The aim of the research was to determine the effectiveness of teaching
physical and health education in the fourth grade of primary school in
relation to the teachers? professional competence. The ...sample of 242
subjects, aged 10, consisted of male and female students of the fourth grade
of elementary schools in Nis, Serbia. The sample included two subsamples,
one consisting of 124 respondents who attended classes under the guidance of
physical and health education teacher (experimental group) and the other of
118 respondents who attended classes under the guidance of generalist
teacher (control group). The teaching content, intended for both groups of
students, was taught during one semester based on the physical and health
education curriculum for the fourth grade of elementary school, and the
concept of the experiment is that one group was guided by a physical and
health education teacher, and the other by a generalist teacher. The sample
of variables included six situational-motor and seven motor tests. The
abilities monitored in this paper (explosive leg strength, speed,
flexibility, balance and situational motor abilities) were tested by initial
and final testing. The results showed that there was a statistically
significant effectiveness of teaching physical and health education on the
development of motor and situational-motor abilities under the guidance of
physical and health education teacher in comparison to classes taught by
generalist teacher.
The global pandemic of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) caused many fatalities among people and significantly influenced the global economy. Since efficient treatment is ...not available, the computational methods in biology and chemistry are a promising starting point towards adequate medication. Three previously synthesized coumarin derivatives and their Pd(ii) complexes were examined for the binding affinity towards the M
protein of SARS-CoV-2 by molecular docking and compared to two Food and Drug Administration (FDA) drugs, cinanserin and chloroquine. All of the investigated compounds bind to the active position of the mentioned protein. Coumarin-Pd(ii) complexes showed higher binding affinities compared to the approved drugs. The bindings of the bis(3-(1-((3-chlorophenyl)amino)ethylidene)-chroman-2,4-dione) palladium(ii) complex, its corresponding ligand, and cinanserin to SARS-CoV-2 M
were further subjected to the molecular dynamics simulations. The binding free energies, computed by MM/PBSA approach were analyzed in detail and the importance of specific interactions outlined. These results showed that the molecules bearing structural similarity to the approved drugs and their complexes have the potential to inhibit the functional activity of SARS-CoV-2 protease and further experimental studies should be undertaken.
The aim of the research was to determine the effect of an 8-week circuit training program on explosive strength and strength endurance in physical education classes intended for high school students. ...The research included 60 students of two second-grade high school classes. Both classes attended regular physical education classes, where, within the main part of the class, one class had a special program for developing strength through circuit training (circuit group), while the other one had no modifications to the regular physical education program (control group). The classes were randomly marked as circuit group (n = 28) and control group (n = 32). Five strength tests were used in the study: squat jump, countermovement jump, squats, push-ups, and sit-ups. The results showed that the 8-week strength development program organized as circuit training contributed to a significant improvement in strength. The results of all tests showed a significant effect of training on students’ strength. It has been determined that short-term circuit training in physical education classes is an effective way to develop students’ physical performance.
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•The hydrogen atom abstraction-radical addition mechanism was examined.•The radical adduct formation followed by hydrogen atom abstraction was proposed.•The decomposition of coumarins ...induced by HO• was analyzed by EPR and DFT approach.•Rate constants of mentioned reactions were obtained by the Transition State Theory.•Ecotoxicity study showed that products were less toxic than analyzed coumarins.
The excessive use of coumarins and their derivatives is becoming an ecological concern due to their toxicity towards different organisms. One of the possible ways of their removal is the advanced oxidation processes. The oxidative breakdown of 4-hydroxycoumarin and its two derivatives, induced by a very powerful oxidizer hydroxyl radical (HO•), was investigated experimentally and theoretically. The new mechanism, namely radical adduct formation followed by hydrogen atom abstraction (RAF-HAA), was proposed. The thermodynamic parameters and rate constants, calculated by the Transition State Theory for several active positions indicated a possible reaction in which less toxic products were obtained, as confirmed by the ecotoxicity assessment. The mechanism included the reaction with two HO• and the introduction of an additional OH group to the structure. These results were compared to the more common mechanism that includes HAA between the OH group of 4-hydroxycoumarin and HO•. Based on the Quantum Theory of Atoms in Molecules and Natural Bond Orbital theory the exo-coupled electron transfer (PCET) mechanism was pointed out as a dominant pathway. Radical addiction with another HO•, followed by keto-enol tautomerism, led to the formation of the stable final product, identical to one obtained in the RAF-HAA mechanism. The reaction rates for RAF-HAA were higher then those for pure HAA and reactions were more spontaneous, therefore leading to the conclusion that the newly proposed mechanism could be a dominant pathway for the aromatic molecules’ breakdown in the advanced oxidation processes.
