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Free radical scavenging and cytoprotective activities of phenolic antioxidants
Author(s) -
Zhang Jingli,
Stanley Roger A.,
Adaim Aselle,
Melton Laurence D.,
Skinner Margot A.
Publication year - 2006
Publication title -
molecular nutrition and food research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.495
H-Index - 131
eISSN - 1613-4133
pISSN - 1613-4125
DOI - 10.1002/mnfr.200600072
Subject(s) - chemistry , oxygen radical absorbance capacity , rutin , lipid peroxidation , quercetin , biochemistry , antioxidant , curcumin , caffeic acid , polyphenol , ferulic acid , liposome , catechin , dpph
The free radical scavenging activities of three flavonoids (quercetin, rutin and catechin) and four hydroxycinnamic acids (caffeic, ferulic, sinapic, and chlorogenic acids) were evaluated using both oxygen radical absorbance capacity (ORAC) and lipid peroxidation inhibition capacity (LPIC) assays. The cytoprotective effects of these compounds were also measured by the degree of protection against H 2 O 2 ‐induced damage of human Jurkat cells. All compounds exhibited protection against H 2 O 2 ‐mediated cytotoxicity in a dose‐dependent manner. The concentrations required to result in a 50% reduction in cell death (EC 50 value) were calculated from their dose‐response curves. These ranged from 0.15–2.65 μM. Overall, the four hydroxycinnamic acids tested were less effective than the three flavonoids, and of all compounds tested, quercetin offered the strongest protection against H 2 O 2 ‐induced cell death. A comparison of the results showed that the ability to inhibit peroxidation of lipids in a liposomal system (LPIC) correlated well with the cytoprotective activities (EC 50 ), but not with the ability to protect an aqueous fluorescent substrate in the ORAC assays. The results suggest that the behavior of antioxidants in a liposomal membrane is to some extent similar to the mechanism involved in the protection of living cells from oxidative damage.