ABSTRACT
Derivatization of the natural flavonoid dihydroquercetin with p-aminobenzoic acid was carried out in an ethyl acetate/citric buffer biphasic system using laccase from the fungus Trametes hirsuta. The main reaction product yield was ~68 mol %. The product was characterized by 1H NMR, 13C NMR, and liquid chromatography-mass spectroscopy, and its structure was elucidated. The reaction product affected viability of cultured human rhabdomyosarcoma cells (RD cell line) in a dose-dependent manner and, therefore, can be of interest to pharmaceutical industry.
Subject(s)
4-Aminobenzoic Acid/chemistry , Biocatalysis , Laccase/metabolism , Quercetin/analogs & derivatives , Acetates/chemistry , Cell Line, Tumor , Citric Acid/chemistry , Humans , Quercetin/chemistry , Trametes/enzymologyABSTRACT
Evolution of the theoretical spectrum during the course of spectrum analysis and comparison of the result with the experimental spectrum.
ABSTRACT
Novel fluorescent derivatives of macrolide antibiotics related to tylosin bearing rhodamine, fluorescein, Alexa Fluor 488, BODIPY FL, and nitrobenzoxadiazole (NBD) residues were synthesized. The formation of complexes of these compounds with 70S E. coli ribosomes was studied by measuring the fluorescence polarization depending on the ribosome amount at constant concentration of the fluorescent substance. With the synthesized fluorescent tylosin derivatives, the dissociation constants for ribosome complexes with several known antibiotics and macrolide analogs previously obtained were determined. It was found that the fluorescent tylosin derivatives containing BODIPY FL and NBD groups could be used to screen the binding of novel antibiotics to bacterial ribosomes in the macrolide-binding site.
Subject(s)
Escherichia coli/chemistry , Fluorescent Dyes/chemistry , Ribosomes/chemistry , Tylosin/analogs & derivatives , Tylosin/chemistryABSTRACT
The novel algorithm for a total lineshape analysis of high-resolution NMR spectra has been developed. A global optimization by simulated annealing has been applied that has allowed to overcome the main trouble of common approaches which had frequently returned solutions for local minima rather than for global ones. The algorithm has been verified for the four-spin test systems ABCD, and has been successfully used for analysis of experimental NMR spectra of proline. The approach has allowed to avoid a sophisticated manual setup of initial parameters and to conduct the analysis of complicated high-resolution NMR spectra nearly automatically.
ABSTRACT
Dihydroquercetin (or taxifolin) is one of the most famous flavonoids and is abundant in Siberian larch (Larix sibirica). The oxidative polymerization of dihydroquercetin (DHQ) using bilirubin oxidase as a biocatalyst was investigated and some physicochemical properties of the products were studied. DHQ oligomers (oligoDHQ) with molecular mass of 2800 and polydispersity of 8.6 were obtained by enzymatic reaction under optimal conditions. The oligomers appeared to be soluble in dimethylsulfoxide, dimethylformamide, and methanol. UV-visible spectra of oligoDHQ in dimethylsulfoxide indicated the presence of highly conjugated bonds. The synthesized oligoDHQ was also characterized by FTIR and (1)H and (13)C NMR spectroscopy. Comparison of NMR spectra of oligoDHQ with DHQ monomer and the parent flavonoids revealed irregular structure of a polymer formed via the enzymatic oxidation of DHQ followed by nonselective radical polymerization. As compared with the monomer, oligoDHQ demonstrated higher thermal stability and high antioxidant activity.
Subject(s)
Antioxidants/metabolism , Oxidoreductases Acting on CH-CH Group Donors/metabolism , Quercetin/analogs & derivatives , Antioxidants/chemistry , Oxidation-Reduction , Polymerization , Polymers/chemistry , Quercetin/chemistry , Quercetin/metabolismABSTRACT
Fourteen new functionally active amino acid and peptide derivatives of the antibiotics tylosin, desmycosin, and 5-O-mycaminosyltylonolide were synthesized in order to study the interaction of the growing polypeptide chain with the ribosomal tunnel. The conjugation of various amino acids and peptides with a macrolide aldehyde group was carried out by two methods: direct reductive amination with the isolation of the intermediate Schiff bases or through binding via oxime using the preliminarily obtained derivatives of 2-aminooxyacetic acid.
