Synthesis and Characterization of 3-(1-((3,4-Dihydroxyphenethyl)amino)ethylidene)-chroman-2,4-dione as a Potential Antitumor Agent

The newly synthesized coumarin derivative with dopamine, 3-(1-((3,4-dihydroxyphenethyDamino)ethylidene)-chroman-2,4-dione, was completely structurally characterized by X-ray crystallography. It was shown that several types of hydrogen bonds are present, which additionally stabilize the structure. The compound was tested in vitro against different cell lines, healthy human keratinocyte HaCaT, cervical squamous cell carcinoma SiHa, breast carcinoma MCF7, and hepatocellular carcinoma HepG2. Compared to control, the new derivate showed a stronger effect on both healthy and carcinoma cell lines, with the most prominent effect on the breast carcinoma MCF7 cell line. The molecular docking study, obtained for ten different conformations of the new compound, showed its inhibitory nature against CDKS protein. Lower inhibition constant, relative to one of 4-OH-coumarine, proved stronger and more numerous interactions with CDKS protein. These interactions were carefully examined for both parent molecule and derivative and explained from a structural point of view

Green One-Pot Synthesis of Coumarin-Hydroxybenzohydrazide Hybrids and Their Antioxidant Potency

Compounds from the plant world that possess antioxidant abilities are of special importance for the food and pharmaceutical industry. Coumarins are a large, widely distributed group of natural compounds, usually found in plants, often with good antioxidant capacity. The coumarin-hydroxybenzohydrazide derivatives were synthesized using a green, one-pot protocol. This procedure includes the use of an environmentally benign mixture (vinegar and ethanol) as a catalyst and solvent, as well as very easy isolation of the desired products. The obtained compounds were structurally characterized by IR and NMR spectroscopy. The purity of all compounds was determined by HPLC and by elemental microanalysis. In addition, these compounds were evaluated for their in vitro antioxidant activity. Mechanisms of antioxidative activity were theoretically investigated by the density functional theory approach and the calculated values of various thermodynamic parameters, such as bond dissociation enthalpy, proton affinity, frontier molecular orbitals, and ionization potential. In silico calculations indicated that hydrogen atom transfer and sequential proton loss–electron transfer reaction mechanisms are probable, in non-polar and polar solvents respectively. Additionally, it was found that the single- electron transfer followed by proton transfer was not an operative mechanism in either solvent. The conducted tests indicate the excellent antioxidant activity, as well as the low potential toxicity, of the investigated compounds, which makes them good candidates for potential use in food chemistry

Biosynthesis and characterization of silver nanoparticles synthesized using extracts of Agrimonia eupatoria L. and in vitro and in vivo studies of potential medicinal applications

This research explores the synthesis, characterization, and biological activities of silver nanoparticles (AgNPs) derived from acetone (AgNPs-acetone) and aqueous (AgNPs-H2O) extracts of Agrimonia eupatoria. The nanoparticles exhibit isometric morphology and uniform size distribution, as elucidated through Transmission Electron Microscopy (TEM) and high-resolution TEM (HRTEM) analyses. The utilization of Scanning Transmission Microscopy (STEM) with High-Angle Annular Dark-Field (HAADF) imaging and energy dispersive spectrometry (EDS) confirms the crystalline nature of AgNPs. Fourier Transform Infrared (FTIR) analysis reveals identical functional groups in the plant extracts and their corresponding AgNPs, suggesting the involvement of phytochemicals in the reduction of silver ions. Spectrophotometric monitoring of the synthesis process, influenced by various parameters, provides insights into the kinetics and optimal conditions for AgNP formation. The antioxidant activities of the plant extracts and synthesized AgNPs are evaluated through DPPH and ABTS methods, highlighting AgNPs-acetone as a potent antioxidant. Third-instar larvae exposed to the extracts have differential effects on DNA damage, with the acetone extract demonstrating antigenotoxic properties. Similarly, biosynthesized AgNPs-acetone displays antigenotoxic effects against EMS-induced DNA damage. The genotoxic effect of water extract and AgNPs-acetone was dose-dependent. Hemolytic potential is assessed on rat erythrocytes, revealing that low concentrations of AgNPs-acetone and AgNPs-H2O had a nontoxic effect on erythrocytes. Cytotoxicity assays demonstrate time-dependent and dose-dependent effects, with AgNPs-acetone exhibiting superior cytotoxicity. Proapoptotic activity is confirmed through apoptosis induction, emphasizing the potential therapeutic applications of AgNPs. The antimicrobial activity of AgNPs reveals concentration-dependent effects. AgNPs-H2O display better antibacterial activity, while antifungal activities are comparable between the two nanoparticle types

The interaction of protonated octopamine and norepinephrine with β1-adrenergic receptor: Molecular docking and dynamical simulation

