Emodin inhibited NADPH-quinone reductase competitively and induced cytotoxicity in rat primary hepatocytes

Consumption of Cassia occidentalis (CO) seeds, a ubiquitously distributed weed plant, is responsible for a pathological condition known as hepato-myo-encephalopathy (HME). The toxicity of CO seeds is largely attributed to the presence of anthraquinones (AQs). Here, we report that Emodin, a CO anthraquinone, inhibits the enzymatic activity of NADPH-Quinone reductase, which is an intracellular enzyme fundamentally involved in the detoxification of quinone containing compounds. Emodin binds to the active site of the enzyme and acts as a competitive inhibitor with respect to 2, 6-Dichlorophenolindophenol, a known substrate of NADPH-Quinone reductase. Moreover, our in-vitro study further revealed that Emodin was cytotoxic to primary rat hepatocytes.