Peroxynitrite flux-mediated LDL oxidation is inhibited by manganese porphyrins in the presence of uric acid.

Published

Journal Article

We have studied the role of three Mn(III)porphyrins differing in charge, alkyl substituent length and reactivity, on LDL exposed to low fluxes of peroxynitrite (PN) in the presence of uric acid. Mn(III)porphyrins (5 microM, MnTE-2-PyP(5+), MnTnOct-2-PyP(5+), and MnTCPP(3-)) plus uric acid (300 microM) inhibited cholesteryl ester hydroperoxide formation, changes in REM as well as spared alpha- and gamma-tocopherol. MnTnOct-2-PyP(5+), the more lipophilic compound, was the most effective in protecting LDL lipids, while MnTCPP(3-) exerted the lesser protection. Mn(III)porphyrins react fast with PN ( approximately 10(5)-10(7) M(-1) s(-1)) to yield a O=Mn(IV) complex. The stoichiometry of uric acid consumption was approximately 1.7 moles per mol of PN, in agreement with reactions with both the O=Mn(IV) complex and nitrogen dioxide. A shift from an anti- to a pro-oxidant action of the Mn(III)porphyrin was observed after uric acid was significantly consumed, supporting competition reactions between LDL targets and uric acid for the O=Mn(IV) complex. Overall, the data is consistent with the catalytic reduction of PN in a cycle that involves a one electron oxidation of Mn(III) to Mn(IV) by PN followed by the reduction back to Mn(III) by uric acid. These antioxidant effects should predominate under in vivo conditions having plasma uric acid concentration range between 150 and 500 microM.

Full Text

Duke Authors

Cited Authors

  • Trostchansky, A; Ferrer-Sueta, G; Batthyány, C; Botti, H; Batinić-Haberle, I; Radi, R; Rubbo, H

Published Date

  • November 15, 2003

Published In

Volume / Issue

  • 35 / 10

Start / End Page

  • 1293 - 1300

PubMed ID

  • 14607528

Pubmed Central ID

  • 14607528

International Standard Serial Number (ISSN)

  • 0891-5849

Digital Object Identifier (DOI)

  • 10.1016/j.freeradbiomed.2003.07.004

Language

  • eng

Conference Location

  • United States