Redox state of dipyridamole is a critical determinant for its beneficial antioxidant and antiinflammatory effects.
Dipyridamole, a well-known inhibitor of cGMP-dependent phosphodiesterase and the adenosine transporter, reportedly possesses antioxidant properties and attenuates reactive oxygen species (ROS) formation in platelet and endothelial cells. The relevance of the redox status of this compound or the mechanism for its redox-dependent effects is unknown. Oxidation of dipyridamole by horseradish peroxidase and hydrogen peroxide diminished its fluorescence and attenuated dipyridamole-mediated DPPH and ferric ferrozine reduction. Oxidation also led to elimination of dipyridamole's redox-sensitive properties, including inhibiting Cu (II)-induced LDL oxidation and ROS generation. Attenuation of activation- induced platelet release of soluble CD40 ligand (sCD40L) was diminished after dipyridamole oxidation. Dipyridamole but not oxidized dipyridamole effectively inhibited platelet adhesion to collagen-coated slides under flow conditions. By Western blot analysis, dipyridamole enhanced stimulation-induced platelet VASP phosphorylation, whereas oxidized dipyridamole caused attenuation. Using luciferase assays and nuclear translocation studies with confocal microscopy and Western blot analysis, native dipyridamole diminished TNF alpha or thrombin-induced NF kappa B activation and I kappa B alpha phosphorylation. Oxidized dipyridamole had no effect on TNFalpha-mediated NF kappa B activation. These results indicate: (1) the redox state of dipyridamole regulates its antioxidant properties; (2) dipyridamole's platelet inhibitory effects are manifested by enhanced VASP phosphorylation and platelet adhesion on collagen; and (3) dipyridamole's antioxidant effects in vascular cells are at least partially mediated via suppression of inflammatory NF kappa B signaling.
Chakrabarti
Subrata
S
Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118, USA. subrata@bu.edu
Blair
Price
P
Wu
Cindy
C
Freedman
Jane E
JE
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000097:blood / Q000737:chemistry / Q000494:pharmacology*; D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000737:chemistry; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D023201:CD40 Ligand / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D004176:Dipyridamole / Q000097:blood / Q000737:chemistry / Q000494:pharmacology*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D005290:Ferric Compounds / Q000737:chemistry; D018922:HL-60 Cells; D006801:Humans; D006834:Hydrazines / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D020672:I-kappa B Proteins / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000737:chemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D008840:Microfilament Proteins / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D010084:Oxidation-Reduction; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010851:Picrates; D010973:Platelet Adhesiveness / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D051996:Transcription Factor RelA / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D000098662:Vasodilator-Stimulated Phosphoprotein
D000894:Anti-Inflammatory Agents, Non-Steroidal; D000975:Antioxidants; D001713:Biphenyl Compounds; D015815:Cell Adhesion Molecules; D005290:Ferric Compounds; D006834:Hydrazines; D020672:I-kappa B Proteins; D008077:Lipoproteins, LDL; D008840:Microfilament Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; D010750:Phosphoproteins; D010851:Picrates; D017382:Reactive Oxygen Species; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000098662:Vasodilator-Stimulated Phosphoprotein; D000072000:NF-KappaB Inhibitor alpha; D023201:CD40 Ligand; D004176:Dipyridamole; D006861:Hydrogen Peroxide; C004931:1,1-diphenyl-2-picrylhydrazyl