Evidence of Trolox and some gallates as synergistic protectors of erythrocytes against peroxyl radicals

1998 ◽  
Vol 76 (4) ◽  
pp. 661-664 ◽  
Author(s):  
J Wu ◽  
H Sugiyama ◽  
L -H Zeng ◽  
D Mickle ◽  
T -W Wu
Keyword(s):  
Antioxidant Activity ◽  
Vitamin E ◽  
Protective Effect ◽  
Propyl Gallate ◽  
Peroxyl Radical ◽  
Human Erythrocytes ◽  
Peroxyl Radicals ◽  
Methyl Ethyl ◽  
Radical Initiator ◽  
Individual Contributions

The peroxidation of human erythrocytes induced by peroxyl radical initiator and its inhibition by several gallate esters (e.g., propyl, methyl, ethyl) and Trolox (a more polar analogue of vitamin E) have been studied. The antioxidant activity was determined on erythrocytes against hemolysis generated by a thermal activator, 2,2prime-azobis-(2-amidinopropane)dihydrogenchloride. It was found that propyl gallate and its two analogues were more effective than Trolox in preventing cell lysis. However, the combination of gallate esters and Trolox produced a protective effect exceeding the arithmetic sum of their individual contributions. These perceived synergisms occur at more than one level of Trolox at a given level of a gallate ester.Key words: Trolox, gallates, synergism, peroxyl radicals.

The β-carotene dilemma: ESR study with coordinated peroxyl radicals

2006 ◽  
Vol 60 (3) ◽  
Author(s):  
A. Tkáč ◽  
G. Scott
Keyword(s):  
Vitamin E ◽  
Peroxyl Radical ◽  
Cell Damage ◽  
Transition Metal Ions ◽  
Spin Trapping ◽  
Peroxyl Radicals ◽  
Polar Solvents ◽  
Primary Attack ◽  
Peroxy Group ◽  
Β Carotene

AbstractThe apparently unpredictable behaviour of β-carotene in the supplementation of the diet of smokers is discussed in the light of the reactions of peroxyl radicals with β-carotene in the absence of oxygen. The decay of tert-butylperoxyl radicals in the presence of β-carotene was studied at ambient temperature in non-polar solvents by ESR spectroscopy. The primary reaction in the absence of oxygen is interpreted as a spin-trapping effect of a peroxyl radical by β-carotene producing an intermediate labile free radical, which disappears after recombination with a second tert-butylperoxyl radical. The result is the transformation of β-carotene to a diamagnetic compound with two peroxy bonds. In the presence of chelating transition metals with unpaired d-electrons as electron donors the peroxy group of the oxidized β-carotene can be split to alkoxyl free radicals. The primary attack of tert-butylperoxyl radicals is completely inhibited in the presence of vitamin E followed by production of free aryloxy radicals and the presence of oxygen has no significant effect on this reaction. Spin-trapping of peroxyl radicals by the double bond of vitamin A leads to its oxidation in the absence of vitamin E.Transition metal ions such as Co, Cr, Fe, and Mn, known to be present in the aerosol of cigarette smoke, homolyse the peroxyl bonds of peroxidised β-carotene, which results in cell damage.

Is the Oxygen Radical Absorbance Capacity (ORAC) Method a Peroxyl-radical Scavenging Assay?

2010 ◽  
Vol 224 (06) ◽  
pp. 921-928 ◽  
Author(s):  
Yoshimi Sueishi ◽  
Daisuke Yoshioka ◽  
Shigeru Oowada ◽  
Nobuyuki Endoh ◽  
Shunji Kohri ◽  
...  
Keyword(s):  
Peroxyl Radical ◽  
Radical Scavenging Activity ◽  
Aqueous Media ◽  
Radical Scavenging ◽  
Spin Trapping ◽  
Oxygen Radical ◽  
Water Soluble ◽  
Oxygen Radical Absorbance Capacity ◽  
Peroxyl Radicals ◽  
Radical Initiator

