title: Apigenin-induced suicidal erythrocyte death.
abstract: Apigenin, a flavone in fruits and vegetables, stimulates apoptosis and thus counteracts cancerogenesis. Erythrocytes may similarly undergo suicidal cell death or eryptosis, characterized by cell shrinkage and phosphatidylserine exposure at the cell surface. Triggers of eryptosis include increase of cytosolic Ca(2+) activity ([Ca(2+)](i)), ceramide formation and ATP depletion. The present study explored the effect of apigenin on eryptosis. [Ca(2+)](i) was estimated from Fluo3-fluorescence, cell volume from forward scatter, phosphatidylserine exposure from annexin V binding, hemolysis from hemoglobin release, ceramide utilizing antibodies, and cytosolic ATP with luciferin-luciferase. A 48 h exposure to apigenin significantly increased [Ca(2+)](i) (≥ 1 μM), increased ceramide formation (15 μM), decreased ATP concentration (15 μM), decreased forward scatter (≥ 1 μM), and increased annexin V binding (≥ 5 μM) but did not significantly modify hemolysis. The effect of 15 μM apigenin on annexin V binding was blunted by Ca(2+) removal. The present observations reveal novel effects of apigenin, i.e. stimulation of Ca(2+) entry, ceramide formation and ATP depletion in erythrocytes with subsequent triggering of suicidal erythrocyte death, paralleled by cell shrinkage and phosphatidylserine exposure.
authors: Department of Physiology, University of Tuebingen, Gmelinstraße 5, 72076 Tuebingen, Germany.
authors: Mohanad
authors: M
authors: Zbidah
authors: Adrian
authors: A
authors: Lupescu
authors: Kashif
authors: K
authors: Jilani
authors: Abul
authors: A
authors: Fajol
authors: Diana
authors: D
authors: Michael
authors: Syed M
authors: SM
authors: Qadri
authors: Florian
authors: F
authors: Lang
mesh_terms: D047310:Apigenin / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D004912:Erythrocytes / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D006461:Hemolysis / Q000187:drug effects*
chemical_list: D047310:Apigenin; D002118:Calcium