N alpha-(1-deoxy-D-fructos-1-yl)-L-arginine, an antioxidant compound identified in aged garlic extract

Aged garlic extract (AGE) has been shown to have antioxidant activity. The organosulfur compounds, S-allyl-L-cysteine and S-allylmercapto-L-cysteine, are responsible, at least in part, for the antioxidant activity of AGE. To identify major active components, we fractionated AGE, using hydrogen perox ide scavenging activity as an antioxidative index. Strong activity in the a mino acid fraction was found and the major active compound was identified a s N alpha-(1-deoxy-D-fructos-1-yl)-L-arginine (Fru-Arg). Antioxidant activi ty of Fru-Arg was comparable to that of ascorbic acid, scavenging hydrogen peroxide completely at 50 mu mol/L and 37% at 10 mu mol/L. Quantitative ana lysis using the established HPLC system revealed that AGE contained 2.1-2.4 mmol/L of Fru-Arg, but none was detected in either raw or heated garlic ju ice. Furthermore, it was shown that a minimum of 4 mo aging incubation was required for Fru-Arg to be generated. These findings indicate that the agin g process is critical for the production of the antioxidant compound, Fru-A rg. These results may explain some of the variation in benefits among diffe rent commercially available garlic preparations.