Antioxidant and antimicrobial activities of extracts from fruits of Nitraria sibirica Pall. in vitro

Nitraria sibirica Pall. (Zygophyllaceae) are traditionally utilized as food or folk medicine in China. To provide the basis for exploiting Nitraria resources and developing a natural food antiseptic, we determined the in vitro radical scavenging activity and antimicrobial activities of N. sibirica fruits. For the radical scavenging activity study, fruits of N. sibirica were extracted by 70% acetone, ether, ethyl acetate and n-butanol successively. The DPPH and ABTS experiment showed that water phase extract had the highest radical scavenging activity. We have isolated isorhamnetin-3-O-β-L-rutinoside and isorhamnetin-3-O-rutinoside-7-O-glucoside from the water phase fraction, both of which are radical scavenging compounds. For antimicrobial activity study, fruits were extracted with 95% ethanol, petroleum ether, chloroform and n-butanol successively. Except n-butanol, all extracts exhibit antibacterial activity against three tested bacteria species (E. coli, B. subtilis, S. aureus). We have determined the MICs against the three bacterial species of ethyl acetate extract, which possessed the highest antibacterial activity.