Abstract
Melatonin (N-acetyl-5-methoxytryptamine) and its immediate precursor N-acetyl serotonin in the metabolism of tryptophan are free radical scavengers that
have been found to protect against non-enzymatic lipid peroxidation in many experimental
models. By contrast, little is known about the antioxidant ability of these indoleamines
against NADPH enzymatic lipid peroxidation. The light emission produced by rat-liver
microsomes, expressed as total cpm during 180min of incubation at 37°C, was two-fold greater in the presence of ascorbate (0.4mM) when compared with NADPH (0.2mM). Maximal peaks of light emission produced by microsomes lipid peroxidized with
ascorbic-Fe2+ or NADPH and expressed as cpm were 354,208 (at 60min) and 135,800 (at 15min), respectively. During non-enzymatic lipid peroxidation a decrease of total chemiluminescence
(inhibition of lipid peroxidation) was observed when increasing concentrations of
melatonin were added to liver microsomes. The protective effect was concentration-dependent.
The inhibition observed in light emission was coincident with the protection of the
most PUFAs. Preincubation of microsomes with N-acetyl serotonin reduced these changes very dramatically. Thus, in the presence of
both antioxidants (0.36, 0.75, 1.5mM), light emission percent inhibition during non-enzymatic (ascorbate-Fe2+) lipid peroxidation of rat liver microsomes was for melatonin: 6.12, 16.20, 34.88
and for N-acetyl serotonin: 85.10, 88.48, 84.4 respectively. The incubation of rat liver microsomes
in the presence of NADPH (0.36, 0.75, 1.5 mM) produce a sudden increase of chemiluminescence
that gradually increased and reached a maximal value at about 15min; however, N-acetyl serotonin reduced these changes very efficiently.
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References
- Melatonin: a potent. Endogenous hydroxyl radical scavenger.Endocr. J. 1993; 1: 57-60
- Melatonin and structurally-related. endogenous indoles act as potent electron donors and radical scavengers in vitro.Redox. Rep. 1996; 2: 179-184
- Detection of melatonin and serotonin N-acetyltransferase and hydroxyindole-O-methyltransferase activities in rat ovary.Mol. Cell. Endocrinol. 1997; 136: 7-13
- Negative correlation of age and the levels of pineal melatonin, pineal N-acetyl serotonin, and serum melatonin in male rats.J. Exp. Zool. 1984; 229: 41-47
- Antioxidative and free radical scavenging activities of pineal indoles.J. Neural. Transm. 2000; 107: 1243-1251
- Mechanism of rat liver microsomal stearyl CoA desaturase. Studies of the substrate specificity, enzyme-substrate interactions, and the function of lipid.J. Biol. Chem. 1976; 251: 5095-5103
- An overview of lipid peroxidation with emphasis in outer segments of photoreceptors and the chemiluminescence assay.Int. J. Biochem. Cell. Biol. 2006; 38 (Review): 1482-1495
- N-acetylserotonin suppresses hepatic microsomal membrane rigidity associated with lipid peroxidation.Eur. J. Pharmacol. 2001; 428: 169-175
- The protection of long chain polyunsaturated fatty acids by melatonin during nonenzymatic lipid peroxidation of rat liver microsomes.J. Pineal Res. 2002; 32: 129-134
- Protective effect of melatonin on ascorbate-Fe2+ lipid peroxidation of polyunsaturated fatty acids in rat liver, kidney and brain microsomes: a chemiluminescence study.J. Pineal Res. 2005; 39: 164-169
- Isolation of rat liver microsomes by gel filtration.Anal. Biochem. 1973; 54: 597-603
- A simple method for the isolation and purification of total lipids from animal tissues.J. Biol. Chem. 1957; 226: 497-509
- Protein measurement with Folin phenol reagent.J. Biol. Chem. 1951; 193: 265-275
- The relationship between chemiluminescence and lipid peroxidation in rat hepatic microsomes.Arch. Biochem. Biophys. 1979; 192: 344-351
- Organization of multiple cytochrome P450s with NADPH-cytochrome P450 reductase in membranes.Pharmacol. Ther. 2003; 98: 221-233
- The mechanism of NADPH-dependent lipid peroxidation. The propagation of lipid peroxidation,.J. Biol. Chem. 1979; 254: 5892-5899
- Paradoxical influence of Ca++ on lipid peroxidation.Indian J. Exp. Biol. 1996; 34: 1071-1076
- Spectroscopic evidence for the generation of singlet oxygen in the reduced nicotinamide adenine dinucleotide phosphate-dependent microsomal lipid peroxidation system.J. Biol. Chem. 1975; 250: 2404-2406
- Protective effect of indoleamines on in vitro ascorbate-Fe2+ dependent lipid peroxidation of rod outer segment membranes of bovine retina.J. Pineal Res. 2003; 35: 276-282
- Further insights into the reaction of melatonin with hydroxyl radical.Bioorg Chem. 2002; 30: 371-382
- Reaction of melatonin and related indoles with hydroxyl radicals: EPR and spin trapping investigations.Free Radical Biol. Med. 1997; 23: 367-372
- Interactions between melatonin and nicotinamide nucleotide: NADH preservation in cells and in cell-free systems by melatonin.J. Pineal Res. 2005; 39: 185-194
- Distinction between enzymic and nonenzymic lipid peroxidation.J. Chromatogr. A. 1996; 743: 293-300
Article info
Publication history
Accepted:
June 17,
2007
Received:
April 11,
2007
Identification
Copyright
© 2007 Elsevier Ltd. Published by Elsevier Inc. All rights reserved.
