GIAO) method were also analyzed. The theoretical parameters were compared to experimental characteristic of phenyl- and phenoxyacetic acids. The study of HOMO, LUMO and NBO analyses have been used to elucidate charge transfer within the molecule of title compounds. Molecular electrostatic potential (MEP) was also calculated.

Hydroxyflavone metal complexes - molecular structure, antioxidant activity and biological effects

High content of hydroxyflavones in fruits, vegetables, cereals and herbs makes them a common component of the human diet. Because of their antioxidant, antiviral, antibacterial, anti-inflammatory, anticancer properties they still pay an attention of many scientific centers. Hydroxyflavones may form complexes with metal cations, and their chelating properties differ significantly depending on the number and position of hydroxyl substituents in the ring. Synthesis of new complexes of hydroxyflavones allows for improvement biological properties, stability, water-solubility, hydrophilicity, bioavailability comparing with the parent hydroxyflavones. It expands the applicability of hydroxyflavones as food additives, diet supplements, preservatives or drug. This paper reviews on the procedures of synthesis of metal complexes with hydroxyflavones, their molecular structure, mode of coordinations, spectroscopic properties and their biological activity. The dependency between the biological activity of these compounds and their molecular structure is discussed.

Influence of alkaline earth metals on molecular structure of 3-nitrobenzoic acid in comparison with alkali metals effect.

The influence of beryllium, magnesium, calcium, strontium and barium cations on the electronic system of 3-nitrobenzoic acid was studied in comparison with studied earlier alkali metal ions. The vibrational FT-IR (in KBr and ATR techniques) and (1)H and (13)C NMR spectra were recorded for 3-nitrobenzoic acid and its salts. Characteristic shifts in IR and NMR spectra along 3-nitrobenzoates of divalent metal series Mg→Ba were compared with series of univalent metal Li→Cs salts. Good correlations between the wavenumbers of the vibrational bands in the IR spectra for 3-nitrobenzoates and ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy of metals were found for alkaline earth metals as well as for alkali metals. The density functional (DFT) hybrid method B3LYP with two basis sets: 6-311++G** and LANL2DZ were used to calculate optimized geometrical structures of studied compounds. The theoretical wavenumbers and intensities of IR spectra as well as chemical shifts in NMR spectra were obtained. Geometric aromaticity indices, atomic charges, dipole moments and energies were also calculated. The calculated parameters were compared to experimental characteristic of studied compounds.

Experimental and theoretical study of molecular structure of beryllium, magnesium, calcium, strontium and barium 4-nitrobenzoates.

The influence of alkaline earth metal ions on the electronic system of 4-nitrobenzoic acid was studied in this paper. The vibrational (FT-IR) and NMR ((1)H and (13)C) spectra were recorded for 4-nitrobenzoic acid (4-nba) and its salts (4-nb). The assignment of vibrational spectra was done. Some shifts of band wavenumbers in alkaline earth metal 4-nitrobenzoates spectra were observed in the series from magnesium to barium salts. Good correlations between wavenumbers of the vibrational bands in the IR spectra of studied salts and ionic potential, electronegativity, inverse of atomic mass, ionic radius and ionization energy of studied metals were found. The regular changes in the chemical shifts of protons ((1)H NMR) and carbons ((13)C NMR) in the series of studied salts were also observed. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G(**) as well as LANL2DZ basis sets. Theoretical wavenumbers and intensities in IR and chemical shifts in NMR spectra were also obtained. The calculated parameters were compared with experimental data of studied compounds.

Spectroscopic (FT-IR, Raman, NMR) and DFT Quantum Chemical Studies on Phenoxyacetic Acid and Its Sodium Salt

FT-IR, Raman, and NMR spectra of phenoxyacetic acid and its sodium salt were recorded and analyzed. Optimized geometrical structures of studied compounds were calculated by B3LYP/6-311

Evaluation of influence of selected metal cations on antioxidant activity of extracts from savory (Satureja hortensis)

The analysis of the antioxidant activity of ethanol, methanol, acetone and aqueous extracts from the dried leaves and stems of savory is presented. The culinary herb used to study was procured from ecological agriculture in the Podlasie region of Poland. The antioxidant properties of extracts were calculated using the 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) and ferric-reducing antioxidant power (FRAP) (expressed as mg Trolox per g of dry mass) methods. In addition, the total phenolics contents of the herbal extracts were determined using the Folin-Ciocalteu reagent. The antioxidative activity of extracts as dependent on the type of solvent used for the extraction and concentration of savory in extracts is discussed. The influence of the concentration of different metal ion solutions on the anti-radicals’ properties of savory extracts was evaluated.

Molecular structure of calcium, magnesium, strontium and barium m-nitrobenzoates

The effect of calcium, magnesium, strontium and barium ions on the electronic structure of m-nitrobenzoates was studied. The FT-IR spectra of m-nitrobenzoic acid and its salts were registered, assigned and analyzed. Characteristic shifts and changes in intensities of bands along the metal series were observed. The structures of m-nitrobenzoic acid and its calcium, magnesium, strontium and barium salts were optimized at the B3LYP/LANL2DZ level. Geometric aromaticity indices, atomic charges, dipole moments and energies were also calculated.