Search results

1

Role of antioxidant vitamins administration on the oxidative stress

100%

Tomoeda M., Kubo C., Yoshizawa H., Yuki M., Kitamura M., Nagata S., Murakami M., Nishizawa Y., Tomita Y.

Open Medicine

|

2013

|

vol. 8

|

issue 4

509-516

EN

The health-promoting effects of antioxidant vitamins C and E supplementation are unclear. This study investigated the effects of vitamins C and E on the activities of reactive oxygen species (ROS)-scavenging enzymes and protein and lipid peroxidation statuses under resting and exercise-induced conditions. Thirteen healthy, previously untrained males (age 20–21 years) participated in this study. Seven subjects performed physical exercise using a cycle ergometer, and six performed a 6-min walk test (6MWT) prior to vitamin administration and after 1-week oral administration of vitamin C (1000 mg/day) and vitamin E (300 IU/day). Venous blood samples were collected before and after exercise. Plasma vitamin C concentration, superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, and protein carbonyl and thiobarbituric acid-reactive substance (TBARS) contents were measured. Antioxidant supplementation increased vitamin C concentration by 34% (p<0.05), decreased SOD activity by 17% (p<0.05), increased GPx activity by 13% (p<0.05), and increased the GPx/SOD activity ratio by 37% (p<0.05). Protein carbonyl and TBARS contents were unaffected. Antioxidant vitamins effectively increase the plasma GPx/SOD activity ratio, but fail to reduce protein carbonyl levels induced by exercise.

2

Consequence of hydrogen atom abstraction from 5’-hydroxyl group of 2’-deoxyadenosine. Theoretical quantum mechanics study

88%

Karwowski B.

Open Chemistry

|

2008

|

vol. 6

|

issue 3

450-455

EN

Reactive oxygen species (ROS) may generate different nucleoside/nucleotide radicals in a cell environment. In this study, the possibility of cyclic-2’-deoxyadenosines formation by a rearrangement of their free radicals was investigated. It seems that for cyclic-nucleosides formation, adoption of an O4’-exo conformation by the sugar moiety is necessary. However, this is the energetically unfavoured form of the 2-deoxyribose ring. Moreover, the creation of a O5’, C8 bond in purine deoxy-nucleosides/nucleotides leads to the termination of the DNA elongation process. [...]

3

Antioxidative responses to seasonal changes and chemiluminescence assay of Astragalus onobrychis leaves extract

88%

Miladinović D., Ilić B., Najman S., Cvetković O., Šajnović A., Miladinović M., Nikolić N.

Open Chemistry

|

2013

|

vol. 11

|

issue 2

123-132

EN

The aim of this study was to research the seasonal changes of antioxidant enzyme activity and total antioxidant capacity in leaves of Astragalus onobrychis L. subsp. chlorocarpus (Griseb.) S. Kozuharov et D.K. Pavlova. Leaves of A. onobrychis were collected during the different stages of growth and analyzed for antioxidant enzyme activity: superoxide dismutase, catalase, guaiacol peroxidase, glutathione peroxidase. Quantities of malonyldialdehyde, superoxide radicals, and hydroxyl radicals were measured as well as the content of soluble proteins. Furthermore, total antioxidant capacity was determined by the inhibition of chemiluminescence activity of blood phagocytes by leaf extracts. Stages of vegetation significantly affected the accumulation of superoxide radicals, but there were no significant differences in hydroxyl radical quantity and lipid peroxidation levels during vegetation. Soluble proteins vary greatly between different stages of growth. Seasonal changes were found to have an effect on enzymatic activities. During the spring season, guaiacol peroxidase showed the highest levels. Catalase and glutathione peroxidase increased their activities in summer, while, during the autumn season, superoxide dismutase showed maximum activity. On the basis of chemiluminescence assay, it can be concluded that leaf extract of A. onobrychis possesses a significant antioxidant capacity thus protecting plants during environmental stress. [...]

