scholarly journals Investigation into the potential chemical mechanism of the pro-oxidant activity of carotenoids with liposomes under UV-irradiation

2017 ◽  
Vol 82 (9) ◽  
pp. 1009-1023 ◽  
Author(s):  
Dragan Cvetkovic ◽  
Jelena Stanojevic ◽  
Milorad Cakic ◽  
Dejan Markovic
Keyword(s):  
Lipid Bilayers ◽  
Uv Irradiation ◽  
Thiobarbituric Acid ◽  
Peroxyl Radicals ◽  
Chemical Mechanism ◽  
Electron Transfer Mechanism ◽  
Cation Radicals ◽  
Multilamellar Liposomes ◽  
Ft Ir ◽  
Lipid Radicals

This study focuses on the behavior of ?-carotene and lutein inside multilamellar liposomes under continuous UV-irradiation. The liposomes were obtained by the thin film method and carotenoids (Crts) were incorporated by mixing at various concentrations (0.005, 0.0075, 0.02, 0.07 and 0.5 mol %). Liposomes formation and the presence of Crts inside them were confirmed by SEM microscopy and FT-IR spectroscopy, respectively. The antioxidant/pro- -oxidant activity of Crts inside liposomes was determined by the thiobarbituric acid?malondialdehyde (TBA?MDA) test. The investigated Crts acted more or less unexpected (as pro-oxidants) inside the lipid bilayers, interacting with the UV-produced lipid radicals and simultaneously suffering under the UV-irradiation. Their pro-oxidant activity with liposomes and under UV-irradiation could be explained by the formation of unstable adducts in the reaction with peroxyl radicals, or by Crts-cation radicals formation via the electron transfer mechanism. Such tentatively unexpected behavior of carotenoids should be taken into consideration in further carotenoids-based UV-filters projections in cosmetic formulations for skin protection.

scholarly journals UV Irradiation and Ozone Treatment of κ-Carrageenan: Kinetics and Products Characteristics

2020 ◽  
Vol 15 (2) ◽  
pp. 319-330 ◽  
Author(s):  
Aji Prasetyaningrum ◽  
Widayat Widayat ◽  
Bakti Jos ◽  
Yudhy Dharmawan ◽  
Ratnawati Ratnawati
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Uv Irradiation ◽  
Ozone Concentration ◽  
Morphological Properties ◽  
Kinetic Rate Constant ◽  
Kinetic Rate ◽  
Irradiation Intensity ◽  
Ft Ir ◽  
Uv Lamp

The low molecular weight (LMW) of sulfated polysaccharides including k-carrageenan, is shows a wide spectrum of biological activities. This research investigates the influence of UV irradiation, ozone (O3), and the combination of O3/UV methods on the depolymerization of k-carrageenan. The depolymerization kinetics of k-carrageenan using the Advanced Oxidation Process (UV/O3) was also studied. Furthermore, the intrinsic viscosity method was used to determine the average molecular weight of the research sample, and a mathematical model was developed to predict the kinetic rate constant, as a function of ozone dosage and UV irradiation intensity. Therefore, the physicochemical and morphological properties of the degraded k-carrageenan were analyzed by FT-IR, SEM, and XRD. The intrinsic viscosity k-carrageenan decreases with increasing UV light intensity and ozone concentration. The combination of UV/O3 treatment appeared to be more effective than the individual approaches, as the highest kinetic rate constant for depolymerization was 1.924×10-4 min-1, using 125 mg/L ozone concentration and 40 mW/cm2 of UV lamp intensity. This research also evaluated the relationship between various experimental conditions, including UV lamp power dissipation and ozone concentration on the reaction kinetics model, and the results suggest that lower effect is contributed by UV irradiation intensity. In addition, FT-IR spectra showed the absence of any significant change in the functional properties of k-carrageenan treated with UV and O3 processes, although the morphological properties of the LMW k-carrageenan were rougher and more porous than the native k-carrageenan. Copyright © 2020 BCREC Group. All rights reserved 

scholarly journals Synthesis of Certain Poly[bis(benzylidene)] Esters and Investigation on their Photocrosslinkability

