ChemInform Abstract: MECHANISMS OF ANTIOXIDANT ACTION, ANTIOXIDANT ACTIVITY OF PRODUCTS DERIVED FROM O-PHENYLENE PHOSPHITES

1974 ◽  
Vol 5 (33) ◽  
pp. no-no
Author(s):  
KENNETH J. HUMPHRIS ◽  
GERALD SCOTT
Keyword(s):  
Antioxidant Activity ◽  
Antioxidant Action

Natural Antioxidants in Hevea Latex

1948 ◽  
Vol 21 (3) ◽  
pp. 752-764 ◽  
Author(s):  
R. F. A. Altman
Keyword(s):  
Amino Acids ◽  
Antioxidant Activity ◽  
Water Layer ◽  
Natural Antioxidants ◽  
Antioxidant Action ◽  
Active Components ◽  
Naturally Occurring ◽  
Increasing Demand ◽  
Low Nitrogen ◽  
Soluble Fractions

Abstract An elaborate investigation on the identity and usefulness of the antioxidants naturally occurring in Hevea latex is of value because there is an increasing demand for special types of rubber with low nitrogen and ash contents, less water absorption, better electrical properties, and less odor than common crepe, and because these rubbers are generally unstable in comparison with the usual grades of rubber crepe and sheet. for the purpose of the investigation, fresh latex was separated into main-fractions, the most important of which have been called water-solubles and ether-solubles. These were further separated into various subfractions, which, one by one, have been tested for their antioxidant activity on raw rubber. In the following table only those fractions which show an outstanding antioxidant action are recorded. It is shown further that the amino acids are most remarkable in their antioxidant action : minute quantities exert a strong retarding action on the oxidation of raw rubber. Choline and cephaline are most probably the active components of the second water layer. The active ether-soluble fractions could not be identified due to the small quantities separated.

Mechanisms of Antioxidant Action: The Antioxidant Activity of “Spin-Traps” in Rubber

1984 ◽  
Vol 57 (4) ◽  
pp. 779-791 ◽  
Author(s):  
L. P. Nethsinghe ◽  
G. Scott
Keyword(s):  
Antioxidant Activity ◽  
Mechanism Of Action ◽  
Nitroxyl Radicals ◽  
Antioxidant Action ◽  
Spin Traps ◽  
Phenolic Group ◽  
Stable Phenoxyl ◽  
High Level

Abstract A number of nitrones containing a partially hindered phenolic group are shown to be effective antidegradants for sulfur vulcanized rubbers. They exhibit a high level of antiozonant and antifatigue activity, but unlike commercial antiozonants they do not cause discoloration of light colored formulations. The new antidegradants are less effective than conventional additives as thermal antioxidants, but their performance as antifatigue agents and antioxidants is augmented by their use in combination with nonstaining antioxidants. The mechanism of action of the phenolic nitrones is believed to involve their oxidation to stable phenoxyl/nitroxyl radicals.

scholarly journals UV-effects on antioxidant activity of selected carotenoids in the presence of lecithin estimated by DPPH test

2008 ◽  
Vol 73 (11) ◽  
pp. 1051-1061 ◽  
Author(s):  
Dragan Cvetkovic ◽  
Dejan Markovic
Keyword(s):  
Antioxidant Activity ◽  
Ultraviolet Radiation ◽  
Energy Input ◽  
High Energy ◽  
Antioxidant Action ◽  
Dpph Radical ◽  
Dpph Test ◽  
Uv Photons

The effects of ultraviolet radiation (UV) on the antioxidant action of three selected carotenoids (?-carotene, lycopene and lutein) in the presence of a lipoidal lecithin mixture were studied by the DPPH (1,1-diphenyl-2-picrylhydrazyl) test. The test is based on the measurement of the decrease of the free DPPH radical absorbance at 517 nm caused by the antioxidant action of carotenoids, which appeared to be strongly affected by UV-action. The high-energy input of the involved UV-photons plays a major governing role.

