Search results for "SUBSTANCES"
showing 10 items of 1122 documents
Role of paramagnetic polyconjugated clusters in lignin antioxidant activity(in vitro)
2012
Using physico-chemical methods (EPR, SEC, Py-GC/MS and UV/VIS spectroscopy) and wet chemical analysis, the characteristics of 6 hardwood lignins in terms of functionality, molecular weight and composition of lignin substructures were determined and considered together with the results of DPPH•, ABTS•+ and O2•− antioxidant assays with the aim to understand the relationships governing antioxidant properties of lignin. The strong positive linear correlation between lignin antioxidant capacity in the three assays used and the extent of conjugation of paramagnetic polyconjugated clusters in lignin macromolecules was found. The biological activity of the most active alkaline lignins was assessed …
Bioactive components of caper (Capperis spinosa L.) from Sicily and antioxidant effects in a red meat simulated gastric digestion
2007
An increasing body of evidence on the association between adherence to the Mediterranean diet and healthy status is being accumulated. Floral buds of Capparis spinosa L. are commonly used in the Mediterranean cuisine as flavoring for meat and other foods. The present study evaluated bioactive components and antioxidant activity of Sicilian capers stabilized in salt. Whereas alpha-tocopherol was absent, low levels of gamma-tocopherol and vitamin C were measured. With reference to one serving size (8.6 g of capers), rutin was 13.76 mg, isothiocyanates, recently acknowledged as anticarcinogen phytochemicals, were 42.14 micromol, total phenols were 4.19 mg of gallic acid equivalents (GAE), and …
The role of glutathione in protection against DNA damage induced by rifamycin SV and copper(II) ions.
1993
Incubation of calf thymus DNA in the presence of rifamycin SV induces a decrease in the absorbance of DNA at 260 nm. The effect, was found to be proportional to the antibiotic concentration and enhanced by copper(II) ions. In the presence of rifamycin SV and copper(II), a significant increase in thiobarbituric acid-reactive (TBA-reactive) material is also observed. This effect is inhibited to different degrees by the following antioxidants: catalase 77%; thiourea 72%; glutathione (GSH) 62%; ethanol 52%; and DMSO 34%, suggesting that both hydrogen peroxide (H2O2) and hydroxyl radicals (OH.) are involved in DNA damage. Rifamycin SV-copper(II) mixtures were also found to induce the production …
Overview of pesticide use in Moroccan apple orchards and its effects on the environment
2021
International audience; The cultivation of apple trees needs to use phytosanitary products, which are used in an irrational way by certain farmers. The harmful effects of pesticides result mainly from their persistence in the environment. Several studies have been carried out to estimate the pesticide residues and assess their effects on soil microorganisms and aquatic organisms. The results of these studies have revealed a harmful effect on these bioindicators. Therefore, a disruption in their growth and reproduction, an increase in their mortality, and a decrease in their fertility have been proven. In addition, a considerable reduction in the number and diversity of soil microorganisms a…
Special Uses of Viscoelastics
2000
The possibilities of viscoelastic use in phacoemulsification will be outlined in the following figures. Many ophthalmic surgeons apply viscoelastic substances in capsulorhexis to achieve a deep anterior chamber and extend the pupillary space (with a small pupil). Care must be taken during injection so that aqueous is permitted to flow out. When using a paracentesis to inject viscoelastic (Fig. 59), it must be big enough to allow aqueous outflow. For complete aqueous exchange in the anterior chamber, it is advisable to inject the viscoelastic into the opposite chamber angle.
New hydrogel matrices based on chemical crosslinked α,β -polyas parthydrazide: Synthesis, characterization and in vivo biocompatibility studies
1996
New swellable micromatrices of α,β-polyasparthydrazide (PAHy) crosslinked with glutaraldehyde were prepared. The effect of crosslinking agent concentration was evaluated. In particular, crosslinking density affected aqueous dynamic swelling and glass-transition temperature of the material. The structure of prepared networks was also studied by scanning electron microscopy and X-ray analysis. Finally, biocompatibility of PAHy derivatives was investigated in vivo by subcutaneous implantation and in oral administration to laboratory animals.
Micellar Liquid Chromatography: Fundamentals
2015
The reversed phase liquid chromatography (RPLC) mode with surfactant above the critical micellar concentration (CMC) has been called micellar liquid chromatography (MLC). In pure micellar systems, the retention behavior is explained by considering three phases or environments: surfactant-modified stationary phase, bulk aqueous solvent, and micellar pseudo-phase. Surfactant adsorption on the porous RPLC packing affects chromatographic retention, owing to the change of diverse surface properties of the stationary phase. In pure micellar systems, the retention behavior is explained by considering three phases or environments: surfactant-modified stationary phase, bulk aqueous solvent, and mice…
Excess enthalpies of solution of primary and secondary alcohols in dodecyldimethylamine oxide micellar solutions
1987
The excess enthalpies of solution with respect to water of some primary and secondary alcohols in dodecyldimethylamine oxide (DDAO) micellar solutions were measured by mixing aqueous solutions of alcohols with surfactant solutions. Standard free energies, enthalpies and entropies were obtained from the distribution of alcohols between aqueous and micellar phases. It is shown that thermodynamics of transfer of secondary alcohols from aqueous to the DDAO micellar phase differ slightly from those of their corresponding primary alcohols, that the additivity rule holds for free energies of transfer and that enthalpy and entropy display convex curves. The present data are compared with those from…
N-Alkyl Ammonium Resorcinarene Chloride Receptors for Guest Binding in Aqueous Environment
2016
Host systems with guest binding ability in water and/or biological fluids are a current challenge in supramolecular host–guest chemistry. Here we present the first syntheses of water-soluble N-ethanol ammonium resorcinarene chlorides (NARCls) with terminal hydroxyl groups at the upper rim. The NARCls possess deep cavities and are shown to bind a variety of guest molecules such as linear and cyclic alkanes, linear halogenated alkanes, and aromatic fluorophores (naphthalene, p-(phenylazo)phenol) in water through hydrophobic interactions, as well as 1,4-dioxane (a water soluble guest) via hydrogen bonds. The receptors are monomeric in aqueous media and form 1:1 host–guest complexes with bindin…
The role of Aurora-A inhibitors in cancer therapy
2007
Recently, new chemotherapy agents which target the non-structural components of mitosis have been developed. An important protein involved in several mitotic phases is the Aurora-A protein. By means of the phosphorylation of different substrates, Aurora-A regulates the correct development of the various phases of mitosis. The kinase activity of this protein makes Aurora-A an excellent candidate as an oncogene. The first data of Aurora-A involvement in cancer regarded the identification of Aurora-A overexpression in primary breast and colon tumour samples. With regard to the predictive role of Aurora-A, it has been shown that its overexpression disrupts the spindle checkpoint activated by pa…