AbstractThe oxygen radical absorbance capacity (ORAC) method employs a water soluble azo-radical initiator, AAPH (2,2’-azobis(2-amidinopropane) dihydrochloride) as a free radical generator, by which the fluorescent probe fluorescein is damaged to result in the loss of fluorescence. Antioxidants can protect the probe from the damage and the degree of protection is quantified. Because AAPH has been used as a lipid-peroxidation reagent, “oxygen radical” in ORAC is generally accepted as peroxyl radicals; however, in the present spin trapping experiments using a newly developed spin trap, CYPMPO, there was no indication of peroxyl-radical formation in AAPH decomposition in aqueous media. These spin trapping studies demonstrated that alkoxyl (RO·) radical adduct was the sole product of AAPH decomposition. In contrast, alkyl-peroxyl (ROO·) radical was spin-trapped during the decomposition of a lipid soluble azo-radical initiator AIBN (azobis(isobutyronitrile)) in non-aqueous media. We speculate that alkyl-peroxyl radicals are short-lived in water, rapidly converted into alkoxyl radicals. Although the possibility that ORAC method monitors peroxyl-radical scavenging activity cannot be completely eliminated, spin trapping evidence strongly indicates that ORAC method is a scavenging capacity assay for alkoxyl radicals.

scholarly journals In vitro antioxidant activity of olive leaf extract (Olea europaea L.) and its protective effect on oxidative damage in human erythrocytes

Heliyon ◽  
2018 ◽  
Vol 4 (9) ◽  
pp. e00805 ◽  
Author(s):  
Patricia Goldschmidt Lins ◽  
Silvana Marina Piccoli Pugine ◽  
Antonio Márcio Scatolini ◽  
Mariza Pires de Melo
Keyword(s):  
Antioxidant Activity ◽  
Oxidative Damage ◽  
Protective Effect ◽  
Leaf Extract ◽  
Human Erythrocytes ◽  
Olive Leaf ◽  
Olea Europaea L ◽  
Olive Leaf Extract ◽  
In Vitro Antioxidant Activity

Protective Effect of Vitamin E on Immune Triggered, Granulocyte Mediated Endothelial Injury

1984 ◽  
Vol 51 (01) ◽  
pp. 089-092 ◽  
Author(s):  
M A Boogaerts ◽  
J Van de Broeck ◽  
H Deckmyn ◽  
C Roelant ◽  
J Vermylen ◽  
...  
Keyword(s):  
Vitamin E ◽  
Protective Effect ◽  
Umbilical Vein ◽  
Endothelial Damage ◽  
Endothelial Injury ◽  
Mediated Effects ◽  
Anti Oxidant ◽  
Endothelial Cell Cultures ◽  
Vitro Model

SummaryThe effect of alfa-tocopherol on the cell-cell interactions at the vessel wall were studied, using an in vitro model of human umbilical vein endothelial cell cultures (HUEC). Immune triggered granulocytes (PMN) will adhere to and damage HUEC and platelets enhance this PMN mediated endothelial injury. When HUEC are cultured in the presence of vitamin E, 51Cr-leakage induced by complement stimulated PMN is significantly decreased and the enhanced cytotoxicity by platelets is completely abolished (p <0.001).The inhibition of PMN induced endothelial injury is directly correlated to a diminished adherence of PMN to vitamin E- cultured HUEC (p <0.001), which may be mediated by an increase of both basal and stimulated endogenous prostacyclin (PGI2) from alfa-tocopherol-treated HUEC (p <0.025). The vitamin E-effect is abolished by incubation of HUEC with the irreversible cyclo-oxygenase inhibitor, acetylsalicylic acid, but the addition of exogenous PGI2 could not reproduce the vitamin E-mediated effects.We conclude that vitamin E exerts a protective effect on immune triggered endothelial damage, partly by increasing the endogenous anti-oxidant potential, partly by modulating intrinsic endothelial prostaglandin production. The failure to reproduce vitamin E-protection by exogenously added PGI2 may suggest additional, not yet elucidated vitamin E-effects on endothelial metabolism.