EVALUATION OF ANTIOXIDANT ACTIVITY BY STABILIZATION OF VITAMIN A AND CAROTENE

1950 ◽  
Vol 28f (6) ◽  
pp. 157-165 ◽  
Author(s):  
H. J. Lips ◽  
W. D. McFarlane
Keyword(s):  
Antioxidant Activity ◽  
Vitamin A ◽  
Ultraviolet Irradiation ◽  
Wheat Germ ◽  
Mineral Oil ◽  
Ethylene Dichloride ◽  
Antioxidant Action ◽  
Accelerated Tests ◽  
Wheat Germ Oil ◽  
General Evaluation

Accelerated tests for antioxidant activity are described which depend on the protection of vitamin A concentrates (in ethylene dichloride solution) against ultraviolet irradiation, and on the protection of carotene (in mineral oil solution) against heat and aeration. The protection of vitamin A was influenced by light-filtering effects; the carotene method appeared to be more generally useful. The stabilizing power of wheat-germ oil for both solutions of Vitamin A and carotene against light is partly due to a screening effect by pigments. Some of the protection is also due to other components of the wheat-germ oil, but it is not known whether these function as stabilizers against light according to the usual theories of antioxidant action. Light-accelerated decomposition of vitamin A and carotene appeared more suitable for special tests than for general evaluation of antioxidants; stability experiments in the absence of light gave a more generally applicable picture of antioxidant activity.

Mechanisms of antioxidant action: the antioxidant activity of nitrones in polypropylene

1985 ◽  
Vol 30 (8) ◽  
pp. 3267-3281 ◽  
Author(s):  
Khirud B. Chakraborty ◽  
Gerald Scott ◽  
Hassan Yaghmour
Keyword(s):  
Antioxidant Activity ◽  
Antioxidant Action

Study on antioxidant activity of certain plants in Thailand: Mechanism of antioxidant action of guava leaf extract

2007 ◽  
Vol 103 (2) ◽  
pp. 381-388 ◽  
Author(s):  
Suganya Tachakittirungrod ◽  
Siriporn Okonogi ◽  
Sombat Chowwanapoonpohn
Keyword(s):  
Antioxidant Activity ◽  
Leaf Extract ◽  
Antioxidant Action ◽  
Guava Leaf

scholarly journals Estudo Da Atividade Antioxidante Do Óleo Essencial De Alecrim (Rosmarinus Officinalis L) No Tratamento Ao Estresse Oxidativo Na Doença De Alzheimer

2022 ◽  
Vol 2 (3) ◽  
pp. 238-246
Author(s):  
Letícia Grejo de Oliveira ◽  
Mary Leiva de Faria ◽  
Elaine Soares Amorim
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Activity ◽  
Essential Oil ◽  
Antioxidant Capacity ◽  
Antioxidant Action ◽  
Radical Method ◽  
Rosmarinus Officinalis L ◽  
Hydrolysis Of ◽  
Reduction Capacity ◽  
Rosemary Essential Oil

O óleo essencial de alecrim (Rosmarinus offininalis L) pode ser utilizado na prevenção do Alzheimer em decorrência da sua composição química, especialmente compostos terpênicos que atuam pela sua ação antioxidante ou pela inibição da acetilcolinesterase (AChE), que retarda a hidrólise catabólica da acetilcolina com o intuito de compensar a escassez da mesma nos terminas sinápticos. Esse trabalho teve o objetivo de extrair e determinar a atividade antioxidante do óleo essencial de alecrim. Primeiramente extraiu-se o óleo essencial do material botânico de alecrim por hidrodestilação em destilador do tipo Clevenger. A determinação da capacidade antioxidante foi realizada em triplicata pelo método de radical livre utilizando o reagente 2,2-difenil-1-picril hidrazil (DPPH). O rendimento obtido na extração do óleo essencial de alecrim foi de 0,42%. O resultado obtido para a atividade antioxidante do óleo essencial de alecrim foi satisfatório, sendo a capacidade de redução de DPPH em 30 minutos de 87,21%±0,25. Os resultados obtidos indicam que o óleo essencial de alecrim pode ser utilizado no tratamento da doença de Alzheimer, visto que o mesmo pode atuar inibindo o stress oxidativo, a principal causa para o desenvolvimento de doenças neurodegenerativas. Deve-se considerar, entretanto, a composição do óleo essencial visto que os fatores ambientais e de cultivo podem influenciar na capacidade antioxidante do mesmo.   Rosemary essential oil (Rosmarinus offininalis L) can be used in the prevention of Alzheimer's due to its chemical composition, especially terpenic compounds that act by its antioxidant action or by the inhibition of acetylcholinesterase (AChE), which delays the catabolic hydrolysis of acetylcholine in order to compensate the lack of it in the synaptic terminals. This work aimed to extract and determine the antioxidant activity of rosemary essential oil. First, the essential oil was extracted from the rosemary botanical material by hydrodistillation in a Clevenger distiller. The antioxidant capacity was determined in triplicate by the free radical method using the reagent 2,2-diphenyl-1-picryl hydrazyl (DPPH). The yield obtained from the extraction of rosemary essential oil was 0.42%. The result obtained for the antioxidant activity of rosemary essential oil was satisfactory, and the DPPH reduction capacity in 30 minutes was 87.21%±0.25. The results obtained indicate that rosemary essential oil can be used in the treatment of Alzheimer's disease, since it can act by inhibiting oxidative stress, the main cause for the development of neurodegenerative diseases. However, the composition of the essential oil should be considered, since environmental and cultivation factors can influence its antioxidant capacity.  

