No abstract

No abstract

No abstract

The purpose of the present study was to evaluate the antioxidant and antimicrobial potential of Filipendula ulmaria (L.) Maxim. methanolic extracts, their stabilities under different pH and thermal conditions and in vitro digestibility. The results showed a considerable content of phenolic compounds in the extracts, especially total phenolic acids (47.47 mg CAE g(-1)) and flavonoids (45.47 mg RUE g(-1)) in aerial parts. HPLC analysis indicated the presence of spiraeoside in the aerial part extract. The extracts revealed an interesting antimicrobial effect against the tested microorganisms, especially bacteria E. coli and E. faecalis (MIC 0.156-0.625 mg mL(-1)), and fungi P. cyclopium and F. oxysporum (MIC 2.5-5 mg mL(-1)). The extracts exerted high antioxidant activities, particularly the root extract, paralleled by their considerable activities against the lipid oxidation process. The results of this study suggest that both extracts potentially could be functional food ingredients considering their good antioxidant and antimicrobial activities, and stability under different conditions.

Several novel 4-hydroxy-chromene-2-one derivatives 2b-16b were easily prepared through condensation reactions with microwave heating and characterized by elemental analysis, IR, 1H-NMR and mass spectrometry. Geometry optimization of these compounds was executed by PM3, PM5 and Minimize Energy methods to describe them via molecular descriptors. The antimicrobial activity of the synthesized compounds was evaluated against different microbial strains using two different methods: the diffusion method and the micro-dilution method. All data indicated that the products possess antimicrobial activity which depends on the nature of substituent attached to the benzopyran moiety. In general, after 24 h the MIC values of most tested coumarins was 0.13 mg/mL, but compounds 1 and 6b displayed the strongest antimicrobial activity on the tested cultures of bacteria after 48 h. Compound 13b has the strongest growth inhibitory potential on fungus C. albicans, tested by diffusion method, with an inhibition zone of 30-37 mm at a concentration of 150 µg/mL. The conclusion of this experiment is that the synthesized compounds have varied and different influence on different classes of bacteria and the fungus C. albicans.

Monoamine oxidase B (MAO B) catalyzes the oxidative deamination of aryalkylamines neurotransmitters with concomitant reduction of oxygen to hydrogen peroxide. Consequently, the enzyme's malfunction can induce oxidative damage to mitochondrial DNA and mediates development of Parkinson's disease. Thus, MAO B emerges as a promising target for developing pharmaceuticals potentially useful to treat this vicious neurodegenerative condition. Aiming to contribute to the development of drugs with the reversible mechanism of MAO B inhibition only, herein, an extended in silico-in vitro procedure for the selection of novel MAO B inhibitors is demonstrated, including the following: (1) definition of optimized and validated structure-based three-dimensional (3-D) quantitative structure-activity relationships (QSAR) models derived from available cocrystallized inhibitor-MAO B complexes; (2) elaboration of SAR features for either irreversible or reversible MAO B inhibitors to characterize and improve coumarin-based inhibitor activity (Protein Data Bank ID: 2V61 ) as the most potent reversible lead compound; (3) definition of structure-based (SB) and ligand-based (LB) alignment rule assessments by which virtually any untested potential MAO B inhibitor might be evaluated; (4) predictive ability validation of the best 3-D QSAR model through SB/LB modeling of four coumarin-based external test sets (267 compounds); (5) design and SB/LB alignment of novel coumarin-based scaffolds experimentally validated through synthesis and biological evaluation in vitro. Due to the wide range of molecular diversity within the 3-D QSAR training set and derived features, the selected N probe-derived 3-D QSAR model proves to be a valuable tool for virtual screening (VS) of novel MAO B inhibitors and a platform for design, synthesis and evaluation of novel active structures. Accordingly, six highly active and selective MAO B inhibitors (picomolar to low nanomolar range of activity) were disclosed as a result of rational SB/LB 3D QSAR design; therefore, D123 (IC = 0.83 nM, K = 0.25 nM) and D124 (IC = 0.97 nM, K = 0.29 nM) are potential lead candidates as anti-Parkinson's drugs.

The series of fifteen synthesized 4-hydroxycoumarin derivatives was subjected to antioxidant activity evaluation in vitro, through total antioxidant capacity, 1,1-diphenyl-2-picryl-hydrazyl (DPPH), hydroxyl radical, lipid peroxide scavenging and chelating activity. The highest activity was detected during the radicals scavenging, with 2b, 6b, 2c, and 4c noticed as the most active. The antioxidant activity was further quantified by the quantitative structure-activity relationships (QSAR) studies. For this purpose, the structures were optimized using Paramethric Method 6 (PM6) semi-empirical and Density Functional Theory (DFT) B3LYP methods. Bond dissociation enthalpies of coumarin 4-OH, Natural Bond Orbital (NBO) gained hybridization of the oxygen, acidity of the hydrogen atom and various molecular descriptors obtained, were correlated with biological activity, after which we designed 20 new antioxidant structures, using the most favorable structural motifs, with much improved predicted activity in vitro.

The effects of subchronic exposure to copper (Cu) on lipid peroxidation, hemato-biochemical parameters, and the possible protective role of flavonoids Quercetin and (-)-Epicatechin were studied. Male Wistar albino rats were treated with Cu (560 mg/L, p.o. as CuCl2?2H2O for 5 weeks) and Quercetin and (-)-Epicatechin (40 mg/kg BW each, i.p., every third day during the last 3 weeks) alone or in combination. Cu increased the concentration of lipid peroxides, decreased the number of erythrocytes, hemoglobin and hematocrit values and increased the activities of aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase. Coadministration of Quercetin and (-)-Epicatechin with Cu lowered the process of lipid peroxidation and restored examined hemato-biochemical parameters to control values. Our results indicate that Cu induced oxidative damage in erythrocytes, which led to anemia, while Quercetin and (-)-Epicatechin showed a protective effect on the hemato-biochemical processes in the blood of rats. [Projekat Ministarstva nauke Republike Srbije, br. 173041]