ABSTRACT
Geum kokanicum Regel et schmath, a member of Rosaceae family, is an endemic perennial rhizomatous plant of Iran. This plant has a consideration attention in the treatment of diarrhea and other gastrointestinal disorders. In this study, the anti bacterial effects of total extract and fractions of rhizome of plant were investigated. Rhizomes of G. Kokanicum were collected in June 2006 from Bojnourd [khorasan province]. The dried rhizomes were extracted with ethanol to prepare the total extract. Another part of the rhizomes was separately extracted with petrolium ether, dichloromethane, methanol and water successively in order to obtain different fractions. The antibacterial effects of total extract and fractions were investigated with disc diffusion method. The results shows Staphylococcus aureus were susceptible against total extract and methanol fraction. This fraction [10mg/disc] was indicated the largest zone diameters [19mm]. The MIC Values of total extract was investigated. Among the bacterial strains, Staphylococcus epidermitus demonstrated high sensitivity to the total extract of G. kokanicum [0.125mg/ml]. The zone diameters of total extract was 18 mm on S. aureus in 10 mg/disc. Phytochemical analysis of total extract was shown the large amounts of tanan compounds. We suspect the antibacterial effect is for tanan compounds. This was demonstrated by bioautography method analysis of tanan part isolated form methanol fraction