Ruthenium(II)-arene complexes have gained significant research interest due to their possible application in cancer therapy. In this contribution two new complexes are described, namely {RuCl(η
-
...-cymene)}
(μ-Cl)(μ-1-
,
-naphthyl)X (X = Cl,
; PF
,
), which were fully characterized by IR, NMR, and elemental microanalysis. Furthermore, the structure of
in the solid state was determined by a single crystal X-ray crystallographic study, confirming the composition of the crystals as
. The Hirshfeld surface analysis was employed for the investigation of interactions that govern the crystal structure of
. The structural data for
out of
was used for the theoretical analysis of the cationic part {RuCl(η
-
-cymene)}
(μ-Cl)(μ-1-
,
-naphthyl)
(
) which is common to both
and
. The density functional theory, at B3LYP/6-31+G(d,p) basis set for H, C, N, and Cl atoms and LanL2DZ for Ru ions, was used for the optimization of the
structure. The natural bond orbital and quantum theory of atoms in molecules analyses were employed to quantify the intramolecular interactions. The reproduction of experimental IR and NMR spectra proved the applicability of the chosen level of theory. The binding of
to bovine serum albumin was examined by spectrofluorimetry and molecular docking, with complementary results obtained. Compound
acted as a radical scavenger towards DPPH
and HO
radicals, along with high activity towards cancer prostate and colon cell lines.
The vast majority of previous studies dealing with antioxidant potency of (poly)phenols does not investigate the fate of phenoxyl radical obtained after single free radical scavenging. We ...investigated possible pathways of inactivation of ferulic acid phenoxyl radical (FAPR) using DFT method. Direct coupling with a set of 10 physiologically important free radicals, H-atom donation and dimerization were analysed by estimation of Gibbs free energy changes related to these processes. The former two processes are thermodynamically feasible to inactivate more dangerous free radicals such as hydroxyl, alkoxyl and carbon-centered radicals. Among dimerization reactions, the least energy demanding is formation of C-5−C-5 dimer of ferulic acid (FA), which has higher antiradical potency than FA itself. Obtained results reveal that FAPR, a priori considered as stable and unreactive, may contribute to the overall antioxidant activity of FA. This is a beneficial behavior, which makes FA a particularly valuable protector against oxidative stress. Hence, the contribution of phenoxyl radicals to the antioxidant activity of (poly)phenolic compounds should be taken into account, what has been scarcely considered until now.
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•The fate of ferulic acid phenoxyl radical (FAPR) was thermodynamically investigated.•The nature of scavenged free radicals influences FAPR reactivity.•FAPR may undergo coupling with free radicals, dimerization and H-atom donation.•C-5 site of FAPR is the most reactive site for radical attack.•C-5−C-5 dimer of FAPR is the most stable.
In this contribution, four new compounds synthesized from 4-hydroxycoumarin and tyramine/octopamine/norepinephrine/3-methoxytyramine are characterized spectroscopically (IR and NMR), ...chromatographically (UHPLC-DAD), and structurally at the B3LYP/6-311++G*(d,p) level of theory. The crystal structure of the 4-hydroxycoumarin-octopamine derivative was solved and used as a starting geometry for structural optimization. Along with the previously obtained 4-hydroxycoumarin-dopamine derivative, the intramolecular interactions governing the stability of these compounds were quantified by NBO and QTAIM analyses. Condensed Fukui functions and the HOMO-LUMO gap were calculated and correlated with the number and position of OH groups in the structures. In vitro cytotoxicity experiments were performed to elucidate the possible antitumor activity of the tested substances. For this purpose, four cell lines were selected, namely human colon cancer (HCT-116), human adenocarcinoma (HeLa), human breast cancer (MDA-MB-231), and healthy human lung fibroblast (MRC-5) lines. A significant selectivity towards colorectal carcinoma cells was observed. Molecular docking and molecular dynamics studies with carbonic anhydrase, a prognostic factor in several cancers, complemented the experimental results. The calculated MD binding energies coincided well with the experimental activity, and indicated 4-hydroxycoumarin-dopamine and 4-hydroxycoumarin-3-methoxytyramine as the most active compounds. The ecotoxicology assessment proved that the obtained compounds have a low impact on the daphnia, fish, and green algae population.
