Stimulation of Hemolysis and Eryptosis by α-Mangostin through Rac1 GTPase and Oxidative Injury in Human Red Blood Cells

Background: Chemotherapy-related anemia is prevalent in up to 75% of patients, which may arise due to hemolysis and eryptosis. Alpha-mangostin (alpha-MG) is a polyphenolic xanthonoid found in the mangosteen tree (Garcinia mangostana) whose antitumor medicinal properties are well-established. Nevertheless, the potential toxic effects of alpha-MG on red blood cells (RBCs) have, as of yet, not been as well studied. Methods: RBCs were exposed to 1-40 mu M of alpha-MG for 24 h at 37 degrees C. Hemolysis and related markers were measured using colorimetric assays, eryptotic cells were identified through Annexin-V-FITC, Ca2+ was detected with Fluo4/AM, and oxidative stress was assessed through H2DCFDA using flow cytometry. The toxicity of alpha-MG was also examined in the presence of specific signal transduction inhibitors and in whole blood. Results: alpha-MG at 10-40 mu M caused dose-dependent hemolysis with concurrent significant elevation in K+, Mg2+, and LDH leakage, but at 2.5 mu M it significantly increased the osmotic resistance of cells. A significant increase was also noted in Annexin-V-binding cells, along with intracellular Ca2+, oxidative stress, and cell shrinkage. Moreover, acetylcholinesterase activity was significantly inhibited by alpha-MG, whose hemolytic potential was significantly ameliorated by the presence of BAPTA-AM, vitamin C, NSC23766, and isosmotic sucrose but not urea. In whole blood, alpha-MG significantly depleted intracellular hemoglobin stores and was selectively toxic to platelets and monocytes. Conclusions: alpha-MG possesses hemolytic and eryptotic activities mediated through Ca2+ signaling, Rac1 GTPase activity, and oxidative injury. Also, alpha-MG leads to accelerated cellular aging and specifically targets platelet and monocyte populations in a whole blood milieu.