Bulgarian propolis induces analgesic and anti-inflammatory effects in mice and inhibits in vitro contraction of airway smooth muscle

Abstract

Propolis is a bee product, which has long been used in folk medicine for the management of different diseases. In this study we evaluated the analgesic and anti-inflammatory effects of a standard ethanolic extract of Bulgarian propolis (Et-Blg) in mice and its in vitro effect on airway smooth muscle. Et-Blg inhibited acetic acid-induced abdominal contortions with an ID50 = 7.4 ± 0.7 mg.kg-1. In the formalin test, the extract caused a significant reduction in pain in mice treated with 100 mg.kg-1 Et-Blg during the neurogenic phase and for the inflammatory phase with all doses of the extract, with an ID50 = 2.5 ± 0.4 mg.kg-1. Et-Blg inhibited also the capsaicin-induced ear edema in mice; however, this extract was ineffective when assessed in the tail-flick and hot-plate thermal assays. The analgesic effect of Et-Blg was associated with the inhibition of inflammatory responses and not to a simple irritation of nervous terminals. In vitro, this extract inhibited the contraction of trachea smooth muscle induced by histamine (IC50 = 50 ± 5 μg.mL-1), capsaicin (IC50 = 26.8 ± 3 μg.mL-1), 80 mM KCl (IC50 = 27.8 ± 3 μg.mL-1), and carbachol (IC50 = 54 ± 2 μg.mL-1).