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Scavenging effect of melatonin on hydroxyl radicals generated by alloxan
Author(s) -
Brömme H.J.,
Mörke W.,
Peschke E.,
Ebelt H.,
Peschke D.
Publication year - 2000
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1034/j.1600-0633.2002.290402.x
Subject(s) - chemistry , melatonin , lipid peroxidation , glutathione , radical , reactive oxygen species , malondialdehyde , antioxidant , hydroxyl radical , biochemistry , liposome , endocrinology , biology , enzyme
Alloxan can act as a generator of reactive oxygen species (ROS) as long as sufficient suitable reducing agents (e.g. reduced glutathione) and oxygen are available. Using electron spin resonance‐spectroscopy and the oxygen‐centered spin trap DEPMPO, we demonstrate that hydroxyl radicals (OHzrad;) are formed in vitro by alloxan in the presence of glutathione (GSH) and chelated divalent iron. Furthermore, peroxidation of polyunsaturated fatty acids from phosphatidylcholine‐containing liposomes with concomitant formation of malondialdehyde (MDA) was used as a further indicator for a preceding OHzrad; formation. Melatonin, the main secretory product of the pineal gland, is an effective scavenger of OHzrad;. The 50%‐inhibitor concentration (IC50‐value) for melatonin to scavenge OHzrad; generated from the alloxan/GSH‐reaction in the presence of ferrous ions was 23 μmol/L. In contrast to the ability to effectively scavenge OHzrad;, the potential of melatonin to prevent lipid peroxidation is considerably less pronounced.