Microwaves (2.45 GHz) are shown to accelerate the initial rate of lipid peroxidation in posphatidylcholine liposomes for exposures within Specific Absorption Rate (SAR) range of 3.5 to 8 mW/g. This response was not observed for SAR below 3.5 mW/g. The peroxidation of microwave and sham-exposed liposomes was initiated by Cu2+/H2O2 and the conjugated dienes (CD) formation was followed. Unusually, vitamin E, at 0.01 mM concentration, and melatonin, at 0.01 mM and 0.08 mM concentrations, did not inhibit the rate of CD formation in liposomes, and the microwave-induced effects are observed. However, vitamin E, at 0.05 mM concentration, or melatonin, at 1 mM concentration, protected liposomes from Cu2+/H2O2-induced peroxidation. Consequently, no microwave-induced effects were observed. We examined the role of hydroxyl radical (cntdotOH) species, possibly generated in the reaction of Cu2+ with H2O2, for microwave-induced effects. Accordingly, the hydroxyl radical scavenger mannitol inhibited the microwave-induced effects. When the peroxidation of sham and microwave-exposed liposomes was initiated by 2,2'-azobis(2-amidinopropane) dihydrochhloride (AAPH), no enhancement in the rate of CD formation was observed. These studies demonstrate that microwaves at 2.45 GHz only affect the initial rate of lipid peroxidation initiated by Cu2+/H2O2 and also that hydroxyl radicals could modulate this response.
The enhancement of lipid peroxidation kinetics in phosphatidylcholine liposomes by microwave radiation
Ramundo Orlando Alfonsina;
1999
Abstract
Microwaves (2.45 GHz) are shown to accelerate the initial rate of lipid peroxidation in posphatidylcholine liposomes for exposures within Specific Absorption Rate (SAR) range of 3.5 to 8 mW/g. This response was not observed for SAR below 3.5 mW/g. The peroxidation of microwave and sham-exposed liposomes was initiated by Cu2+/H2O2 and the conjugated dienes (CD) formation was followed. Unusually, vitamin E, at 0.01 mM concentration, and melatonin, at 0.01 mM and 0.08 mM concentrations, did not inhibit the rate of CD formation in liposomes, and the microwave-induced effects are observed. However, vitamin E, at 0.05 mM concentration, or melatonin, at 1 mM concentration, protected liposomes from Cu2+/H2O2-induced peroxidation. Consequently, no microwave-induced effects were observed. We examined the role of hydroxyl radical (cntdotOH) species, possibly generated in the reaction of Cu2+ with H2O2, for microwave-induced effects. Accordingly, the hydroxyl radical scavenger mannitol inhibited the microwave-induced effects. When the peroxidation of sham and microwave-exposed liposomes was initiated by 2,2'-azobis(2-amidinopropane) dihydrochhloride (AAPH), no enhancement in the rate of CD formation was observed. These studies demonstrate that microwaves at 2.45 GHz only affect the initial rate of lipid peroxidation initiated by Cu2+/H2O2 and also that hydroxyl radicals could modulate this response.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
