Iodinated radiographic contrast media possess antioxidant properties in vitro

To study potential properties of iodinated radiographic contrast media (IRCM) for intravascular use in in vitro free radical generating reactions.

Superoxide (*O2-) and hydroxyl (*OH) radicals were generated in xanthine oxidase and Fenton reactions. *O2- was assayed by the nitroblue tetrazolium (NBT) method, whereas *OH was assayed by an aromatic hydroxylation (2-hydroxybenzoic acid) method. Total antioxidant status (TAS) of test substances was determined by a colorimetric assay. Finally, acetyl-cholinesterase (AChE) activity was measured in the absence and presence of IRCM.

High concentrations (>50 mM) of IRCM inhibited *O2- production, ionic more than non-ionic IRCM. Medium concentrations (25-50 mM) of IRCM reduced *OH production, and both types of IRCM were equally potent. Low concentrations (<25 mM) of non-ionic IRCM displayed higher antioxidant capacity than their ionic counterparts when tested in the TAS assay. Visipaque 320 (iodixanol) was found to have the highest TAS value, followed by Omnipaque 350 (iohexol), Hexabrix 320 (ioxaglate), and Urografin 370 (diatrizoate).

IRCM have in vitro antioxidant properties in concentrations relevant for their clinical application. These properties may therefore be of potential importance when evaluating IRCM effects in vivo, particularly those concerning cardiovascular and renal function.