Theoretical and experimental study of the antioxidant capacity of 5-O-caffeoylquinic, quinic and caffeic acids based on electronic and structural properties

URANGA, JORGE; PODIO, N.S.; WUNDERLIN, D.A.; SANTIAGO, A.N.

Chemistry Select

Springer

Año: 2016 vol. 1 p. 4113 - 4120

2365-6549

The aim ofthis study was to elucidate the structural and electronic factors thatdetermine the antioxidant capacity of 5-O-caffeoylquinic, caffeic and quinicacids under different experimental conditions. Antioxidant capacity wasmeasured using different in vitroassays (TEAC, DPPH and FRAP), involving diverse mechanisms of antioxidantaction, namely, radical scavenging or reduction. The mechanisms of thesereactions were analyzed by a theoretical study using the DFT theory. Resultsallow relating in vitro antioxidantcapacity of these three compounds with their chemical structures. Theantioxidant capacity experimentally observed for these three acids wasinterpreted considering the reaction mechanism involved, the nature andstability of the intermediate formed, the formation and reaction of secondarycompounds, and the effect of the reaction medium. The main goal of this reportis presenting a theoretical analysis of reactions implicated in the antioxidantcapacity, identifying the causes that increase or decrease such property. Thus,we present a complete quantum mechanical description of the antioxidantproperties involved with these three compounds, considering equilibriums and secondaryoxidations involved.