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Phenolic antioxidants and the protection of low density lipoprotein from peroxynitrite-mediated oxidations at physiologic CO2.
J Agric Food Chem. 2004 May 19; 52(10):2866-74.JA

Abstract

Dietary phenolic antioxidants have been shown to prevent LDL modifications mediated by several physiologic oxidants including peroxynitrite. However, more recent data demonstrated that CO(2) affected the fate of peroxynitrite in biological fluids and significantly reduced peroxynitrite scavenging by polyphenols, raising doubts concerning their antioxidant activity. We found that the oxidation of LDL lipids mediated by peroxynitrite decreased in the presence of bicarbonate, while Trp oxidation and 3-nitroTyr formation increased, suggesting a redirection of peroxynitrite reactivity toward the protein moiety. We therefore evaluated the protective activity of some phenolic antioxidants (quercetin, oleuropein, resveratrol, (+)-catechin, (-)-epicatechin, tyrosol, alpha- and gamma-tocopherol, ascorbate) on peroxynitrite-mediated oxidation of LDL aromatic residues. Some of these phenols protected LDL Trp from oxidation better than ascorbate or alpha-tocopherol, although protection at 100 microM did not exceed 30-40%. However, the same phenolic antioxidants were more active in inhibiting 3-nitroTyr formation and those with a catechin structure provided significant protection (IC(50%) 40-50 microM). Red wine, a polyphenol-rich beverage, showed a protective effect comparable to that of the most active phenolic antioxidants. Direct EPR studies showed that bicarbonate significantly increased the peroxynitrite-dependent formation of O-semiquinone radicals in red wine, supporting the hypothesis that polyphenols are efficient scavengers of radicals formed by peroxynitrite/CO(2). Ascorbate was a poor inhibitor of peroxynitrite/CO(2)-induced LDL tyrosine nitration, but the simultaneous addition to the most active polyphenols halved their IC(50%). In conclusion, although cooperation with other antioxidants can further decrease the IC(50%) of polyphenolics, as demonstrated for ascorbate, their antioxidant activity appears to occur at concentrations at least 1 order of magnitude higher than their bioavailability.

Authors+Show Affiliations

Laboratorio di Biologia Cellulare, Istituto Superiore di Sanità, 00161 Roma, Italy.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15137827

Citation

Ferroni, Flavia, et al. "Phenolic Antioxidants and the Protection of Low Density Lipoprotein From Peroxynitrite-mediated Oxidations at Physiologic CO2." Journal of Agricultural and Food Chemistry, vol. 52, no. 10, 2004, pp. 2866-74.
Ferroni F, Maccaglia A, Pietraforte D, et al. Phenolic antioxidants and the protection of low density lipoprotein from peroxynitrite-mediated oxidations at physiologic CO2. J Agric Food Chem. 2004;52(10):2866-74.
Ferroni, F., Maccaglia, A., Pietraforte, D., Turco, L., & Minetti, M. (2004). Phenolic antioxidants and the protection of low density lipoprotein from peroxynitrite-mediated oxidations at physiologic CO2. Journal of Agricultural and Food Chemistry, 52(10), 2866-74.
Ferroni F, et al. Phenolic Antioxidants and the Protection of Low Density Lipoprotein From Peroxynitrite-mediated Oxidations at Physiologic CO2. J Agric Food Chem. 2004 May 19;52(10):2866-74. PubMed PMID: 15137827.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Phenolic antioxidants and the protection of low density lipoprotein from peroxynitrite-mediated oxidations at physiologic CO2. AU - Ferroni,Flavia, AU - Maccaglia,Alessandro, AU - Pietraforte,Donatella, AU - Turco,Laura, AU - Minetti,Maurizio, PY - 2004/5/13/pubmed PY - 2004/7/9/medline PY - 2004/5/13/entrez SP - 2866 EP - 74 JF - Journal of agricultural and food chemistry JO - J. Agric. Food Chem. VL - 52 IS - 10 N2 - Dietary phenolic antioxidants have been shown to prevent LDL modifications mediated by several physiologic oxidants including peroxynitrite. However, more recent data demonstrated that CO(2) affected the fate of peroxynitrite in biological fluids and significantly reduced peroxynitrite scavenging by polyphenols, raising doubts concerning their antioxidant activity. We found that the oxidation of LDL lipids mediated by peroxynitrite decreased in the presence of bicarbonate, while Trp oxidation and 3-nitroTyr formation increased, suggesting a redirection of peroxynitrite reactivity toward the protein moiety. We therefore evaluated the protective activity of some phenolic antioxidants (quercetin, oleuropein, resveratrol, (+)-catechin, (-)-epicatechin, tyrosol, alpha- and gamma-tocopherol, ascorbate) on peroxynitrite-mediated oxidation of LDL aromatic residues. Some of these phenols protected LDL Trp from oxidation better than ascorbate or alpha-tocopherol, although protection at 100 microM did not exceed 30-40%. However, the same phenolic antioxidants were more active in inhibiting 3-nitroTyr formation and those with a catechin structure provided significant protection (IC(50%) 40-50 microM). Red wine, a polyphenol-rich beverage, showed a protective effect comparable to that of the most active phenolic antioxidants. Direct EPR studies showed that bicarbonate significantly increased the peroxynitrite-dependent formation of O-semiquinone radicals in red wine, supporting the hypothesis that polyphenols are efficient scavengers of radicals formed by peroxynitrite/CO(2). Ascorbate was a poor inhibitor of peroxynitrite/CO(2)-induced LDL tyrosine nitration, but the simultaneous addition to the most active polyphenols halved their IC(50%). In conclusion, although cooperation with other antioxidants can further decrease the IC(50%) of polyphenolics, as demonstrated for ascorbate, their antioxidant activity appears to occur at concentrations at least 1 order of magnitude higher than their bioavailability. SN - 0021-8561 UR - https://www.unboundmedicine.com/medline/citation/15137827/Phenolic_antioxidants_and_the_protection_of_low_density_lipoprotein_from_peroxynitrite_mediated_oxidations_at_physiologic_CO2_ L2 - https://dx.doi.org/10.1021/jf034270n DB - PRIME DP - Unbound Medicine ER -