4

The difference in stability between 5′R and 5′S diastereomers of 5′,8-cyclopurine-2′-deoxynucleosides. DFT study in gaseous and aqueous phase

88%

Karwowski B.

Open Chemistry

|

2010

|

vol. 8

|

issue 1

134-141

EN

Oxidatively generated damage to DNA frequently appears in the human genome as an effect of aerobic metabolism or as the result of exposure to exogenous oxidizing agents. Due to these facts it has been decided to calculate the stability of 5′,8-cyclo-2′-deoxyadenosine/guanosine (cdA, cdG) in their 5′R and 5′S diastereomeric forms. For all points of quantum mechanics studies presented, the density functional theory (DFT) with B3LYP parameters on 6-311++G** basis set level was used. The calculations showed a significant negative enthalpy for glycosidic bond cleavage reaction for cationic forms and slightly negative for neutral ones. The preliminary study of the discussed process has shown the nature of stepwise nucleophilic substitution DN*AD type mechanism. Surprisingly, the different values in free energy, between short-lived oxacarbenium ion intermediates, have been found to lie over a relatively small range, around 1 and 2.8 kcal mol−1. For anions, the decomposition enthalpies were found as positive in aqueous phases. These theoretical results are supported by the formic acid hydrolysis experiments of both diastereomers of cdA, for the first time. (5′S)cdA exhibited higher stability than (5′R)cdA. [...]

5

DNA-based biosensors with external Nafion and chitosan membranes for the evaluation of the antioxidant activity of beer, coffee, and tea

88%

Hlavatá L., Vyskočil V., Beníková K., Borbélyová M., Labuda J.

|

issue 5

604-611

EN

Novel electrochemical DNA-based biosensors with outer-sphere Nafion and chitosan protective membranes were prepared for the evaluation of antioxidant properties of beverages (beer, coffee, and black tea) against prooxidant hydroxyl radicals. A carbon working electrode of a screen-printed three-electrode assembly was modified using a layer-by-layer deposition technique with low molecular weight double-stranded DNA and a Nafion or chitosan film. The membrane-covered DNA biosensors were initially tested with respect to their voltammetric and impedimetric response after the incubation of the beverage and the medium exchange for the solution of the redox indicator [Fe(CN)6]3−/4−. While the Nafion-protected biosensor proved to be suitable for beer and black tea extracts, the chitosan-protected biosensor was successfully used in a coffee extract. Afterwards, the applicability was successfully verified for these biosensors for the detection of a deep degradation of the surface-attached DNA at the incubation in the cleavage agent (hydroxyl radicals generated via Fenton reaction) and for the evaluation of antioxidant properties of coffee and black tea extracts against prooxidant hydroxyl radicals. The investigation of the novel biosensors with a protective membrane represents a significant contribution to the field of electrochemical DNA biosensors utilization.

6

UVB PROTECTIVE, ANTI-AGING, AND ANTI-INFLAMMATORY PROPERTIES OF AQUEOUS EXTRACT OF WALNUT (JUGLANS REGIA L.) SEEDS

75%

Przekora A., Belcarz A., Kowalczyk K., Wójcik M., Wojciechowska K., Ginalska G.

Acta Poloniae Pharmaceutica - Drug Research

|

2018

|

vol. 75

|

issue 5

1167-1176

EN

Walnut (Juglans regia L., fam. Juglandaceae) fruit is found to be very rich in phenolic compounds and thus to show wide spectrum of biological activities like antioxidant, anti-inflammatory, or antitumour properties. Ethanol or methanol are preferentially used for preparation of walnut extracts for cosmetic applications. However, it is commonly known that alcohol causes dehydration and redness of the skin. The aim of this work was to prepare aqueous extract of undamaged walnut seeds rich in pellicles and to evaluate its antioxidant, anti-apoptotic, anti-inflammatory, and anti-aging properties in vitro. Conducted research clearly demonstrated that simple water extraction of undamaged kernels with pellicles allows to obtain rich in phenolic compounds (36-38 mg per g of lyophilisate) walnut extract, which protects fibroblasts and keratinocytes against oxidative stress induced by UVB dose of 35 mJ/cm2 (5-6-h exposure on a sunny day), protects keratinocytes against UVB-induced apoptotic death, limits the development of the inflammation in epidermis, and also possesses ability to inhibit collagenase and elastase. Thus, obtained aqueous walnut extract (at relatively low concentration of 5 µg/ml) is found to be a promising compound of sunscreen and anti-aging cosmetic formulations.

