Effects of glutathione, α-tocopherol, ascorbic acid and pH On the synthesis of methylguanidine

Abstract

Methylguanidine is possibly to be an oxidative product of creatinine. In this study, we investigated the effects of some reagents which were related to oxidation in some different pH conditions. Nonbiological synthesis of methylguanidine from creatinine (100 mg dl) in Tris-HC1 buffer was stimulated in acidic pH. Glutathione (final concentration 2 mg/ml) inhibited the synthesis of methylguanidine completely in the pH range from 6.6 to 8.2 within 12 hours, α-tocopherol (1 mg/ml) also inhibited the synthesis of methylguanidine in acidic pH. Ascorbic acid (1 mg/ml) stimulated the synthesis of methylguanidine in the pH range from 6.6 to 8. 2, and the stimulatory effect became stronger in basic pH. Stimulation and inhibition of methylguanidine synthesis by these reagents were also observed in the biosynthesis of methylguanidine in isolated rat hepatocytes. These results suggested that some substances such as glutathione, α-tocopherol and ascorbic acid might affect the methylguanidine synthesis in vivo.