2012 ◽  
Vol 9 (1) ◽  
pp. 145-148 ◽  
Author(s):  
D. Roop Singh ◽  
S. Vasanthi ◽  
J. Arul Moli
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Uv Irradiation ◽  
Linear Optics ◽  
Non Linear Optics ◽  
Nmr Spectrometry ◽  
Non Linear ◽  
Photorefractive Materials ◽  
Ft Ir ◽  
Scanning Electron

Random copolyesters were synthesized directly from respective diacids and diols with diphenylchlorophosphate (DPCP) as a polycondensation agent. These polymers were characterized by FT-IR and NMR spectrometry. Interestingly, they were observed to possess photocrosslinkability which was established using scanning electron microscopy by UV irradiation experiments. Photocrosslinkable polymers have significant applications in the field of non-linear optics, in the generation of photoresists and photorefractive materials.

scholarly journals l-carnosine (β-alanyl-l-histidine) and carcinine (β-alanylhistamine) act as natural antioxidants with hydroxyl-radical-scavenging and lipid-peroxidase activities

1994 ◽  
Vol 304 (2) ◽  
pp. 509-516 ◽  
Author(s):  
M A Babizhayev ◽  
M C Seguin ◽  
J Gueyne ◽  
R P Evstigneeva ◽  
E A Ageyeva ◽  
...  
Keyword(s):  
Linoleic Acid ◽  
Direct Reduction ◽  
Radical Scavenging ◽  
Thiobarbituric Acid ◽  
Natural Antioxidants ◽  
Peroxyl Radicals ◽  
Lipid Phase ◽  
Oh Radicals ◽  
Thiobarbituric Acid Reactive Substance ◽  
Lipid Hydroperoxides

Carnosine (beta-alanyl-L-histidine) and carcinine (beta-alanylhistamine) are natural imidazole-containing compounds found in the non-protein fraction of mammalian tissues. Carcinine was synthesized by an original procedure and characterized. Both carnosine and carcinine (10-25 mM) are capable of inhibiting the catalysis of linoleic acid and phosphatidylcholine liposomal peroxidation (LPO) by the O2(-.)-dependent iron-ascorbate and lipid-peroxyl-radical-generating linoleic acid 13-monohydroperoxide (LOOH)-activated haemoglobin systems, as measured by thiobarbituric-acid-reactive substance. Carcinine and carnosine are good scavengers of OH. radicals, as detected by iron-dependent radical damage to the sugar deoxyribose. This suggests that carnosine and carcinine are able to scavenge free radicals or donate hydrogen ions. The iodometric, conjugated diene and t.l.c. assessments of lipid hydroperoxides (13-monohydroperoxide linoleic acid and phosphatidylcholine hydroperoxide) showed their efficient reduction and deactivation by carnosine and carcinine (10-25 mM) in the liberated and bound-to-artificial-bilayer states. This suggests that the peroxidase activity exceeded that susceptible to direct reduction with glutathione peroxidase. Imidazole, solutions of beta-alanine, or their mixtures with peptide moieties did not show antioxidant potential. Free L-histidine and especially histamine stimulated iron (II) salt-dependent LPO. Due to the combination of weak metal chelating (abolished by EDTA), OH. and lipid peroxyl radicals scavenging, reducing activities to liberated fatty acid and phospholipid hydroperoxides, carnosine and carcinine appear to be physiological antioxidants able to efficiently protect the lipid phase of biological membranes and aqueous environments.

PREPARATION OF POLYMER BRUSHES FROM POLY(VINYLIDENE FLUORIDE) SURFACES BY UV IRRADIATION PRETREATMENT

2007 ◽  
Vol 14 (01) ◽  
pp. 23-30 ◽  
Author(s):  
QILAN DENG ◽  
YIWANG CHEN ◽  
WEI SUN
Keyword(s):  
Methyl Methacrylate ◽  
Uv Irradiation ◽  
Photoelectron Spectroscopy ◽  
Polymer Brushes ◽  
Vinylidene Fluoride ◽  
Contact Angles ◽  
Water Contact ◽  
Air Exposure ◽  
Poly Vinylidene Fluoride ◽  
Ft Ir

