Hydroxyl radical generation in beta-thalassemic red blood cells.
To provide more experimental evidence for the proposed role of oxygen free radicals in red blood cell (RBC) damage in beta-thalassemia, hydroxyl radical generation was studied in thalassemic (Th) vs. normal (N) RBC. .OH fluxes were quantified by the conversion of salicylic acid (SA) into its hydroxylated products, 2,3- and 2,5-dihydroxybenzoic acids (DHBA) and catechol, assayed with HPLC coupled to electrochemical detection. No significant difference in spontaneous .OH generation between N-RBC and Th-RBC was found. Ascorbic acid (0.5-3.0 mM) induced many-fold increases in SA hydroxylation in a dose-dependent manner in both types of cells. In the presence of ascorbate (1.0 mM), the SA hydroxylated products were determined in Th-RBC vs. N-RBC as follows (nmol/ml): 2,5-DHBA, 1.45 +/- 0.06 vs. 1.81 +/- 0.05 (p = 0.001); 2,3-DHBA, 1.89 +/- 0.21 vs. 1.15 +/- 0.08 (p = 0.008) and catechol, 0.87 +/- 0.13 vs. 0.38 +/- 0.05 (p = 0.006). The results showed significant increase in the total SA hydroxylation in Th-RBC as compared to N-RBC with a tendency to form 2,3-DHBA and catechol at the expanse of 2,5-DHBA. The excessive .OH generation in Th-RBC is attributed to the abnormally high content of redox active iron in the cytosolic and/or membrane compartments of these cells.
Grinberg
L N
LN
Department of Hematology, Hadassah University Hospital, Jerusalem, Israel.
Rachmilewitz
E A
EA
Kitrossky
N
N
Chevion
M
M
D002396:Catechols / Q000097:blood; D004912:Erythrocytes / Q000378:metabolism*; D005841:Gentisates; D006801:Humans; D062385:Hydroxybenzoates / Q000097:blood; D017665:Hydroxyl Radical / Q000097:blood*; D066298:In Vitro Techniques; D007501:Iron / Q000097:blood; D010084:Oxidation-Reduction; D012459:Salicylates / Q000097:blood; D020156:Salicylic Acid; D017086:beta-Thalassemia / Q000097:blood*
D002396:Catechols; D005841:Gentisates; D062385:Hydroxybenzoates; D012459:Salicylates; D017665:Hydroxyl Radical; C009135:2,3-dihydroxybenzoic acid; D007501:Iron; C034221:catechol; D020156:Salicylic Acid; C010925:2,5-dihydroxybenzoic acid