scholarly journals Antioxidant Potential of Novel Designed Phenolic Derivatives: Computational Insights

2020 ◽  
Vol 14 (4) ◽  
pp. 448-454
Author(s):  
Dinesh R. Pandithavidana ◽  
◽  
Kushani S. K. Hewage ◽  
Keyword(s):  
Density Functional Theory ◽  
Antioxidant Activity ◽  
Phenolic Compounds ◽  
Electron Donor ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Antioxidant Action ◽  
Functional Theory ◽  
Primary Antioxidant ◽  
Phenolic Derivatives

Density functional theory calculations were applied for designed phenolic antioxidant derivatives. The reaction enthalpies related to various mechanisms of primary antioxidant action were deliberated in detail. How antioxidant activity of designed phenolic compounds has been perturbed by electron donor and withdrawing substituents present at ortho, meta and para positions, allylic conjugation and the dimerization effect were computed.

scholarly journals The Antioxidant Activity of Tobacco Smoke

1975 ◽  
Vol 8 (1) ◽  
Author(s):  
J. Johnson ◽  
M. A. Nisbet
Keyword(s):  
Antioxidant Activity ◽  
Tobacco Smoke ◽  
Antioxidant Activities ◽  
Vapour Phase ◽  
Rate Of Change ◽  
Peroxy Radicals ◽  
Antioxidant Action ◽  
Oxidative Destruction ◽  
Coupled Reaction ◽  
Pipe Tobacco

AbstractCigarette smoke has been shown to contain free radicals in both the vapour and particulate phases. The present investigation was undertaken to find out whether these radicals could initiate or promote the formation of radical peroxides which might in turn lead to lipid peroxidation. To investigate this, a system involving the coupled oxidation of b-carotene and linoleic acid was utilized. In this coupled reaction, b-carotene is destroyed through oxidation by free peroxy radicals. The system can therefore be used as a convenient detector of auto-oxidative mechanisms in which peroxide radicals participate, as well as provide an assay for antioxidants, since in their presence oxidative destruction of b-carotene is blocked. Our results show that smoke did not contribute to the oxidative destruction of b-carotene but rather behaved as an antioxidant. Both smoke vapour and particulate matter were found to be highly antioxidant. A number of pure vapour phase components were tested and the bulk of antioxidant activity was found to be due to HCN. Smoke condensates from different tobacco types were compared and differentiated according to their relative efficiencies of antioxidant activities. For comparison, units of antioxidant activity were expressed as rate of change of optical density with time. The highest antioxidant activities were obtained with air-, flue-cured (cut) and perique tobaccos. Pipe tobacco had the least activity while cigar and flue-cured (granulated), stem and sheet tobaccos had intermediate values. Tests done on smoke fractions derived from the fractionation of total condensate revealed that antioxidant activity resided largely in the neutral and water-insoluble acid fractions with virtually no activity in the basic fractions. The mode of antioxidant action of tobacco smoke is discussed in terms of free-radical mechanisms.

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