Grafting of polymer brushes from the poly(vinylidene fluoride) (PVDF) surfaces was carried out. The active species, such as peroxide and hydroperoxide, on the surface were generated via ultraviolet (UV) irradiation pretreatment in nitrogen, followed by air exposure. Homopolymer brushes of methyl methacrylate (MMA) were prepared by the surface-initiated free radical polymerization from the peroxide initiators on the PVDF surface. The peroxides formed on UV-treated and air-exposed PVDF surfaces were determined quantitatively by the reaction with 2,2-diphenyl-1-picrylhydrazyl (DPPH) in toluene. The chemical composition and topography of the graft-functionalized PVDF surfaces were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance (ATR) FT-IR spectroscopy, and atomic force microscopy (AFM). ATR FT-IR revealed an increase in the graft concentration of poly(methyl methacrylate) (PMMA) on PVDF surfaces with an increase of the UV irradiation pretreatment time. Water contact angles on PVDF surfaces were reduced by surface grafting of PMMA.

Ferutinin as a Ca2+complexone: lipid bilayers, conductometry, FT-IR, NMR studies and DFT-B3LYP calculations

2015 ◽  
Vol 44 (37) ◽  
pp. 16506-16515 ◽  
Author(s):  
A. Dubis ◽  
M. V. Zamaraeva ◽  
L. Siergiejczyk ◽  
O. Charishnikova ◽  
V. Shlyonsky
Keyword(s):  
Lipid Bilayers ◽  
Nmr Studies ◽  
B3lyp Calculations ◽  
Ft Ir

Spatial re-orientation of two initially H-bonded ferutinin molecules upon Ca2+complexation.

Surface Modification of Alumina Nano-Particles by UV-Induced Grafting Polymerization of 2-Hydroxyethyl Methacrylate

2010 ◽  
Vol 93-94 ◽  
pp. 95-98 ◽  
Author(s):  
K. Yantaboot ◽  
S. Maensiri ◽  
Paveena Khansawai ◽  
Sittipong Amnuaypanich
Keyword(s):  
Uv Irradiation ◽  
Irradiation Time ◽  
Nano Particles ◽  
Hydroxyethyl Methacrylate ◽  
Alumina Surface ◽  
Sequential Method ◽  
Grafting Polymerization ◽  
Alumina Particles ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Alumina nano-particles was grafted with poly(2-hydroxyethyl methacrylate) (PHEMA) utilizing the sequential method; that is, the alumina surface was first rendered with initiator, benzophenone, by UV-irradiation followed by the grafting polymerization of HEMA on the surface which was initiated thermally and propagated via the free-radical polymerization. FT-IR spectroscopy confirmed the successful grafting of PHEMA onto the alumina surface. Determined by thermalgravimetry (TG), the amount of benzophenone on the alumina surface was found to increase with the UV-irradiation time; however upon grafting of PHEMA, the amount of grafted-PHEMA was the same irrespective of the reaction time. The glass transition temperature (Tg) of grafted-PHEMA on alumina particles was approximately 93 °C that is higher than that of PHEMA which has Tg around 85 °C. This indicates the more restricted movement of grafted-PHEMA compared with the ungrafted-PHEMA.

scholarly journals Antioxidant and Antiradical Properties of Some Examples of Flavonoids and Coumarins—Potentiometric Studies

Chemosensors ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 112
Author(s):  
Elena Gerasimova ◽  
Elena Gazizullina ◽  
Ekaterina Radosteva ◽  
Alla Ivanova
Keyword(s):  
Electron Transfer ◽  
Cyclic Voltammetry ◽  
Antioxidant Properties ◽  
Hydrogen Atom Transfer ◽  
Peroxyl Radicals ◽  
Mutual Arrangement ◽  
Hydroxyl Groups ◽  
Metal Chelation ◽  
Electron Transfer Mechanism ◽  
Antiradical Properties

