The interaction methylene blue and glutathione-S-transferase purified from human erythrocytes

Abstract

It is known that textile dyes have various risks on human health. Glutathione-S-transferase enzymes play a critical role in the detoxification of xenobiotics in living systems. This study aimed to examine the interaction of methylene blue with human erythrocyte glutathione-S-transferase purified in one step. Human erythrocyte glutathione-S-transferase was purified with approximately 750-fold purification and 30% efficiency by glutathione agarose affinity chromatography. The results showed that the enzyme was inhibited by methylene blue with an IC50 value of 1.40 mmol/L. The Ki constant of methylene blue was 1.17 mmol/L. The Lineweaver–Burk graph of the methylene blue showed that the type of inhibition was compatible with mixed type inhibition. A new third spot was also detected by thin-layer chromatography. Furthermore, the cytotoxicity of methylene blue on human erythrocytes was evaluated and it was found that the haemolysis per cent of methylene blue on erythrocytes was approximately 14%.