Thiosemicarbazones and their transition metal complexes are biologically active compounds and anticancer agents with versatile structural properties. In this contribution, the structural features and ...stability of four pyridoxal-thiosemicarbazone (PLTSC) complexes with Fe, Co, Ni, and Cu were investigated using the density functional theory and natural bond orbital approach. Special emphasis was placed on the analysis of the donor atom-metal interactions. The geometry of compounds and crystallographic structures were further examined by Hirshfeld surface analysis, and the main intermolecular interactions were outlined. It has been shown that the geometry and the number of PLTSC units in the structure determine the type and contribution of the specific interactions. The binding of all four complexes to bovine and human serum albumin was investigated through spectrofluorometric titration. The dependency of the thermodynamic parameters on the present metal ion and geometry was explained by the possible interactions through molecular docking simulations. The binding of complexes to DNA, as one of the possible ways the compounds could induce cell death, was examined by molecular docking. The cytotoxicity was measured towards HCT116, A375, MCF-7, A2780, and MCF5 cell lines, with Cu-PLTSC being the most active, as it had the highest affinity towards DNA and proteins.
Pyridoxylidene-aminoguanidine (PLAG) and its transition metal complexes are biologically active compounds with interesting properties. In this contribution, three new metal-PLAG complexes, ...Zn(PLAG)(SO4)(H2O).∙H2O (Zn-PLAG), Co(PLAG)2SO4∙2H2O (Co-PLAG), and Fe(PLAG)2SO4∙2H2O) (Fe-PLAG), were synthetized and characterized by the X-ray crystallography. The intermolecular interactions governing the stability of crystal structure were compared to those of Cu(PLAG)(NCS)2 (Cu-PLAG) within Hirshfeld surface analysis. The structures were optimized at B3LYP/6-31+G(d,p)(H,C,N,O,S)/LanL2DZ (Fe,Co,Zn,Cu), and stability was assessed through Natural Bond Orbital Theory and Quantum Theory of Atoms in Molecules. Special emphasis was put on investigating the ligand’s stability and reactivity. The binding of these compounds to Bovine and Human serum albumin was investigated by spectrofluorometric titration. The importance of complex geometry and various ligands for protein binding was shown. These results were complemented by the molecular docking study to elucidate the most important interactions. The thermodynamic parameters of the binding process were determined. The binding to DNA, as one of the main pathways in the cell death cycle, was analyzed by molecular docking. The cytotoxicity was determined towards HCT116, A375, MCF-7, and A2780 cell lines. The most active compound was Cu-PLAG due to the presence of PLAG and two thiocyanate ligands.
Coumarin derivatives have proven beneficial biological activities, but the mechanism of their radical scavenging potency is not fully understood. In this study, the antiradical capacity of two newly ...synthesized 4,7-dihydroxycoumarin derivatives: (
)-3-(1-((3-hydroxy-4-methoxyphenyl)amino)-ethylidene)-2,4-dioxochroman-7-yl acetate (
) and (
)-3-(1-((4-hydroxy-3-methoxyphenyl)amino)ethylidene)-2,4-dioxochroman-7-yl acetate (
) towards HO
were examined by Electron Paramagnetic Resonance (EPR) Spectroscopy and Density Functional Theory (DFT). The compounds were fully characterized by the elemental microanalysis, IR, and NMR spectroscopies. The effect of pH on the acid-base equilibria is separately discussed and the predominant species at the physiological pH were determined. Several common mechanisms (Hydrogen Atom Transfer (HAT), Single-Electron Transfer followed by Proton Transfer (SET-PT), Sequential Proton Loss followed by Electron Transfer (SPLET), Radical Adduct Formation (RAF), and Intramolecular Hydrogen Atom Abstraction (
HAA)) of radical scavenging were investigated based on thermodynamic and kinetic parameters. EPR results indicated that both compounds significantly reduce the amount of present HO
. The results of the kinetic DFT study demonstrated that both compounds predominantly exhibit antiradical capacity through HAT and SPLET mechanisms. The estimated overall rate constants (
) proved that
shows better antioxidant capacity than
which is well-correlated with the results obtained by EPR measurement.
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