Subject(s)
Amino Acids/chemical synthesis , Anti-Bacterial Agents/chemical synthesis , Oligopeptides/chemical synthesis , Tylosin/analogs & derivatives , Tylosin/chemical synthesis , Amino Acids/chemistry , Anti-Bacterial Agents/chemistry , Oligopeptides/chemistry , Tylosin/chemistryABSTRACT
Synthesis of cationic plastoquinone derivatives (SkQs) containing positively charged phosphonium or rhodamine moieties connected to plastoquinone by decane or pentane linkers is described. It is shown that SkQs (i) easily penetrate through planar, mitochondrial, and outer cell membranes, (ii) at low (nanomolar) concentrations, posses strong antioxidant activity in aqueous solution, BLM, lipid micelles, liposomes, isolated mitochondria, and cells, (iii) at higher (micromolar) concentrations, show pronounced prooxidant activity, the "window" between anti- and prooxidant concentrations being very much larger than for MitoQ, a cationic ubiquinone derivative showing very much lower antioxidant activity and higher prooxidant activity, (iv) are reduced by the respiratory chain to SkQH2, the rate of oxidation of SkQH2 being lower than the rate of SkQ reduction, and (v) prevent oxidation of mitochondrial cardiolipin by OH*. In HeLa cells and human fibroblasts, SkQs operate as powerful inhibitors of the ROS-induced apoptosis and necrosis. For the two most active SkQs, namely SkQ1 and SkQR1, C(1/2) values for inhibition of the H2O2-induced apoptosis in fibroblasts appear to be as low as 1x10(-11) and 8x10(-13) M, respectively. SkQR1, a fluorescent representative of the SkQ family, specifically stains a single type of organelles in the living cell, i.e. energized mitochondria. Such specificity is explained by the fact that it is the mitochondrial matrix that is the only negatively-charged compartment inside the cell. Assuming that the Deltapsi values on the outer cell and inner mitochondrial membranes are about 60 and 180 mV, respectively, and taking into account distribution coefficient of SkQ1 between lipid and water (about 13,000 : 1), the SkQ1 concentration in the inner leaflet of the inner mitochondrial membrane should be 1.3x10(8) times higher than in the extracellular space. This explains the very high efficiency of such compounds in experiments on cell cultures. It is concluded that SkQs are rechargeable, mitochondria-targeted antioxidants of very high efficiency and specificity. Therefore, they might be used to effectively prevent ROS-induced oxidation of lipids and proteins in the inner mitochondrial membrane in vivo.
Subject(s)
Aging , Antioxidants/metabolism , Mitochondria/metabolism , Plastoquinone/metabolism , Antioxidants/chemical synthesis , Antioxidants/chemistry , Apoptosis , Biological Transport , Cells, Cultured , Fibroblasts/chemistry , Fibroblasts/cytology , Fibroblasts/metabolism , HeLa Cells , Humans , Mitochondria/chemistry , Mitochondrial Membranes/chemistry , Mitochondrial Membranes/metabolism , Necrosis , Oxidation-Reduction , Plastoquinone/analogs & derivatives , Plastoquinone/chemical synthesisABSTRACT
[figure: see text] The structure of the complex between lanthanum(III)nitrate and 1,9-diaza-18-crown-6 is analyzed with three independent methods. The conformation observed by analysis of vicinal NMR coupling constants in solution agrees with both the one found by a single crystal X-ray study and with simulations by molecular orbital and force field calculations. In the acetonitrile solution, the NMR data show a bent crown conformation with nearly C2v symmetry, which is stable on the NMR time scale.
