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Inhibition of metmyoglobin/H2O2-dependent low density lipoprotein lipid peroxidation by naturally occurring phenolic acids.
Biochem Pharmacol. 1996 Feb 23; 51(4):395-402.BP

Abstract

The ferrylmyoglobin <==> metmyoglobin redox transitions promoted by hydrogen peroxide and dietary phenolic acids and their potential role in the oxidation of LDL were studied. The use of parinaric acid incorporated in LDL as a probe for radicals (detected by fluorescence quenching of the probe) revealed an oxidative stress inside LDL shortly (< 1 min) after addition of hydrogen peroxide to metmyoglobin in the aqueous phase outside the particle, reflecting an efficient access of the oxidant to LDL lipids. However, the propagation step of peroxidation only occurs after a lag phase, as detected by the kinetics of oxygen consumption. Triton X-100 decreases but does not suppress the lag phase of oxidation. Addition of metmyoglobin (without peroxide) to LDL was not followed by significant oxidation during the time of the experiment, unless Triton X-100 was present in the medium. When dietary phenolic acids were present in the medium before peroxide addition, an inhibition of parinaric acid fluorescence quenching and oxygen consumption was recorded as a function of concentration and substitution pattern on the phenol ring of the phenolic acids. This was associated with a conversion of ferrylmyoglobin to metmyoglobin. The results indicate that the naturally occurring phenolic acids prevent ferrylmyoglobin-dependent LDL oxidation in a way strongly dependent on the substitution pattern on the phenol ring. Among the phenolic compounds studied, the o-dihydroxy derivatives of cinnamic and benzoic acids (caffeic, chlorogenic, and protocatechuic acids), in a molar ratio of 1 to metmyoglobin, efficiently blocked LDL oxidation initiated by ferrylmyoglobin. Replacement of one OH group from catecholic structure with an H (p-coumaric acid) or methoxy group (ferulic acid) decreased the antioxidant activity. Also, the catechol structure fused in heterocyclic rings with adjacent carbonyl groups (ellagic acid) resulted in decreased antioxidant activity. These observations correlate with the efficiency of phenolic acids to reduce ferrylmyoglobin to metmyoglobin. Therefore, the protection of LDL against oxidation is assigned to the reduction of the oxoferryl moiety of the hemoprotein to the ferric form. Additionally, it is suggested that an access constraint of oxidants plays a minor role in the ferrylmyoglobin-induced oxidation against LDL.

Authors+Show Affiliations

Laboratório de Bioquímica, Faculdade de Farmácia, Universidade de Coimbra, Portugal.No 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

8619883

Citation

Laranjinha, J, et al. "Inhibition of metmyoglobin/H2O2-dependent Low Density Lipoprotein Lipid Peroxidation By Naturally Occurring Phenolic Acids." Biochemical Pharmacology, vol. 51, no. 4, 1996, pp. 395-402.
Laranjinha J, Vierira O, Almeida L, et al. Inhibition of metmyoglobin/H2O2-dependent low density lipoprotein lipid peroxidation by naturally occurring phenolic acids. Biochem Pharmacol. 1996;51(4):395-402.
Laranjinha, J., Vierira, O., Almeida, L., & Madeira, V. (1996). Inhibition of metmyoglobin/H2O2-dependent low density lipoprotein lipid peroxidation by naturally occurring phenolic acids. Biochemical Pharmacology, 51(4), 395-402.
Laranjinha J, et al. Inhibition of metmyoglobin/H2O2-dependent Low Density Lipoprotein Lipid Peroxidation By Naturally Occurring Phenolic Acids. Biochem Pharmacol. 1996 Feb 23;51(4):395-402. PubMed PMID: 8619883.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Inhibition of metmyoglobin/H2O2-dependent low density lipoprotein lipid peroxidation by naturally occurring phenolic acids. AU - Laranjinha,J, AU - Vierira,O, AU - Almeida,L, AU - Madeira,V, PY - 1996/2/23/pubmed PY - 1996/2/23/medline PY - 1996/2/23/entrez SP - 395 EP - 402 JF - Biochemical pharmacology JO - Biochem Pharmacol VL - 51 IS - 4 N2 - The ferrylmyoglobin <==> metmyoglobin redox transitions promoted by hydrogen peroxide and dietary phenolic acids and their potential role in the oxidation of LDL were studied. The use of parinaric acid incorporated in LDL as a probe for radicals (detected by fluorescence quenching of the probe) revealed an oxidative stress inside LDL shortly (< 1 min) after addition of hydrogen peroxide to metmyoglobin in the aqueous phase outside the particle, reflecting an efficient access of the oxidant to LDL lipids. However, the propagation step of peroxidation only occurs after a lag phase, as detected by the kinetics of oxygen consumption. Triton X-100 decreases but does not suppress the lag phase of oxidation. Addition of metmyoglobin (without peroxide) to LDL was not followed by significant oxidation during the time of the experiment, unless Triton X-100 was present in the medium. When dietary phenolic acids were present in the medium before peroxide addition, an inhibition of parinaric acid fluorescence quenching and oxygen consumption was recorded as a function of concentration and substitution pattern on the phenol ring of the phenolic acids. This was associated with a conversion of ferrylmyoglobin to metmyoglobin. The results indicate that the naturally occurring phenolic acids prevent ferrylmyoglobin-dependent LDL oxidation in a way strongly dependent on the substitution pattern on the phenol ring. Among the phenolic compounds studied, the o-dihydroxy derivatives of cinnamic and benzoic acids (caffeic, chlorogenic, and protocatechuic acids), in a molar ratio of 1 to metmyoglobin, efficiently blocked LDL oxidation initiated by ferrylmyoglobin. Replacement of one OH group from catecholic structure with an H (p-coumaric acid) or methoxy group (ferulic acid) decreased the antioxidant activity. Also, the catechol structure fused in heterocyclic rings with adjacent carbonyl groups (ellagic acid) resulted in decreased antioxidant activity. These observations correlate with the efficiency of phenolic acids to reduce ferrylmyoglobin to metmyoglobin. Therefore, the protection of LDL against oxidation is assigned to the reduction of the oxoferryl moiety of the hemoprotein to the ferric form. Additionally, it is suggested that an access constraint of oxidants plays a minor role in the ferrylmyoglobin-induced oxidation against LDL. SN - 0006-2952 UR - https://www.unboundmedicine.com/medline/citation/8619883/Inhibition_of_metmyoglobin/H2O2_dependent_low_density_lipoprotein_lipid_peroxidation_by_naturally_occurring_phenolic_acids_ L2 - https://linkinghub.elsevier.com/retrieve/pii/000629529502171X DB - PRIME DP - Unbound Medicine ER -