Aged garlic extract inhibits peroxynitrite-induced hemolysis

Nitric oxide (NO), which is synthesized by constitutive NO synthase (cNOS), plays important roles in physiological functions of the cardiovascular system. However, NO, which is synthesized by inducible NOS, is detrimental when it reacts with superoxide to form peroxynitrite. Peroxynitrite is recognized as a powerful oxidant, and results in vascular or tissue damage. We have previously reported that aged garlic extract (AGE) enhances NO production through cNOS stimulation. In the present study, we determined the effect of AGE, its fractions or constituents on peroxynitrite-induced hemolysis using rat erythrocytes. Incubation of rat erythrocytes with peroxynitrite (300 microM) for 30 min at 37 degrees C caused 4-fold hemolysis. AGE (0.14-0.57 %w/v) added to an erythrocyte suspension was found to reduce peroxynitrite-induced hemolysis in a concentration-dependent manner. Of the AGE fractions, a polar fraction and a low-molecular-weight fraction both suppressed the hemolysis to the same degree as that seen with AGE. S-allylcysteine, one of the major compounds in AGE, also reduced hemolysis at 1-10 mM dose-dependently. These data indicate that AGE and its compounds protect erythrocytes from membrane damage induced by peroxynitrite, suggesting that AGE could be useful for prevention of cardiovascular diseases associated with oxidative stress or dysfunction of NO production.