A comprehensive study of a range of flavonoids and coumarins is presented in this article. The work uses an approach that evaluates the activity of these compounds by various mechanisms: the electron transfer (ET), the hydrogen atom transfer (HAT), and the mechanism of metal chelation. The studies were carried out using the methods of the cyclic voltammetry and the potentiometry. The electrochemical behavior of these compounds was studied by the method of cyclic voltammetry; the main types of voltammograms, depending on the oxidation mechanisms, were identified. Various versions of potentiometric sensor systems have been used to detect analytical signal in approaches implemented in ET, HAT and metal chelation mechanisms. The antioxidant capacity was studied by the electron-transfer mechanism. Compounds with antioxidant properties were selected; half-reaction periods for these compounds have been determined. It has been shown that electron-donating and complexing properties directly depend on the mutual arrangement of hydroxyl groups in the molecule. The antiradical ability of the compounds has been studied. It was shown that all studied compounds inhibit peroxyl radicals. Series on the change in antioxidant and antiradical properties of compounds have been compiled. There is no correlation between the results of the study of antioxidant properties obtained using sensory systems that reveal various antioxidant mechanisms. The need to use an integrated approach in the study of antioxidant properties is shown.

Excited State Charge Transfer in Dyads of ZnO Nanocrystals and Organic or Transition Metal Dyes

2010 ◽  
Vol 1260 ◽  
Author(s):  
Julia E. Saunders ◽  
Adam S. Huss ◽  
Jon Bohnsack ◽  
Kent R. Mann ◽  
David A. Blank ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Room Temperature ◽  
Surface Coverage ◽  
Dye Molecules ◽  
Electron Transfer Mechanism ◽  
Dye Sensitized ◽  
Zno Nanocrystals ◽  
Carboxylate Groups ◽  
Ft Ir ◽  
State Charge

AbstractTo better understand the specific charge transfer events that occur within a dye-sensitized solar cell (DSSC), we synthesized well-defined ZnO:dye dyads. The ZnO nanocrystals were synthesized following literature procedures from zinc acetate and a hydroxide source in ethanol. The absorption onset of the ZnO nanocrystals was observed using UV-vis measurements, from which estimated nanocrystal diameters were determined. At room temperature, the synthesis yielded nanocrystals ranging in diameter from 2-4 nm. Dispersions of ZnO nanocrystals in ethanol were mixed with solutions containing 5΄΄-phenyl-3΄,4΄-di(nbutyl)-[2,2΄:5΄,2΄΄] terthiophene-5-carboxylic acid. Using FT-IR and fluorescence spectroscopy, it was verified that the dye molecules were adsorbed to the ZnO surface via their carboxylate groups while the number of dye molecules adsorbed to the surface was quantified using a combination of techniques. Adsorption isotherms were employed to probe surface coverage of the dye onto the nanocrystals to yield an adsorption equilibrium constant of 1.5 ± 0.2 x 105 M-1. The ability of ZnO nanocrystals to quench the emission of the dye by an electron transfer mechanism was observed and elucidated using ultra-fast laser spectroscopy where the time-scale for electron injection from the dye to the ZnO was determined to be 5.5 ps.

scholarly journals Erythrocyte osmotic fragility test as the measure of defence against free radicals in rabbits of different age

2001 ◽  
Vol 49 (4) ◽  
pp. 413-419 ◽  
Author(s):  
Ewa Brzezińska-Ślebodzińska
Keyword(s):  
Free Radicals ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Membrane Lipids ◽  
Antioxidant Properties ◽  
Osmotic Fragility ◽  
Thiobarbituric Acid ◽  
Peroxyl Radicals ◽  
Antioxidant Defence System

Peroxidation of the unsaturated bonds of membrane lipids increases fragility and cellular lysis of red blood cells. Erythrocyte susceptibility to the free radicals (peroxyl radicals) generated in vitro by 2,2′-azo-bis(2-amidinopropane) hydrochloride (AAPH) was evaluated and expressed as 50% maximal haemolysis time (HT50) in 3 groups of rabbits of different age. Erythrocytes of 1.5-month-old rabbits were more sensitive to free radicals than those of 3.5- and 6-month-old ones. In the three groups, significant negative correlation (r = −0.8 to −0.98) between the lipid peroxidation rate (thiobarbituric acid reactive substances; TBARS concentration) in blood plasma and the erythrocyte resistance to free radicals was found. This result suggests that the plasma antioxidant defence system is interrelated with that of the red blood cells and that the erythrocytes can be a good model for studies of oxidative stress. The simple haemolysis test reflecting the free radical defence can be useful for evaluating the antioxidant properties of various compounds.

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