Isomerization of the Isoprene Hydroxy Nitrates and Formation of Orthonitrite Compounds

2019 ◽  
Author(s):  
Gabriel da Silva
Keyword(s):  
Hydroxy Group ◽  
Peroxyl Radical ◽  
Branching Fractions ◽  
Membered Ring ◽  
Low Energy ◽  
Peroxyl Radicals ◽  
Aerosol Formation ◽  
Subsequent Removal ◽  
Ring Compounds ◽  
Group Migration

Atmospheric oxidation of isoprene produces significant yields of eight unique nitrate 11 compounds, each with a β- or δ-hydroxy group. These isoprene hydroxy nitrates (ISOPNs) 12 significantly impact upon global NOx budgets, O3 levels, and aerosol formation. 13 Uncertainties exist, however, in our understanding of ISOPN chemistry, particularly in their 14 yields from the reaction of isoprene peroxyl radicals with NO. This study describes novel 15 isomerization reactions of the ISOPNs, identified through the application of computational 16 chemistry techniques. These reactions produce saturated polycyclic orthonitrite compounds 17 via attack of the R–NO2 group on the vinyl moiety. For the δ-hydroxy nitrates, low-energy 18 isomerization pathways exist to six-membered ring compounds that are around 5 kcal mol-1 19 exothermic. These reactions proceed with barriers around 15 kcal mol-1 below the 20 respective peroxyl radical + NO reactants and yield orthonitrites that can further isomerize 21 to β-hydroxy ISOPNs. Moreover, the δ-hydroxy nitrates can directly interconvert with their β 22 substituted counterparts via NO3 group migration, with barriers that are lower yet. It follows 23 that β-hydroxy nitrates may be stabilized in the δ-hydroxy form, and vice versa. Moreover, 24 the lowest-energy pathway for dissociation of the δ-hydroxy ISOPNs is for the formation of 25 β-hydroxy alkoxyl radicals, and because of this established branching fractions between the 26 various isoprene peroxyl radicals may require re-evaluation. The results presented here also 27 suggest that ISOPNs may be stabilized to some extent in their saturated orthonitrite forms, 28 which has implications for both the total nitrate yield and for their subsequent removal by 29 OH, O3, and photolysis.<br><br>

Antioxidant Activity and Protective Effect against Oxidative Stress on Hippocampal HT22 Cells of Tea Seed Oil

2018 ◽  
Vol 24 (1) ◽  
pp. 53-59
Author(s):  
Jong Min Kim ◽  
Seon Kyeong Park ◽  
Jin Yong Kang ◽  
Seong-kyeong Bae ◽  
Ga-Hee Jeong ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Activity ◽  
Protective Effect ◽  
Seed Oil ◽  
Ht22 Cells ◽  
Tea Seed Oil

scholarly journals Anti-Aging Potential of Extracts from Washingtonia filifera Seeds

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 151
Author(s):  
Benedetta Era ◽  
Sonia Floris ◽  
Valeria Sogos ◽  
Clara Porcedda ◽  
Alessandra Piras ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Protective Effect ◽  
Pharmaceutical Preparation ◽  
Human Keratinocytes ◽  
Inhibitory Effect ◽  
Skin Aging ◽  
Stressed Cells ◽  
Collagenase Inhibition ◽  
Washingtonia Filifera ◽  
Seed Extracts

The aim of this study was to test the inhibitory effect of fruit extracts from Washingtonia filifera on skin aging-related enzymes. The pulp extracts did not exert a significant enzyme inhibition while seed extracts from W. filifera exhibit anti-elastase, anti-collagenase, and anti-tyrosinase activities. Tyrosinase was mildly inhibited while a stronger effect was observed with respect to elastase and collagenase inhibition. Alcoholic extracts provided better results than aqueous extracts. Among them, methanol extracts showed the prominent enzyme inhibitory activities being IC50 value for elastase and collagenase comparable and even better than the reference compound. The inhibition mode of the most active extracts was investigated by Lineweaver-Burk plot analysis. Seed extracts from W. filifera were also investigated for their photo-protective effect by Mansur equation and the antioxidant activity of W. filifera extract was evaluated in oxidative-stressed cells. To evaluate the safety of the extract, the effect on cell viability of human keratinocytes cells was analyzed. Methanol extract presented the best photo-protective effect and exerted an antioxidant activity in a cellular system with no cytotoxic effect. The overall results demonstrate that W. filifera extracts are promising sources of bioactive compounds that could be used in cosmetic and pharmaceutical preparation.

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