Protection of low density lipoprotein oxidation at chemical and cellular level by the antioxidant drug dipyridamole

Abstract

1 The oxidative modification of low density lipoprotein (LDL) is thought to be an important factor in the initiation and development of atherosclerosis. Natural and synthetic antioxidants have been shown to protect LDL from oxidation and to inhibit atherosclerosis development in animals. Synthetic antioxidants are currently being tested, by they are not necessarily safe for human use. 2 We have previously reported that dipyridamole, currently used in clinical practice, is a potent scavenger of free radicals. Thus, we tested whether dipyridamole could affect LDL oxidation at chemical and cellular level. 3 Chemically induced LDL oxidation was made by Cu(II), Cu(II) plus hydrogen peroxide or peroxyl radicals generated by thermolysis of 2,2'-azo-bis(2-amidino propane). Dipyridamole, (1-10 gM), inhibited LDL oxidation as monitored by diene formation, evolution of hydroperoxides and thiobarbituric acid reactive substances, apoprotein modification and by the fluorescence of cis-parinaric acid. 4 The physiological relevance of the antioxidant activity was validated by experiments at the cellular level where dipyridamole inhibited endothelial cell-mediated LDL oxidation, their degradation by monocytes, and cytotoxicity. 5 In comparison with ascorbic acid, a-tocopherol and probucol, dipyridamole was the more efficient antioxidant with the following order of activity: dipyridamole > probucol > ascorbic acid> a-tocopherol. The present study shows that dipyridamole inhibits oxidation of LDL at pharmacologically relevant concentrations. The inhibition of LDL oxidation is unequivocally confirmed by use of three different methods of chemical oxidation, by several methods of oxidation monitoring, and the pharmacological relevance is demonstrated by the superiority of dipyridamole over the naturally occurring antioxidants, ascorbic acid and a-tocopherol and the synthetic antioxidant probucol.

Dipyridamole inhibits sickling-induced cation fluxes in sickle red blood cells

“…28 To that list of diverse effects on membrane processes, we now add blockade of the increased membrane permeability to Na ϩ , K ϩ , and Ca ϩϩ induced by sickling. Morphological sickling was not altered by the drug, so the inhibitory effect of dipyridamole does not result from interference with polymerization of deoxygenated HbS.…”

Multifunctional Actions of Approved and Candidate Stroke Drugs

“…34 Dipyridamole inhibits oxidation of low density lipoprotein (LDL) and may prevent the development of atherosclerosis. 35 In various neuronal cell culture models dipyridamole was cytoprotective. 36,37 Dipyridamole also exerted neuroprotective properties in an embolic stroke model.…”

Translational Therapeutics of Dipyridamole

“…22 Compared with ascorbic acid, ␣-tocopherol, and probucol, DP was more efficient in inhibiting chemically or cellularly induced lowdensity lipoprotein (LDL) oxidation as monitored by diene formation, evolution of hydroperoxides and thiobarbituric acid reactive substances, apoprotein modification, and by the fluorescence of cis-parinaric acid. 23 The antioxidative effects of DP could also occur at the cellular level. At clinically relevant concentrations, DP protects erythrocyte membranes from oxidation and spares the antioxidant power of erythrocytes.…”