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The antioxidant properties of theaflavins and their gallate esters — radical scavengers or metal chelators?
Author(s) -
Miller Nicholas J.,
Castelluccio Cinzia,
Tijburg Lilian,
Rice-Evans Catherine
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00780-6
Subject(s) - chemistry , theaflavin , deoxyribose , antioxidant , abts , radical , propyl gallate , gallate , aqueous solution , chelation , aqueous two phase system , autoxidation , copper , organic chemistry , scavenger , reactivity (psychology) , polyphenol , nuclear chemistry , biochemistry , dpph , medicine , dna , alternative medicine , pathology
The antioxidant properties of theaflavins and their gallate esters were studied by investigating their abilities to scavenge free radicals in the aqueous and lipophilic phases. The total relative antioxidant activities in the aqueous phase were assessed by measuring their direct ABTS ·+ radical scavenging abilities, and by their efficacies in inhibiting the degradation of deoxyribose induced by iron. The propensities for enhancing the resistance of LDL to oxidation mediated by Cu 2+ were also measured. The results show that the hierarchy of reactivity of these compounds as antioxidants is: theaflavin digallate > 3′‐monogallate=3‐monogallate > theaflavin. Spectroscopic studies show that all the compounds chelate iron and copper; enhanced absorbance in the visible region is observed in the case of the iron‐digallate complex, but not with copper.