Molecular structure and microbiological activity of alkali metal 3,4-dihydroxyphenylacetates

DFT Study of Some Copper Complexes and Their Detection Limit

A theoretical investigation was probed to shed light on the correlation between low detection limit (LOD) in AdSV technique and metal trace complexes stability energy. The study was conducted by means of DFT calculations of copper traces complexation by using three different organic molecules as chelating agents, such as: morin, red pyrogallol and thymolphtalexone. The quantum chemistry calculations were carried out at the B3LYP/6-31G(d) level implemented in Gaussian 09 program package. The results of the electrophilicity index ω indicate that all the studied molecules have a tendency to exchange electron with copper. The negative values of free energy G and enthalpy H show that the complexation reactions are spontaneous in nature and exothermic. According to DFT calculations, copper-red pyrogallol complex with better detection limit (0.07 ng•mL-1) has the lowest total energy (-5100.213 a.u.). Thus, there is a very strong relationship between the total energy of the three complexes and their detection limits in AdSV technique. Hence, the more stable complex has the better detection limit value.

Spectroscopic, Thermal, Microbiological, and Antioxidant Study of Alkali Metal 2-Hydroxyphenylacetates

The structural, spectral, thermal, and biological properties of hydroxyphenylacetic acid and lithium, sodium, potassium, rubidium, and cesium 2-hydroxyphenylacetates were analyzed by means of infrared spectroscopy FT-IR, electronic absorption spectroscopy UV-VIS, nuclear magnetic resonance ¹H and ¹³C NMR, thermogravimetric analysis (TG/DSC), and quantum-chemical calculations at B3LYP/6-311++G** level. Moreover, the antioxidant (ABTS, FRAP, and CUPRAC assays), antibacterial (against E. coli, K. aerogenes, P. fluorescens, and B. subtilis) and antifungal (against C. albicans) properties of studied compounds were measured. The effect of alkali metal ions on the structure, thermal, and biological properties of 2-hydroxyphenylacetates was discussed.

Interaction between favipiravir and hydroxychloroquine and their combined drug assessment: in silico investigations

Hydroxychloroquine (HCQ) and favipiravir (FPV) are known to be effective antivirals, and there are reports about their use to fight the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) despite that these are not conclusive. The use of combined drugs is common in drug discovery, and thus, we investigated HCQ and FPV as a combined drug. The density functional theory method was used for the optimization of geometries, spectroscopic analysis and calculation of reactivity parameters. The quantum theory of atoms in molecules was applied to explain the nature of the hydrogen bonds and confirm the higher stability of the combined drug. We also evaluated the absorption, distribution, metabolism and excretion (ADME) parameters to assess their drug actions jointly using SwissADME. The preliminary findings of our theoretical study are promising for further investigations of more potent and selective antiviral drugs.

Molecular Structure and Antioxidant Properties of Alkali Metal Salts of Rosmarinic Acid. Experimental and DFT Studies

The molecular structure of alkali metal rosmarinates was studied in comparison to rosmarinic acid using FT-IR, FT-Raman, 1H and 13C NMR spectroscopy, as well as density functional theory (DFT) calculations. The B3LYP/6-311+G(d,p) method was used to calculate optimized geometrical structures of studied compounds, atomic charges, dipole moments, energies, as well as the wavenumbers and intensities of the bands in vibrational and NMR spectra. Theoretical parameters were compared to experimental data. Antioxidant activity was determined using two spectrophotometric methods: (i) Assessing the ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable radical and (ii) assay of antioxidant power of ferric ions reducing (FRAP). The linear correlations were found between HOMO-LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) energy gap and the reducing power expressed as FRAP (R = 0.77) as well as between IC50 values (the ability of quenching DPPH radicals) and Δνas-s(COO) in IR spectra (differences between asymmetric and symmetric stretching vibrations bands) (R = 0.99). Photochemical properties of studied compounds were also evaluated. The influence of alkali metal on the electronic system of the rosmarinic acid molecule was discussed.

Antioxidant properties of coffee substitutes rich in polyphenols and minerals

The analysis of general content of polyphenols, minerals and antioxidant activity of infusions from selected coffee substitutes is presented. The obtained results showed that the coffee infusions prepared from acorns exhibit the highest radical scavenging capacities for DPPH (EC₅₀ = 0.063-0.066 mg_d.w./mL), ABTS (EC₅₀ = 0.021-0.029 mg_d.w./mL), OH(EC₅₀ = 2.050-2.378 mg_d.w./mL) as well as the highest ability to Fe³⁺ reduction (FRAP) (∼1.1 mmolFe/g_d.w). These coffee substitutes also contain the greatest values of polyphenols (45-50 mgGA/g_d.w). Analyzed coffee substitutes differ in both quality and quantity of polyphenols, but all tested coffees contain gallic and chlorogenic acids. The most of phenolic compounds was found in herbal-cereal coffee substitute. The quantitative results and PCA analysis indicated a good correlation between the antioxidant activity and total polyphenols, flavonoids and gallic acid content. Using the obtained data on the composition and antioxidant properties of extracts the cluster analysis (CA) was performed to distinguish similar or close types of coffee.