Determination of the total antioxidant capacity of food and human plasma by photochemiluminescence: Correlation with spectrophotometric (FRAP) and fluorometric (ORAC) assays

Abstract

The determination of antioxidant capacity is useful to value the quality of a food, the sum of antioxidants in a system, or the bioavailability of antioxidant compounds in the human body. The available methods determine the potential effect of antioxidant substances, present in food and in the human body, against oxidation reactions. The objective was to compare the total antioxidant capacity (TAC) of food samples and human plasma, by photochemiluminescence (PCL) in contrast to methods that quantify the oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP). Water-soluble and lipid-soluble extracts were obtained from stabilized rice bran (SRB) and Ulva clathrata flour (UCF). Plasma was obtained from blood human samples (HUP). Three samples were processed in each case. The results were analyzed with one-way analysis of variance and Pearson's correlation, p <0.05. The results of TAC measurement were PCL, SRB 246.37 ± 5.37; UCF 21.05 ± 0.41 and HUP 90.59 ± 1.17 Trolox equivalents (TE) μmol /100 g or 100 mL, p<0.05. With ORAC were: SRB 5015.62 ± 12.83; UCF 852.37 ± 3.45 and HUP 2563.31 ± 39.47 TE μmol /100 g or 100 mL, p<0.05. FRAP: SRB 519.37 ± 0.04; UCF 52.78 ± 0.01 and HUP 90.26 ± 0.01 Fe2+ equivalents (Fe2+E) µmol /100 g or 100 mL. Correlations were observed between PCL-ORAC r=0.99; and PCL-FRAP r=0.94, both statistically significant (p < 0.05). PCL showed to be a reliable and alternative method to quantify TAC, which can be applied in food and health intervention studies.