Abstract:

Melatonin, a naturally occuring chemical mediator, although assigned a diverse range of functions, has attracted interest because of its ability to function as a free radical scavenger. Its major hepatic metabolite and photoproduct, 6-hydroxymelatonin (6-OHM), also shares this property. Since singlet oxygen and quinolinic acid (QUIN) are critically involved in the pathology of neurotoxicity, the objective of this study was to investigate the ability of 6-OHM to scavenge singlet oxygen and evaluate its ability to scavenge superoxide anions and reduce QUIN-induced neurotoxicity in the hippocampus in-vivo. The results show that 6-OHM is an efficient inhibitor of singlet oxygen formation as indicated by the rate constants and quantum yields reported for 6-OHM and zinc phthalocyanine (ZnPc), respectively. 6-OHM, appears to reduce QUIN-induced superoxide anion generation in the hippocampus, which provides some evidence of the neuroprotective effects of 6-OHM.

Document Type: Research article

DOI: 10.1211/0022357056424

Affiliations: 1: Division of Pharmacology, Faculty of Pharmacy, Rhodes University, Grahamstown, 6140, South Africa 2: Department of Chemistry, Rhodes University, Grahamstown, 6140, South Africa 3: School of Pharmacy and Molecular Sciences, James Cook University, Townsville, QLD, 4811, Australia