In vitro effects of some drugs on human erythrocyte glutathione reductase

Aim: The effects of dacarbazine, thiocolchicoside, methotrexate, olanzapine, pantoprazole sodium, and 5-fluorouracil on the enzyme activity of glutathione reductase (GR) were studied using human erythrocyte GR enzymes in in vitro studies, respectively. Materials and methods: The enzyme was purified 3333-fold from human erythrocytes in a yield of 44.44% with 4.0 U/mg. The purification procedure involved the preparation of hemolysate, ammonium sulfate precipitation, 2', 5'-ADP Sepharose 4B affinity chromatography, and Sephadex G-200 gel filtration chromatography. SDS-PAGE showed a single band for enzyme. Purified enzyme was used in the in vitro studies. Results: In the in vitro studies, IC50 values and Ki constants were 0.014 mM and 0.0121 +/- 0.0026 mM for dacarbazine, and 0.054 mM and 0.0135 +/- 0.0024 mM for thiocolchicoside, 0.31 mM and 0.1213 +/- 0.040 mM for methotrexate, 0.35 mM and 0.3173 +/- 0.0981 mM for olanzapine, 0.94 mM and 0.5413 +/- 0.0728 mM for pantoprazole sodium, and 98.57 mM and 69.611 +/- 9.690 mM for 5-fluorouracil, showing the inhibition effects on the purified enzyme. Inhibition types were non-competitive for dacarbazine, methotrexate, olanzapine, and 5-fluorouracil and competitive for thiocolchicoside and pantoprazole sodium. Conclusion: All the drugs indicated the inhibitory effects on the enzyme.