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

The interaction of melatonin with water containing either sodium bis (2-eth ylhexyl) sulfosuccinate (AOT) or soybean phosphatidylcholine (lecithin) rev ersed micelles has been investigated by UV absorption spectroscopy. at a mo lar ratio of melatonin:surfactant 1:800 for AOT and 1:400 for lecithin reve rsed micelles, and by varying the water:surfactant molar ratio (R). Our res ults suggest that in the presence of domains from apolar organic solvent to surfactant and to water. melatonin positions itself in the micellar phase. with 1 a preferential location in the surfactant polar head group domain. independent of the nature of the surfactant and the amount of water encapsu lated into the micellar core. Effects are due to the hydrophilic and lipoph ilic moieties of melatonin. The effectiveness of melatonin as an electron d onor and free radical scavenger has been recently recognized. While support ing the hypothesis that melatonin may provide antioxidant protection withou t the benefit of receptors. present findings may suggest that the molecule could easily scavenge aqueous as well as lipophilic radicals.