Antioxidant effect of 4-nerolidylcatechol and α-tocopherol in erythrocyte ghost membranes and phospholipid bilayers
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2013
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Resumo
4-Nerolidylcatechol (4-NC) is found in Pothomorphe umbellata root extracts and is reported to have a topical protective effect
against UVB radiation-induced skin damage, toxicity in melanoma cell lines, and antimalarial activity. We report a comparative
study of the antioxidant activity of 4-NC and a-tocopherol against lipid peroxidation initiated by two free radical-generating
systems: 2,29-azobis(2-aminopropane) hydrochloride (AAPH) and FeSO4/H2O2, in red blood cell ghost membranes and in egg
phosphatidylcholine (PC) vesicles. Lipid peroxidation was monitored by membrane fluidity changes assessed by electron
paramagnetic resonance spectroscopy of a spin-labeled lipid and by the formation of thiobarbituric acid-reactive substances.
When lipoperoxidation was initiated by the hydroxyl radical in erythrocyte ghost membranes, both 4-NC and a-tocopherol acted
in a very efficient manner. However, lower activities were observed when lipoperoxidation was initiated by the peroxyl radical;
and, in this case, the protective effect of a-tocopherol was lower than that of 4-NC. In egg PC vesicles, malondialdehyde
formation indicated that 4-NC was effective against lipoperoxidation initiated by both AAPH and FeSO4/H2O2, whereas atocopherol
was less efficient in protecting against lipoperoxidation by AAPH, and behaved as a pro-oxidant for FeSO4/H2O2.
The DPPH (2,2-diphenyl-1-picrylhydrazyl) free-radical assay indicated that two free radicals were scavenged per 4-NC
molecule, and one free radical was scavenged per a-tocopherol molecule. These data provide new insights into the antioxidant
capacity of 4-NC, which may have therapeutic applications for formulations designed to protect the skin from sunlight
irradiation.
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Electron paramagnetic resonance, 4-Nerolidylcatechol, Spin label, Lipid peroxidation, DPPH
Citação
FERNANDES, K. S.; SILVA, A. H. M.; MENDANHA, S. A.; REZENDE, K. R.; ALONSO, A. Antioxidant effect of 4-nerolidylcatechol and α-tocopherol in erythrocyte ghost membranes and phospholipid bilayers. Brazilian Journal of Medical and Biological Research, Ribeirão Preto, v. 46, n. 9, p. 780-788, Sept. 2013.