Evaluation of the in vivo anti-inflammatory effects of extracts from Pyrus bretschneideri Rehd.

Pyrus bretschneideri Rehd., as a pharmaceutical supplement, is widely used in northern China to treat respiratory diseases. Our previous studies showed the ethanol extract of P. bretschneideri had significant anti-inflammatory activity. To isolate and identify the active ingredients, the ethanol extract was separated into petroleum ether, ethyl acetate, n-butanol, and aqueous fractions. The bioactivity of each fraction was investigated using an in vivo model. Results showed that the ethyl acetate fraction exhibited the strongest anti-inflammatory effect. Subsequently, this fraction was subjected to separation and purification using silica gel column chromatography, C18-ODS, and recrystallization, leading to two sterols and two triterpenes, which were identified as β-sitosterol, daucosterol, oleanolic acid, and ursolic acid. Moreover, all of the isolated compounds could significantly inhibit the ear edema induced by xylene. These results indicated that P. bretschneideri had good anti-inflammatory effects and the constituents β-sitosterol, daucosterol, oleanolic acid, and ursolic acid might well account for it.