Effect of honey on purified equine myeloperoxidase activity and superoxide radical production in activated Polymorphonuclear neutrophils

Three Algerian honey samples(nectar honey, mixed honey and honeydew honey) were analysed for their total phenolic content (TPC) using the Folin-Ciocalteu reagent and total flavonoid content (TFC) by the aluminium chloride method. The antioxidant activity was tested both against reactive oxygen species (ROS) produced by phorbol 12-myristate 13-acetate (PMA)-stimulated equine polymorphonuclear neutrophils (PMNs) and on purified equine myeloperoxidase (MPO) enzyme activity. The ROS production by stimulated PMNs was measured by lucigenin-enhanced chemiluminescence. Specific immunological extraction followed by enzymatic detection (SIEFED) was used to measure specifically the activity of equine MPO. Nectar honey, mixed honey and honeydew honey had TPCs of 59.52 +/- 1.31, 68.36 +/- 1.20 and 122.76 +/- 4.20mg gallic acid equivalents (GAE)/100g honey, respectively (mean +/- SD). As for the TPC, the highest TFC was observed for honeydew honey [20.55 +/- 0.72mg catechine equivalents (CE)/100mg honey], followed by mixed honey (7.47 +/- 0.07CE/100mg honey) and nectar honey (4.80 +/- 0.08CE/100mg honey). All the tested honeys displayed a dose-dependent inhibitory effect on the oxidant activities of PMNs. By the SIEFED technique, it was shown that most of the honeys interact directly with MPO: the light honeys (nectar honey and mixed honey) were inhibitors of MPO activity, while the dark honey had less inhibiting effect and even behaved as an enhancer of MPO activity at high concentrations.