Diminution of biological reactivity of ethanol by changing the solution structure by weak ultrasonication

The weak ultrasonication (40 kHz, 12 mW, 1 week) of ethanol solutions was found to reduce stimulation of the senses of smell and taste by the ethanol on the basis of blind tests with an aqueous ethanol solution (33.0% w/v) and an immature distilled spirit (25.0% v/v). Experiments on mice also demonstrated that a treated aqueous ethanol solution had a weaker depressant effect on the central nervous system, as evaluated by the relative frequency with which mice regained the righting reflex at a dose of either 4.0 or 4.5 g/kg (p < 0.05 or p < 0.01, respectively) and by the reduction in rectal temperature at a dose of 5.0 g/kg (p < 0.05) soon after ethanol administration. Analyses of both the ethanol concentration by head-space gas chromatography and the free radicals by electron spin resonance spectrometer failed to reveal any chemical changes in aqueous ethanol solutions subjected to weak ultrasonication. However, measurement of the spin-lattice relaxation time (T1) of the 2H of water molecules by 2H-NMR showed that the treatment slightly accelerated the thermal motion of water molecules in the solutions. Treated solutions were also found to have a slightly higher density than untreated ones. These physical data demonstrate that weak ultrasonication induces a structural change, such as a more compact and homogeneous structure by changing the microdynamic behavior of the solution. These biological and physical studies suggest that only a slight structural change in an ethanol solution induces a marked change in the biological reactivity of ethanol without any chemical modification of the solution itself.