© 2020, Serbian Society of Computational Mechanics. In the current study, the interaction mechanisms between protonated neurotransmitters: octopamine (4-(2-amino-1-hydroxyethyl)phenol) and norepinephrine (4-[(1R)-2-amino-1-hydroxyethyl]benzene-1,2-diol) with the β-1 adrenergic receptor (β1AR) were examined by molecular docking, molecular dynamics (MD) simulations and MM/PBSA free energy calculations. The investigated receptor belongs to the G-protein coupled receptor group. The investigation was carried out at physiological pH=7.4. It was estimated that both compounds exist in the protonated form in the water at physiological pH. It was found that both protonated neurotransmitters established similar interactions with amino acid residues of the receptor, such as salt bridges, conventional hydrogen bonds, π-σ, and T-shaped π-π interactions, as shown by molecular docking simulations. As the initial structures for MD simulation with a total time of 10ns the most stable docking structures were used. The presented results are expected to provide some useful information for the design of specific β1AR agonists

Native Mesorhizobium strains improve yield and nutrient composition of the common bird's-foot trefoil grown in an acid soil

10 Pág.Acid soils occupy more than 3.95 billion ha of the world soils, and finding an adequate solution for the limitation of crop production on these soils is indispensable. Using highly effective rhizobia tolerant to low pH enables successful nodulation and quality crop production of legumes in acid soils. In this study, isolation and characterization of native rhizobia associated with root nodules of bird's-foot trefoil (Lotus corniculatus L.) from Serbia were conducted. Their effects on the plant yield and nutrient composition of bird's-foot trefoil grown in an acid soil (pH 5.4), in a pot experiment were evaluated. Out of 72 strains isolated, 40 could nodulate bird's-foot trefoil when reinoculated in the test tubes under gnotobiotic conditions, and 23 isolates showed high nitrogen-fixing efficiency. Overall, all isolates could grow well in medium with a pH between 4.5 and 8. Indole-3-acetic acid (IAA) production was detected in all nodulating isolates and 24 could solubilize inorganic phosphates. The identification of selected isolates showed that all belong to Mesorhizobium genus (M. tianshanense, M. erdmanii, M. cantuariense, M. loti, M. jarvisii and M. caraganae). Four acid-tolerant isolates (1M12, 631oz, U1C, and 754) with high nitrogen-fixing efficiency in vitro and particular PGP traits were selected for the pot experiment with acid soil. All applied bacterial treatments (except 1M12) increased the shoot dry weight of bird's-foot trefoil plants (up to 50%), compared to the control. In addition, N uptake and N% were increased up to 20% by inoculation. All applied treatments influenced the concentrations and improved uptake of macro (P, K, Ca, and Mg) and micronutrients (Cu, Fe, Mn, Ni, Zn, and B) in the plant material. The obtained results indicated that satisfactory yield and mineral composition of L. corniculatus in acid soils could be achieved by inoculation with selected Mesorhizobium strains.This research was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia, under the contract numbers 451-03-9/2021-14/200011 and 451-03-9/2021-14/200178.Peer reviewe

Inhibitory activity of quercetin, its metabolite, and standard antiviral drugs towards enzymes essential for SARS-CoV-2: The role of acid-base equilibria

© 2021 The Royal Society of Chemistry. The recently declared global pandemic of a new human coronavirus called SARS-CoV-2, which causes respiratory tract disease COVID-19, has reached worldwide resonance and global efforts are being made to look for possible cures. Sophisticated molecular docking software, as well as available protein sequence and structure information, offer the ability to test the inhibition of two important targets of SARS-CoV-2, furin (FUR) enzyme, and spike glycoprotein, or spike protein (SP), that are key to host cell adhesion and hijacking. The potential inhibitory effect and mechanism of action of acid-base forms of different antiviral drugs, dominant at physiological pH, chloroquine (CQ), hydroxychloroquine (HCQ), and cinanserin (CIN), which have been shown to be effective in the treatment of SARS-CoV-2 virus, is reported with the special emphasis on their relative abundances. On the other hand, the potential inhibitory effect of the dominant acid-base forms of quercetin (Q) and its oxidative metabolite 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H) benzofuranone (BZF), which are constituents of traditional food products believed to exhibit antiviral effects, was also examined. The undertaken study includes the determination of the major energy contributions to the binding energy as well as in-depth analysis of amino acid residues at the active pocket and possible interactions. The approach that we propose here may be an additional strategy for combating the deadly virus by preventing the first step of the virus replication cycle. Preliminary research has shown that the investigated compounds exert an inhibitory effect against the SARS-CoV-2 furin enzyme and spiked glycoprotein through different acid-base forms. These investigations may be helpful in creating potential therapeutic agents in the fight against the SARS-CoV-2 virus. On the other hand, the results we predicted in this computational study may be the basis for new experimental in vitro and in vivo studies. This journal i

