Gossypol-induced suicidal erythrocyte death

Side effects of gossypol, a polyphenolic component of Gossypium, with male contraceptive, anticancer, antimicrobial and antiviral activities include anemia due to accelerated demise of erythrocytes. Erythrocytes may be cleared from circulating blood following apoptosis-like suicidal death or eryptosis. Hallmarks of eryptosis are cell shrinkage and cell membrane scrambling with subsequent phosphatidylserine-exposure at the cell surface. Stimulators of eryptosis include increase of cytosolic Ca(2+)-activity ([Ca(2+)](i)). The present study explored, whether gossypol stimulates eryptosis of human erythrocytes. Utilizing flow cytometry, [Ca(2+)](i) was estimated from Fluo-3 fluorescence, cell volume from forward scatter, phosphatidylserine-exposure from annexin-V-binding, and hemolysis from hemoglobin release. A 48 h exposure to gossypol (0.75 μM) significantly increased [Ca(2+)](i), decreased forward scatter and increased annexin-V-binding. Gossypol exposure was followed by a slight but significant increase of hemolysis. Removal of extracellular Ca(2+) significantly blunted the effect of gossypol (1 μM) on annexin-V-binding. The present observations reveal a novel effect of gossypol on human erythrocytes, which contributes to or even accounts for the triggering of anemia by this substance.