Tags

Type your tag names separated by a space and hit enter

Interactive effects of polyphenols, tocopherol and ascorbic acid on the Cu2+-mediated oxidative modification of human low density lipoproteins.
Eur J Nutr 2005; 44(7):422-8EJ

Abstract

BACKGROUND

Only limited knowledge is available about any interactions between phenolic compounds and other antioxidants in inhibiting LDL oxidation. Many foods and beverages contain high levels of phenolic compounds; therefore, these compounds should not be considered in isolation from each other.

AIM OF THE STUDY

The aim of this study was to examine the structure-antioxidant activity relationship of quercetin, caffeic acid, epicatechin, hesperetin and phloretin as well as alpha-tocopherol and ascorbic acid through their ability to interact with copper ions.

METHODS

Isolated human LDL were incubated with single antioxidants or a combination of two and the kinetics of lipid peroxidation were assessed by measurement of conjugated diene formation (lag phase) via monitoring the absorbance at 234 nm after addition of copper ions. In addition, the degree of oxidation of the LDL protein moiety was followed by tryptophan fluorescence and carbonyl content measurements.

RESULTS

Alpha-tocopherol and ascorbic acid showed a lower antioxidant activity in all test systems as compared to polyphenols at equimolar concentrations. Quercetin was the most effective compound in all three systems (p < 0.001 for lag phase and carbonyl content determination). A significant (p < 0.001) prolongation of the lag phase was found when combinations of ascorbic acid/quercetin, ascorbic acid/epicatechin, epicatechin/caffeic acid, and quercetin/epicatechin were tested as compared to the sum of the individual effects. Concerning the effects on LDL protein oxidation, the results from carbonyl content and the tryptophan fluorescence measurements showed that the combination of quercetin and caffeic acid revealed the strongest inhibitory effect (p < 0.001 carbonyl content; p < or = 0.002 tryptohan fluorescence) on protein oxidation which was higher than the effect of the single compounds.

CONCLUSIONS

The results of the present study indicate that a combination of different antioxidants can be superior to the action of single antioxidants in protecting LDL lipid and protein moiety against oxidation. However, the substances may act by different antioxidative mechanisms, which are not necessarily complementary.

Authors+Show Affiliations

Dept. of Food and Nutrition Technical, University of Munich, Freising-Weihenstephan, Germany. yeomans@web.deNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

15827683

Citation

Yeomans, Vera C., et al. "Interactive Effects of Polyphenols, Tocopherol and Ascorbic Acid On the Cu2+-mediated Oxidative Modification of Human Low Density Lipoproteins." European Journal of Nutrition, vol. 44, no. 7, 2005, pp. 422-8.
Yeomans VC, Linseisen J, Wolfram G. Interactive effects of polyphenols, tocopherol and ascorbic acid on the Cu2+-mediated oxidative modification of human low density lipoproteins. Eur J Nutr. 2005;44(7):422-8.
Yeomans, V. C., Linseisen, J., & Wolfram, G. (2005). Interactive effects of polyphenols, tocopherol and ascorbic acid on the Cu2+-mediated oxidative modification of human low density lipoproteins. European Journal of Nutrition, 44(7), pp. 422-8.
Yeomans VC, Linseisen J, Wolfram G. Interactive Effects of Polyphenols, Tocopherol and Ascorbic Acid On the Cu2+-mediated Oxidative Modification of Human Low Density Lipoproteins. Eur J Nutr. 2005;44(7):422-8. PubMed PMID: 15827683.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Interactive effects of polyphenols, tocopherol and ascorbic acid on the Cu2+-mediated oxidative modification of human low density lipoproteins. AU - Yeomans,Vera C, AU - Linseisen,Jakob, AU - Wolfram,Günther, Y1 - 2005/04/15/ PY - 2003/09/30/received PY - 2004/10/25/accepted PY - 2005/4/14/pubmed PY - 2006/4/21/medline PY - 2005/4/14/entrez SP - 422 EP - 8 JF - European journal of nutrition JO - Eur J Nutr VL - 44 IS - 7 N2 - BACKGROUND: Only limited knowledge is available about any interactions between phenolic compounds and other antioxidants in inhibiting LDL oxidation. Many foods and beverages contain high levels of phenolic compounds; therefore, these compounds should not be considered in isolation from each other. AIM OF THE STUDY: The aim of this study was to examine the structure-antioxidant activity relationship of quercetin, caffeic acid, epicatechin, hesperetin and phloretin as well as alpha-tocopherol and ascorbic acid through their ability to interact with copper ions. METHODS: Isolated human LDL were incubated with single antioxidants or a combination of two and the kinetics of lipid peroxidation were assessed by measurement of conjugated diene formation (lag phase) via monitoring the absorbance at 234 nm after addition of copper ions. In addition, the degree of oxidation of the LDL protein moiety was followed by tryptophan fluorescence and carbonyl content measurements. RESULTS: Alpha-tocopherol and ascorbic acid showed a lower antioxidant activity in all test systems as compared to polyphenols at equimolar concentrations. Quercetin was the most effective compound in all three systems (p < 0.001 for lag phase and carbonyl content determination). A significant (p < 0.001) prolongation of the lag phase was found when combinations of ascorbic acid/quercetin, ascorbic acid/epicatechin, epicatechin/caffeic acid, and quercetin/epicatechin were tested as compared to the sum of the individual effects. Concerning the effects on LDL protein oxidation, the results from carbonyl content and the tryptophan fluorescence measurements showed that the combination of quercetin and caffeic acid revealed the strongest inhibitory effect (p < 0.001 carbonyl content; p < or = 0.002 tryptohan fluorescence) on protein oxidation which was higher than the effect of the single compounds. CONCLUSIONS: The results of the present study indicate that a combination of different antioxidants can be superior to the action of single antioxidants in protecting LDL lipid and protein moiety against oxidation. However, the substances may act by different antioxidative mechanisms, which are not necessarily complementary. SN - 1436-6207 UR - https://www.unboundmedicine.com/medline/citation/15827683/Interactive_effects_of_polyphenols_tocopherol_and_ascorbic_acid_on_the_Cu2+_mediated_oxidative_modification_of_human_low_density_lipoproteins_ L2 - https://dx.doi.org/10.1007/s00394-005-0546-y DB - PRIME DP - Unbound Medicine ER -