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Search Results: 1 - 10 of 6965 matches for " free radical "
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Studies of the Relationship between Structure and Antioxidant Activity in Interesting Systems, Including Tyrosol, Hydroxytyrosol Derivatives Indicated by Quantum Chemical Calculations  [PDF]
Rogaie Rezaei-Sadabady, Nosratollah Zarghami, Abolfazl Barzegar, Akram Eidi, Abolfazl Akbarzadeh, Mustafa Rezaei-Tavirani
Soft (Soft) , 2013, DOI: 10.4236/soft.2013.23004
Abstract:

In nature, tyrosol (TY) and hydroxytyrosol (HT) are found in olive leaves which are for medical aims, with immune stimulant and antibiotic properties as well as the ability to be used for the treatment of neurodegenerative diseases such as Alzheimer. This ability of phytochemical TY and HT compounds are mainly believed to be of higher radical scavenging potential with effective antioxidant properties. In order to establish the possible structure-antioxidant activity relationship of tyrosol, hydroxytyrosol, hydroxytyrosol acetate and two designed hydroxytyrosol derivatives were studied by the help of quantum chemical calculations. The molecular electronic properties such as heat formation of the neutral, radical and orbitals energies were calculated as descriptors to predict the H atom donating abilities of compounds. Considering the results from the calculated descriptors, the derivatives having OH group substitutions in position number four of the aromatic ring can be classified highly active and better antioxidant compound. Therefore, the designed hydroxytyrosol derivatives showed most active feasible H atom donation. This work can be useful to design novel antioxidants.

Entropy, Free Radical and Life System  [PDF]
Honghu Li, Junhua Hou
Open Journal of Biophysics (OJBIPHY) , 2016, DOI: 10.4236/ojbiphy.2016.64009
Abstract: Effects of entropy and free radical in life system are elucidated. The results indicate that living organism can maintain normal activities only if a suitable free radicals inside living organism can be guaranteed. Excessive free radical should be eliminated to reduce entropy in living organism. Some ways provided to eliminate excessive free radical, reduce entropy and keep health.
Anti-oxidant activity and cytotoxicity of ethanolic extracts from rhizome of Musa acuminata  [PDF]
KPS Adinarayana, P Ajay Babu
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.34037
Abstract: In the present study, antioxidant activities of rhizome of Musa acuminata were investigated. Free radical scavenging assay (DPPH) and reducing power of the ethanolic extract of banana rhizome resulted in potential antioxidant activities. A relatively high percentage of antioxidant activity by DPPH assay (81.41% at 200 μg/ml) which was comparable to that of the standard, ascorbic acid at 100 μg/ml was observed. With the gallic acid as standard the extract showed a relatively low reductive potential, however, when tested for cytotoxicity at the highest concentration of the tested dose (256 μg/ml), the maximum rate of inhibition observed was 50.32%. The present work indicates that the ethanolic extract of Musa acuminata exhibits significant antiproliferative and antioxidant activities.
Comparative Analysis of the Antioxidant and Free-Radical Scavenging Activities of Different Water-Soluble Extracts of Green, Black and Oolong Tea Samples  [PDF]
Jesús Tejero, Sara Gayoso, Irma Caro, Damián Cordoba-Diaz, Javier Mateo, José E. Basterrechea, Tomás Girbés, Pilar Jiménez
Food and Nutrition Sciences (FNS) , 2014, DOI: 10.4236/fns.2014.522228
Abstract: Extracts of 40 green, black or oolong high quality tea samples from China, Japan or India among others, have been prepared according to the manufacturer instructions and assayed for total polyphenols content using the Folin-Ciocalteu phenol reagent. In addition, the antioxidant activity was assessed by the CUPRAC method and the free-radical scavenging activity was determined using the antioxidant-promoting decay of the stable free-radical DPPH. Caffeine and the most important catechins were identified using RP-HPLC previously validated method. Results from this study suggest that teas, even though they content similar amounts of caffeine, differ considerably in polyphenolic content and therefore in antioxidant and free-radical scavenging activities, depending on the part of the plant used and the process applied to the material for the preparation of the final tea presentation. Correlations among Folin-Ciocalteau’s reactivity of tea samples, the neocuproine reactivity, the DPPH decolourization and the HPLC analysis suggest that the antioxidant activity is due essentially to polyphenolic compounds present in teas, mainly EGCG. The best extraction method of tea powder was the one indicated by dealers. In general, the richest samples belong to green teas and the poorest samples belong to the black teas.
Iodine—A Potential Antioxidant and the Role of Iodine/Iodide in Health and Disease  [PDF]
Rudolf Winkler
Natural Science (NS) , 2015, DOI: 10.4236/ns.2015.712055
Abstract: In human physiology, iodine is primarily noted for its role in thyroid function and less so for its many extrathyroidal functions, particularly those based on its antioxidant properties. As I- it protects against free radicals and peroxides. This is seen in vitro in decreased depolymerization of hyaluronic acid and increased antioxidant status in human serum, and in vivo in increased antioxidant enzyme activities and decreases of malondialdehyde and peroxides. It could be shown or deduced that balneotherapeutic applications of iodine/iodide have a positive effect on cardiocirculatory diseases, respiratory disorders, some eye diseases (dry eye, cataract, age-related macular degeneration), and other degenerative diseases connected with increased oxidative stress that are also treated by balneotherapy.


