Effects of hop extracts on nasal rubbing and sneezing in BALB/c mice

Abstract

The effects of hop extracts (Humulus lupulus L.) on histamine release from rat peritoneal mast cells and human basophilic KU812 cells were studied. Hop water extract (HWE) and XAD-4 50% methanol fraction of HWE (MFH) inhibited histamine release from rat mast cells induced by compound 48/80 at concentrations of 100 and 10 μg/ml, respectively. Almost the same findings were observed with A23187-induced histamine release from KU812 cells. Next, we studied the effects of hop extracts on antigen-induced nasal rubbing and sneezing in sensitized BALB/c mice. HWE caused a significant inhibition of nasal rubbing and sneezing at a dose of 500 mg/kg. MFH also inhibited nasal rubbing and sneezing dose-dependently. A significant difference was observed from 100 mg/kg in nasal rubbing and 200 mg/kg in sneezing. The effects of both extracts became clear after repeated administration. HWE and MFH significantly inhibited both nasal rubbing and sneezing, respectively, after consecutive treatment for 15 d at smaller doses compared with single administration. This finding indicates that the active component of hop is included in MFH, which was absorbed to Amberlite XAD-4 and eluted with 50% methanol. These results clearly demonstrated that hop extracts may be effective in the relief of symptoms of allergic rhinitis. © 2006 Pharmaceutical Society of Japan.