Interactions of melatonin with membrane models: Portioning of melatonin in AOT and lecithin reversed micelles

Abstract

The interaction of melatonin with water containing either sodium bis (2-ethylhexyl) sulfosuccinate (AOT) or soybean phosphatidylcholine (lecithin) reversed micelles has been investigated by UV absorption spectroscopy, at a molar ratio of melatonin:surfactant 1:800 for AOT and 1:400 for lecithin reversed micelles, and by varying the water:surfactant molar ratio (R). Our results suggest that in the presence of domains from apolar organic solvent to surfactant and to water, melatonin positions itself in the micellar phase, with a preferential location in the surfactant polar head group domain, independent of the nature of the surfactant and the amount of water encapsulated into the micellar core. Effects are due to the hydrophilic and lipophilic moieties of melatonin. The effectiveness of melatonin as an electron donor and free radical scavenger has been recently recognized. While supporting the hypothesis that melatonin may provide antioxidant protection without the benefit of receptors, present findings may suggest that the molecule could easily scavenge aqueous as well as lipophilic radicals.

Involvement of melatonin applied to Vigna radiata L. seeds in plant response to chilling stress

“…In another study, shrinkage and disruption of plasma membrane caused by chilling were almost completely inhibited by MEL treatment in the suspension of carrot cells, suggesting that MEL is also involved in the integrity of membranes [9]. This indolamine might position itself between the polar heads of polyunsaturated fatty acids within the cell membranes, thus reducing lipid peroxidation and maintaining their optimal fluidity [42,43]. A positive dose-dependent impact of MEL on the membrane integrity, lipid peroxidation products and electrolyte leakage in water-stressed cucumber seedlings have been previously demonstrated [28].…”

H-NMR and FT-IR study of the state of melatonin confined in membrane models: location and interactions of melatonin in water free lecithin and AOT reversed micelles

“…Some investigation on the localization of MLT in systems characterized by the presence of aqueous, apolar and polar micro domains, as inversed micelles including water in the micellar core, 18 phospholipidic layers 19 and cyclodextrins 20 in aqueous medium have been reported. The results indicate that MLT locates in the interface between the polar head region and the water enclosed in the micellar core, 18 between the two layers in phospholipide bi-layers 19 and it is inserted into the hydrophobic cavities of cyclodextrins. 20 On the other hand, nervous cells of the brain cannot be regenerated and those hit from free radicals are irremediably destroyed.…”

Actions of Melatonin in the Reduction of Oxidative Stress

“…When melatonin is taken into cellular membranes, it mainly localizes in a superficial position in lipid bilayers near the polar heads of membrane phospholipids [17]. While in this position it obviously is capable of functioning as a free radical scavenger and it may also provide an indirect means by which the membranes can resist oxidative damage.…”