Antioxidant effect of 4-nerolidylcatechol and α-tocopherol in erythrocyte ghost membranes and phospholipid bilayers.
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 α-tocopherol against lipid peroxidation initiated by two free radical-generating systems: 2,2'-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 α-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 α-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 α-tocopherol 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 α-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.
Instituto de Física, Universidade Federal de Goiás, Goiânia,GO, Brasil.
K S
KS
Fernandes
A H M
AH
Silva
S A
SA
Mendanha
K R
KR
Rezende
A
A
Alonso
D000578:Amidines / Q000008:administration & dosage / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D002396:Catechols / Q000494:pharmacology*; D004578:Electron Spin Resonance Spectroscopy; D004910:Erythrocyte Membrane / Q000187:drug effects*; D005609:Free Radicals / Q000032:analysis; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008315:Malondialdehyde / Q000032:analysis; D010545:Peroxides / Q000032:analysis*; D010713:Phosphatidylcholines / Q000494:pharmacology; D010743:Phospholipids / Q000494:pharmacology*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018517:Plant Roots / Q000737:chemistry; D024502:alpha-Tocopherol / Q000494:pharmacology*
C110583:4-nerolidylcatechol; D000578:Amidines; D000975:Antioxidants; D002396:Catechols; D005609:Free Radicals; D010545:Peroxides; D010713:Phosphatidylcholines; D010743:Phospholipids; D010936:Plant Extracts; C049375:perhydroxyl radical; D008315:Malondialdehyde; C046728:2,2'-azobis(2-amidinopropane); D024502:alpha-Tocopherol