7

Diversity-Oriented Synthesis of Peptidomimetics: How and Why

63%

Wipf P.

Diversity Oriented Synthesis

|

2012

|

vol. 1

|

issue 1

EN

Based on oligopeptide sequences, structural diversity elements from side chain substitutions and backbone amide modifications are used for the preparation of bioactive peptide mimetics, including δ-amino-b,γ-alkenyl, δ-amino-b,γ-cyclopropyl, and γ-amino-a,b-cyclopropyl dipeptide isosteres. The hybrid molecule XJB-5-131 is composed of an alkene dipeptide isostere, a regular tripeptide sequence extracted from the cyclodecapeptide antibiotic gramicidin S (GS), and the free radical scavenger 4-AT. This agent is highly enriched in mitochondria, and, among other positive functions in cells and animal models, it has demonstrated efficacy in improving neurocognitive outcome after traumatic brain injury in rats. It slows down the aging phenotype in Ercc1 progeria models and reduces oxidative damage to mitochondrial DNA, enhancing neuronal survival and improving mitochondrial function in a mouse model of Huntington’s disease. The shortened alkene dipeptide isostere JP4-039 also folds into a b-turn secondary structure in the solid state and mediates several desired physiological and cell-protective effects, including radiation damage prevention and mitigation.

8

Metal oxide particles catalyze photo-oxidation in environmental media

63%

Minelli C., Tantra R.

Nanomaterials and the Environment

|

2013

|

vol. 1

40-47

EN

Metal oxide particles in the submicron and nanometer range endow a wide range of consumer products with unique properties. The widespread use of such products raises concerns on potential toxicity of these materials to man and the environment. Besides their size, the photo-catalytic properties of metal oxide particles are of particular concern. By utilizing molecular probes with tailored optical properties, we investigated the photo-catalytic properties of seven TiO2 (anatase), ZnO and CeO2 manufactured particles in environmental media. Controlled experiments confirmed that the particles catalyzed photo-oxidation and photo-production of reactive oxygen species (ROS), while no ROS generation was observed when the ionic form of the materials was used in place of the particles. While affecting their aggregation and sedimentation, the type of media was not found to strongly influence the photo-catalytic behavior of the particles. Within the size range that was investigated, ZnO particles resulted in the highest production of ROS, while anatase particles possessed the highest oxidative ability. Possible explanations of such behavior are suggested.

Refine search results

Role of antioxidant vitamins administration on the oxidative stress

Consequence of hydrogen atom abstraction from 5’-hydroxyl group of 2’-deoxyadenosine. Theoretical quantum mechanics study

Antioxidative responses to seasonal changes and chemiluminescence assay of Astragalus onobrychis leaves extract

The difference in stability between 5′R and 5′S diastereomers of 5′,8-cyclopurine-2′-deoxynucleosides. DFT study in gaseous and aqueous phase

DNA-based biosensors with external Nafion and chitosan membranes for the evaluation of the antioxidant activity of beer, coffee, and tea

UVB PROTECTIVE, ANTI-AGING, AND ANTI-INFLAMMATORY PROPERTIES OF AQUEOUS EXTRACT OF WALNUT (JUGLANS REGIA L.) SEEDS

Diversity-Oriented Synthesis of Peptidomimetics: How and Why

Metal oxide particles catalyze photo-oxidation in environmental media