Effects of some drugs on human erythrocyte 6-phosphogluconate dehydrogenase: An in vitro study

Abstract

The inhibitory effects of some drugs on 6-phosphogluconate dehydrogenase from human erythrocytes have been investigated. For this purpose, initially, erythrocyte 6-phosphogluconate dehydrogenase was purified 3364 times in a yield of 58% by using ammonium sulfate precipitation and 2′,5′-ADP Sepharose 4B affinity gel. A temperature of 4°C was maintained during the purification process. Enzyme activity was determined with the Beutler method by using a spectrophotometer at 340nm. This method was utilized for all kinetic studies. Many commonly used drugs were investigated in this study. Some drugs (ketotifen (Ki: 8.3±1.7 μM), dacarbazine (Ki: 10.1±0.7 μM), meloxicam (Ki: 50.9±13.2 μM), furosemide (Ki: 127±37.8 μM), methotrexate (Ki: 136.7±25.3 μM), metochloropramide hydrochloride (Ki: 2.1113±0.6979mM), ritodrine hydrochloride (Ki: 6.0353±1.2783mM), and gadopentetic acid (Ki: 73.4±21.9mM)) inhibited enzyme activity in vitro. Ki constants for the enzyme were found by means of LineweaverBurk graphs. All drugs showed non-competitive inhibition. In addition, IC50 values of the drugs were determined by plotting activity percent vs [I]. © 2010 Informa UK Ltd.