Favism: Effect of divicine on rat erythrocyte sulfhydryl status, hexose monophosphate shunt activity, morphology, and membrane skeletal proteins

Favism is an acute anemic crisis that can occur in susceptible individuals who ingest fava beans. The fava. bean pyrimidine aglycone divicine has been identified as a hemotoxic constituent; however, its mechanism of toxicity remains unknown. We have shown recently that divicine can induce a favic-li ke response in rats and that divicine is directly toxic to rat red cells. I n the present study, we have examined the effect of hemotoxic concentration s of divicine on rat erythrocyte sulfhydryl status, hexose monophosphate (H MP) shunt activity, morphology, and membrane skeletal proteins. rn vitro ex posure of rat red cells to divicine markedly stimulated HMP shunt activity and resulted in depletion of reduced glutathione with concomitant formation of glutathione-protein mixed-disulfides. Examination of divicine-treated r ed cells by scanning electron microscopy revealed transformation of the cel ls to an extreme echinocytic morphology. SDS-PAGE and immunoblotting analys is of the membrane skeletal proteins indicated that hemotoxicity was associ ated with the apparent loss of skeletal protein bands 2.1, 3, and 4.2, and the appearance of membrane-bound hemoglobin. Treatment of divicine-damaged red cells with dithiothreitol reversed the protein changes, which indicated that the observed alterations were due primarily to the formation of disul fide-linked hemoglobin-skeletal protein adducts. The data suggest that oxid ative modification of hemoglobin and membrane skeletal proteins by divicine may be key events in the mechanism underlying favism.