Application of Riboflavin-Deficient Rat Erythrocytes in the in Vitro Assay of Faba Bean Toxicity

Background: Faba bean toxicity (favism) is a common condition observed in our region. Objective: To develop a short and simple technique involving the use of riboflavin-deficient rats to test in vivo faba bean toxicity. Methods/Results: Sprague Dawley rats were maintained on a riboflavin-deficient diet and their vitamin B2 status was monitored by the assay of erythrocyte glutathione reductase (EGR).  Their blood was found to be sensitive enough as early as 5 weeks of eating the deficient diet.  Initially RBC preparations from the riboflavin-deficient rats were used to test the toxicity of different concentrations of divicine (0.0-13.5 mM).  It was found that an increase in divicine concentration resulted in an appreciable drop in reduced glutathione (GSH) of RBC.  The assay procedure was then used to test the effectiveness of certain detoxification treatments of faba beans. A high correlation (r= 0.9) was noted between residual vicine (the main favism factor) concentration and the toxicity index (TI) of treated samples indicating the suitability of the above procedure for toxicity assay. Conclusion: It is recommended to use blood from Sprague Dawley rats that have been fed a riboflavin-deficient diet for about 5 weeks or longer, in the bioassay of toxicity of faba beans and their isolated favism principles