Localization and interactions of melatonin in dry cholesterol/lecithin mixed reversed micelles used as cell membrane models

Abstract

The state of melatonin confined in dry cholesterol/lecithin mixed reversed micelles dispersed in CCl4 was investigated using 1H-NMR and FT-IR spectroscopies as a function of the melatonin to lecithin molar ratio (R(MLT)) and of the cholesterol to lecithin molar ratio (R(CHL)). An analysis of experimental results leads to the hypothesis that, independent of R(MLT) and as a consequence of anisotropic melatonin/lecithin, melatonin/cholesterol and cholesterol/lecithin interactions, melatonin is totally solubilized in reversed micelles. Melatonin is mainly located in and oriented in the nanodomain constituted by the hydrophilic groups of cholesterol and lecithin. A competition of melatonin and cholesterol for the hydrophilic binding sites of the reversed micelles was observed by changing the R(CHL). Some possible biological implications of the specific interactions governing the solubilization process, the preferential location and the peculiar properties of melatonin confined in cholesterol/lecithin mixed reversed micelles are discussed.

Synthesis of Rigid Cyclodextrin-Containing Polymeric Resins for Adsorption

“…Figure 1 shows the IR spectrum of a b-CD-containing resin synthesized using the method above. It has a large negative peak corresponding to the OH stretching at the 3391 cm )1 position that was reported by Bongiorno et al [23] for pure b-CD crystals. This indicates that the resin contains a large amount of OH groups contributed by b-CD.…”

Inclusion complexes of cyclomaltooligosaccharides (cyclodextrins) with melatonin in solid phase

“…Similar results have been also achieved by analysis of MLT containing anhydrous micellar systems. 33 These data can justify also the strong protection effect, almost against free radicals, of MLT on cell membranes, that have been reported. [4][5][6][7][8] Infrared spectra on the solid complex demonstrated that in the formation of inclusion complexes an important contribution is due to polar bonds formation-modification, thus evidencing once more 33 that MLT is preferentially localised in interfacial nano-districts, between polar and apolar domains.…”

Concentration-dependent effect of melatonin on DSPC membrane

“…These interactions can also alter the physicochemical properties and thus the functioning of the membranes. Melatonin is one of the most important molecule among the endogenous molecules that could change membrane properties, because it penetrates all physiologic barriers [11,38,39]. Moreover, melatonin and its metabolites have antioxidant properties that prevent damage induced by reactive species through several mechanisms, principally as a scavenger of these oxidative agents [40][41][42][43][44][45][46].…”