PT  - JOURNAL ARTICLE
AU  - I. Tong Mak
AU  - William B. Weglicki
TI  - Potent Antioxidant Properties of 4-Hydroxyl-propranolol
AID  - 10.1124/jpet.103.058032
DP  - 2004 Jan 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 85--90
VI  - 308
IP  - 1
4099  - http://jpet.aspetjournals.org/content/308/1/85.short
4100  - http://jpet.aspetjournals.org/content/308/1/85.full
SO  - J Pharmacol Exp Ther2004 Jan 01; 308
AB  - The antioxidant properties of 4-HO-propranolol (4HOP), a major metabolite of propranolol, were studied and compared with that of propranolol and vitamin E (Trolox). When isolated hepatic microsomal membranes were peroxidized by an iron-catalyzed ·OH-generating system [dihydroxyfumarate +Fe (III)], 4HOP potently and concentration-dependently inhibited lipid peroxidation; the IC50 value was 1.1 μM, whereas those for Trolox and propranolol were 4.3 and 168 μM, respectively. When isolated human low-density lipoprotein (LDL) was oxidized by 7.5 μM Cu(II) for 9 h, 4HOP at 3 μM delayed the lag phase significantly by 108 min, which was comparable with that of probucol (98-min delay) but was far greater than that provided by propranolol (6 min) or Trolox (47 min). At 1 μM 4HOP, the delay was 45 min. When confluent cultured bovine aortic endothelial cells were exposed to the Fe-catalyzed oxy-radical system, acute loss of glutathione occurred (55% decrease in 50 min). Pretreatment of the cells with 0.067 to 6.7 μM 4HOP for 30 min provided increasing degrees of protection against the glutathione loss; the EC50 value was 1.2 μM, whereas those for Trolox and propranolol were 7.9 and 49 μM, respectively. The loss of cell survival due to the radical stress was also effectively preserved by 4HOP. In separate experiments, when the endothelial glutathione was oxidatively depleted by a peroxynitrite-generating system (3-morpholinosydnonimine), 4HOP also provided potent protective activities. In conclusion, 4HOP is 4- to 8-fold more potent than vitamin E and >100-fold more active than propranolol as a “chain-breaking” antiperoxidatant against membrane and LDL oxidation and can provide superior endothelial cytoprotective efficacy against oxygen- or nitrogen-derived oxidant-mediated cell injury. Being a major metabolite in human and with its plasma level approaching that of propranolol, 4-HO-propranolol may contribute, in part, to the cardiovascular therapeutic benefits of propranolol. The American Society for Pharmacology and Experimental Therapeutics