Free Radical Scavenging Potency of Dihydroxybenzoic Acids

In order to evaluate the free radical scavenging potency of dihydroxybenzoic acids (DHBAs) the Density Functional Theory (DFT) was used. The M05-2X/6-311++G(d,p) and B3LYP-D2/6-311++G(d,p) theoretical models were applied. Three possible antioxidant mechanisms were examined: hydrogen atom transfer (HAT), single-electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) mechanisms. All of these mechanisms have been studied in nonpolar (benzene and pentylethanoate) and polar solvents (water) using an implicit solvation model (SMD). The following thermodynamic quantities related to these mechanisms were calculated: bond dissociation enthalpy (BDE), ionization potential (IP), and proton affinity (PA). The obtained results indicated the HAT mechanism as the most favourable reaction pathway for antioxidative action of DHBAs in benzene. On the other hand, SPLET is indicated as predominant reaction mechanism in polar solvent. The SET-PT mechanism was not favourable reaction path for antioxidative action in any of the solvents under investigation

Mechanism of Antiradical Activity of Coumarin-Trihydroxybenzohydrazide Derivatives: A Comprehensive Kinetic DFT Study

As part of this study, the mechanisms of the antioxidant activity of previously synthesized coumarin–trihydrobenzohydrazine derivatives were investigated: (E)-2,4-dioxo-3-(1-(2-(2″,3″,4″-trihydroxybenzoyl)hydrazineyl)ethylidene)chroman-7-yl acetate (1) and (E)-2,4-dioxo-3-(1-(2-(3″,4″,5″-trihydroxybenzoyl)hydrazineyl)ethylidene)chroman-7-yl acetate (2). The capacity of the compounds to neutralize HO• was assessed by EPR spectroscopy. The standard mechanisms of antioxidant action, Hydrogen Atom Transfer (HAT), Sequential Proton Loss followed by Electron Transfer (SPLET), Single-Electron Transfer followed by Proton Transfer (SET-PT), and Radical Adduct/Coupling Formation (RAF/RCF) were examined using the QM-ORSA methodology. It was estimated that the newly synthesized compounds, under physiological conditions, exhibited antiradical activity via SPLET and RCF mechanisms. Based on the estimated overall rate constants (koverall), it can be concluded that 2 exhibited a greater antiradical capacity. The obtained values indicated a good correlation with the EPR spectroscopy results. Both compounds exhibit approximately 1.5 times more activity in comparison to the precursor compound used in the synthesis (gallic acid)

Optimisation of the microdilution method for detection of minimum inhibitory concentration values in selected bacteria

In this study we investigated the influence of preparation of the bacterial inoculum for a microdilution susceptibility test, e.g., the effect of its optical density, on assessment of the minimum inhibitory concentrations (MIC). The approach employed in the majority of microdilution susceptibility studies is use of the same optical density for preparation of inoculums for different bacterial strains. In the present work, this approach was questioned by determining the ratio between the optical density and the number of bacteria in cultures. We also investigated whether the number of bacteria in inoculums can affect assessment of the MIC value for two antibiotics of broad spectra, rifampicin and streptomycin. The study was performed on four Gram-positive and four Gram-negative bacteria (ATCC collection) commonly used to investigate antimicrobial potential. The ratio between the optical density and number of bacteria in cultures was determined for each strain, and a strong linear correlation was detected. However, it was evident that different bacteria have different cell numbers at the same OD600 value. Based on the obtained results, inoculums for selected strains were prepared to obtain final cell numbers of 103, 104, 105 and 106 /well in the microdilution assay. Two different approaches were used in determining the MIC for rifampicin and streptomycin: approximation of MIC with IC90 and the resazurin reduction assay. Our results indicated that the ratio between optical density and cell numbers is not constant and use of the same OD for inoculums for all strains can therefore lead to misinterpretation of the MIC values. We also observed influence of cell numbers in inoculums in determination of MIC values. For both approaches used (approximation of MIC with IC90 and the resazurin reduction assay), the same trend was detected: antibiotics had the highest potency in experiments with the lowest bacteria cell number (103/well). The lowest cell number (103/well) is not recommended, as it can lead to false susceptibility results and to partial reduction of resazurin, which further complicates MIC determination. A final cell number of 104/well can therefore be recommended as optimal

Synthesis and Characterization of 3-(1-((3,4-Dihydroxyphenethyl)amino)ethylidene)-chroman-2,4-dione as a Potential Antitumor Agent

The newly synthesized coumarin derivative with dopamine, 3-(1-((3,4-dihydroxyphenethyl)amino)ethylidene)-chroman-2,4-dione, was completely structurally characterized by X-ray crystallography. It was shown that several types of hydrogen bonds are present, which additionally stabilize the structure. The compound was tested in vitro against different cell lines, healthy human keratinocyte HaCaT, cervical squamous cell carcinoma SiHa, breast carcinoma MCF7, and hepatocellular carcinoma HepG2. Compared to control, the new derivate showed a stronger effect on both healthy and carcinoma cell lines, with the most prominent effect on the breast carcinoma MCF7 cell line. The molecular docking study, obtained for ten different conformations of the new compound, showed its inhibitory nature against CDKS protein. Lower inhibition constant, relative to one of 4-OH-coumarine, proved stronger and more numerous interactions with CDKS protein. These interactions were carefully examined for both parent molecule and derivative and explained from a structural point of view