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 Ca2+-activity ([Ca2+]i). The present study explored, whether gossypol stimulates eryptosis of human erythrocytes. Utilizing flow cytometry, [Ca2+]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 [Ca2+]i, decreased forward scatter and increased annexin-V-binding. Gossypol exposure was followed by a slight but significant increase of hemolysis. Removal of extracellular Ca2+ 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.

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► The male contraceptive gossypol increases cytosolic Ca2+-activity in erythrocytes.
► Gossypol decreases erythrocyte cell volume.
► Gossypol triggers slight hemolysis.
► Gossypol stimulates erythrocyte membrane scrambling with phosphatidylserine exposure.
► The effect on cell membrane scrambling is blunted by removal of extracellular Ca2+.