In vitro activity: Hydralazine impairs up-regulation of RAG-2 gene expression and reduces secondary Ig gene rearrangements. Hydralazine subverts B lymphocyte tolerance to self and contributes to generation of pathogenic autoreactivity by disrupting receptor editing. Hydralazine directly scavenges free acrolein, decreasing intracellular acrolein availability and thereby suppressing macromolecular adduction. Hydralazine inhibits cross-linking if adding 30 min after commencing acrolein exposure but is ineffective if added after a 90-min delay. Hydralazine (0.1-10 mM) inhibits both extracellular and intracellular ROS production by inflammatory macrophages, by a ROS-scavenging mechanism probably affecting superoxide radical (O(2)(*-))-generation by xanthine oxidase (XO) and nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NADH/NADPH) oxidase. Hydralazine (0.1-10 mM) significantly reduces NO(*) generation, and this effect is attributable to an inhibition of NOS-2 gene expression and protein synthesis. Hydralazine also effectively blocks COX-2 gene expression which perfectly correlated with a reduction of protein levels and PGE(2) synthesis.

Proc Natl Acad Sci U S A. 2007 Apr 10;104(15):6317-22; J Pharmacol Exp Ther. 2004 Sep;310(3):1003-10.