Effects of Turkish propolis extract on secretion of polymorphonuclear elastase following respiratory burst

Propolis is a natural, resinous, hive product with various bioactive properties. Polymorphonuclear leukocytes (PMNLs) use both oxygen-dependent (respiratory burst) and oxygen-independent mechanisms (releasing proteolytic enzymes such as elastase) to destroy infectious agents. The in vitro effects of dimethyl sulfoxide (DMSO) extract of Turkish propolis on the secretion of PMN elastase from PMNLs following respiratory burst was studied. Phorbol myristate acetate was used to stimulate respiratory burst. The Flow Cytometric CellProbe Oxidative Burst Test was used to determinate if respiratory burst occurred or not and what its severity was after a 4 h incubation with propolis extracts (0 mg/mL, 0.625 mg/mL, 1.25 mg/mL, 2.5 mg/mL, and 5 mg/mL). PMN elastase activity following respiratory burst was determined by Flow Cytometric CellProbe Elastase Test. At the 5 mg/mL concentration, the percentages of fluorescence positivities of DCFH, PMA Oxidative Burst Test were observed as 28 ± 0.316% and 27 ± 0.374% for untreated and PMA-stimulated PMNLs, respectively. At the concentration of 5 mg/mL, percentage of fluorescence positivities of RGES-Elastase Test were observed as 17.5 ± 0.412% and 5.6 ± 0.316% for untreated and PMA-stimulated PMNLs, respectively. It was concluded that DMSO extracts of Turkish propolis may exhibit anti-inflammatory activities by reducing respiratory burst and secreting PMN elastase.