Figure 2.

The physiological actions of PON enzymes in the defense against lipid oxidation. PON1 and PON3 proteins are produced in the liver and excreted into plasma where they are bound to HDL.The PON2 protein is found intracellularly in the liver, brain, kidneys, heart, pancreas, intestine and endothelial and smooth muscle cells. All three enzymes are able to potentiate macrophage cholesterol efflux and to prevent lipoprotein oxidation by hydrolyzing lipid peroxides and, due to lactonase activity, to neutralize the homocysteine (Hcy) thiolactone tissue toxicity [7,8,9,15,17].