PHOTOCHEMICAL INTERACTIONS BETWEEN NITROXIDE FREE RADICALS AND BACTERIORHODOPSIN IN SOLUTION

科学通报(英文版) , 1991,
Abstract:
COMPARISON OF PHARMACOLOGICAL SCREENING OF CNS DEPRESSANT ACTION OF FUSED RING HETEROCYCLIC ADDUCT WITH FUSED RING AROMATIC WITH BENZODIAZEPINE AS STANDARD
RAJALAKSHMI PADMA VAIRAVASUNDARAM1*., KALAISELVI SENTHIL2
International Journal of Drug Development & Research , 2010,
Abstract: Flavonoids compounds have anti-oxidation properties in that they remove free radicals, reduce blood pressureand reduce vessel thrombosis. So many extraction methods are available, but the selection of specific solventsystem for the separation and quantification of quercetin is important. It can be easily analyzed bychromatographic methods, but before testing a new type of plant material it is opportune to optimizechromatographic conditions. The aim of this study is to optimize the chromatographic conditions in TLC offlavonoids, as standard compounds that may be present in Euphorbia hirta. We compared 10 dif erent mobilephases, to find the most appropriate mobile phase. The results showed that the optimal extract
Scavenging radical kinetic and Antianaemic Screening Properties of some Medicinal Plants used in Cameroon
NP C Biapa,J E Oben,J Y Ngogang
International Journal of Applied Research in Natural Products , 2011,
Abstract: Summary: Amphimas pterocaroides, Harungana madagascariensis, Myrianthus arboreus and Cussonia barteri which are medicinal plants commonly used in Cameroon for the management or reversal of anaemia, were screened for their scavenging radical kinetic and the antianaemic properties. The scavenging radical kinetic was defined as the inhibition rate of DPPH (2, 2-diphenyl-2-picrylhydrazyl hydrate) using methanolic extract of each plant. The antianaemic property of fractions was also evaluated by measuring the haemoglobin (Hb), red blood cell (RBC) and haematocrit (HCT) levels. A. pterocarpoides and M. arboreus inhibits the DPPH rapidly with time and dose. The total inhibition of A. pterocarpoides was successful at 90 min with the concentration of 0.5 mg / ml and at 30 min when 2 mg / ml was used. M. arboreus and H. madagascariensis and C. barteri have presented their total inhibition at 60 min, 90 min and 180 min respectively. Though all plant fractions tested gave an increase in the content of Hb, RBC and HCT, the increase was most rapid for the hydroethanolic extract of H. madagascariensis. The presence of active phytochemical substances with antioxidant activities may provide a substantial basis for the use of these plants in ethnomedicine. Industrial relevance: Our extracts have free radical scavengers that act by intermediate kinetics. Our extracts have free radical scavengers that act by intermediate kinetics. The bioactive compounds of these plants could be isolated and synthesized. This industrial synthesis could intensify the products and allow it availability to cure anaemia for the development. These extract can also be useful to the food and agricultural industry for the conservation of product due to their capacity to eradicate free radicals with a slow or intermediate kinetic.
The Study of Influence of Silica and Polyethilene Glycols Organic-Inorganic Compounds on Free-Radical Processes in Vitro  [PDF]
Olga G. Sitnikova, Sergey B. Nazarov, Irina V. Shikhanova, Alexander V. Agafonov, Jean A. Dyuzhev, rina G. Popova
Pharmacology & Pharmacy (PP) , 2010, DOI: 10.4236/pp.2010.12010
Abstract: In this study investigation of influence of hybrid nanosilica-polyethylene glycols materials (molecular weight 1500, 6000 and 15000), prepared by sol-gel synthesis, on lipid peroxidation and antioxidant activity of human serum in vitro was performed. Methods included chemiluminescence analysis and quantitative malonic dialdehyde estimation. It was revealed that nanosilica-PEG materials with different molecular weight had certain biological activity. Powders of SiO2-PEG 1500 and SiO2-PEG 6000 manifest prooxidant effects, whereas mesoporous (calcine) powders produced antioxidant effects in blood serum in vitro.
Effect of calcium and diltiazem on phenylhydrazine-induced oxidative injury in goat erythrocytes  [PDF]
Kaushik Das, Jharna Bhattacharyya
Health (Health) , 2010, DOI: 10.4236/health.2010.210181
Abstract: Lipid peroxidation, hemolysis and thiol contents were studied in intact goat erythrocytes exposed to phenylhydrazine. An increase in lipid peroxidation, hemolysis and thiol content was observed after phenylhydrazine treatment of erythrocyte. Extracellular Ca2+ potentiates the phenylhydrazine-induced lipid peroxidation and hemoly- sis of erythrocytes significantly. Ca2+ does not influence much the thiol content of phenylhydrazine treated erythrocytes. No effect of Ca2+ on control lipid peroxidation, hemolysis and thiol contents of erythrocytes was observed. Diltiazem and EDTA inhibited the increased responses of lipid peroxidation and hemolysis due to Ca2+. However the thiol content was not much influenced by either diltiazem or EDTA. The results suggest that oxidative damage of erythrocyte caused by phenyl hydrazine could be prevented by calcium channel antagonist, diltiazem, which may act as antioxidant also.
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