Protective Activity of the Extracts from Japanese eel (Anguilla japonica) Against Zinc-induced Neuronal Cell Death: Carnosine and an Unknown Substance

Abstract

The Japanese eel, Anguilla japonica, is the traditional staple food in summer in Japan. We have previously reported that both carnosine and an aqueous extract from eel muscle prevent zinc-induced GT1-7 cell death, which is associated with neuronal death after transient global ischemia. In this study, we found that these protective activities were exhibited by the heat-treated extracts from both eel muscle and skin. We developed a high-performance liquid chromatography system for quantifying carnosine; this system demonstrated that the muscle extract contained carnosine in an amount sufficient for preventing zinc-induced GT1-7 cell death, which reveals that carnosine is the substance in the muscle extract that is responsible for the protective activity. The analysis of the expression of zinc- inducible gene indicates that carnosine acts as an intracellular protective substance in GT1-7 cells. We also demonstrated that the eel skin contained unknown substance(s) that prevent zinc-induced cell death.