Permeability of pure lipid bilayers to melatonin

Abstract

Melatonin, the chief hormone of the pineal gland, has been reported to interact with a variety of different cells. This ubiquitously acting hormone has been found to interact with protein receptors both at the cell membrane and in the nucleus. Moreover, melatonin was recently shown to be a very potent hydroxyl radical scavenger. The present work focuses on the interaction of melatonin with pure lipid bilayers. It is shown that melatonin can cross multilamellar lipid vesicles, which are used here as model systems for the lipid phase of biological membranes. Thus, the data prove that melatonin can easily pass through the cell membrane and bath every part of the cell, as previously suggested in the literature. Melatonin lipid association constant was calculated based on the change of the hormone fluorescence intensity due to its penetration into the hydrophobic lipid phase. Though melatonin was recently shown to be highly soluble in aqueous media, its lipid association constant is rather high, indicating that the biological action of the hormone is likely to be at the membrane level, either via its interaction with membrane receptors, and/or as a lipoperoxidation radical scavenger.

Strategies for Safe and Effective Therapeutic Measures for Chronic Arsenic and Lead Poisoning

“…In animal experiments, melatonin prevented the induction of free radical damage caused by a variety of conditions including ingestion of toxins, ionizing radiation, ischemia, reperfusion and excessive exercise 192,[195][196][197][198] . Melatonin has a molecular weight of 232 and is both lipid 199,200) and water soluble, although its solubility in lipid is clearly greater 201) . Therapeutic efficacy of melatonin either individually or in combination with succimer (DMSA) was recently studied by us in rats 187) .…”

Melatonin as potential candidate to prevent the toxicity induced by chemical warfare agents

“…crosses easily cell membranes, including blood brain barrier (Costa et al 1995), reaching all subcellular compartments and allowing it to be administered either orally or intravenously. Taking into account melatonin's low toxicity and that patients treated with high doses of melatonin do not experience any harmful side effects (Seabra et al 2000), its potential spectrum for improving medical treatment against CWAs seems to be wide.…”

Melatonin Inhibits Iron‐Induced Epileptic Discharges in Rats by Suppressing Peroxidation

“…Injection of iron ions into the rat cortex causes acute epileptiform discharges in the EEG (3)(4)(5). Histopathologic assessment of the site of isocortical injection of iron ions shows focal edema formation within 24 h, followed by necrosis, neuronal loss, and gliosis during a 30-day period (7).…”