Food Chem Toxicol, 2012 Jul 26
Antioxidant activity (AO) of commercial propolis extracts (PEs), available on Serbian market, was determined by direct current (DC) polarography.
Polarographic anodic current of 5.0 mmol L(-1) alkaline solution of H(2)O(2) was recorded at potentials of mercury dissolution. Decrease of the current was plotted against the volume of gradually added PEs. The volume of PE causing 20 % current decrease was determined from the linear part of the plot. Antioxidant activity was expressed in H(2)O(2) equivalent (HPEq), representing the volume of PE that corresponds to 1.0 mmol L(-1) H(2)O(2) decrease. Resulting HPEq ranged between 1.71 ± 0.11 and 8.00 ±0.18 μL. Range of 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity was from 0.093 ± 0.004 to 0.346 ± 0.006 %. Total phenolic content (TCP) of PE with superior AO activity was 5.31 ± 0.05 %g GAE, while the extract with the lowest activity contained 1.45 ± 0.02 %g GAE.
Antioxidant activity, determined by polarographic method, was correlated with DPPH scavenging activity (R(2) = 0.991) and TCP (R(2) = 0.985). Validity of obtained results was further confirmed using ANOVA and post-hoc Tukey HSD test.