Study on chemical composition, anti-inflammatory and anti-microbial activities of extracts from Chinese pear fruit (Pyrus bretschneideri Rehd.).

Pyrus bretschneideri Rehd. belongs to the genus Pyrus, a member of Rosaceae family. It is a routine edible fruit, and also used as a folk medicine to treat cough, eliminate constipation, and relieve alcoholism. In order to clarify the active compounds of P. bretschneideri, the phytochemical study were performed. Five compounds were isolated and identified as 2β,19α-dihydroxy ursolic acid, quercitrin, dibutyl phthalate, diisobutyl phthalate and α-amyrin. Additionally, we investigate the anti-inflammatory and anti-microbial effects of the fractions of P. bretschneideri partitioned with petroleum ether, ethyl acetate and n-butanol, respectively. In the carrageenan-induced rat paw edema test, the EtOAc fraction showed the strongest inhibition of edema formation 0.5-5 h after edema induction, followed by n-butanol. EtOAc also displayed potent anti-inflammatory activity against xylene-induced ear edema (22.03% and 43.69%, respectively) and acetic acid-induced extravasation of Evan's blue dye (39.58% and 49.92%, respectively) at the dose of 200 and 400 mg/kg. While, the anti-microbial results showed that ethyl acetate and n-butanol fractions exhibited strong activity against the bacteria strains. Moreover, 2β,19α-dihydroxy ursolic acid, α-amyrin and quercitrin could significantly inhibit the ear edema induced by xylene at the dose of 20 mg/kg, and exhibited moderate anti-microbial activities against the bacteria strains.