Abstract

Out of a hundred horses, fecal samples Escherichia coli was isolated from 37 samples of
different ages, The isolated samples had been used to examine the effect of peganum
harmaline on isolated E.coli in vitro and in vivo.
The goal of this research was to determine the antimicrobial activity of peganum
harmaline extract by means of (ethanol: methanol 1:1) in opposition to Escherichia coli at
various 40,20, 10, 5, 2,5, 1,25 and 0,625 mg/ml concentrations in each plastic and glass
tube. The values of MIC (minimum inhibitory concentration) and MBC (minimum
bactericidal concentration) for the extract against E.coli were equal to (0.625 mg/ml) for
MIC and (10 mg/ml) for MBC on bacteria which cultured on glass tube while the MIC
value was 40 mg/ml and MBC was10 mg/ml on plastic tube. The effect of Peganum
harmaline on the formation of E.coli biofilm was investigated and the biofilm inhibitory
concentrations were 40-6.25mg / ml in vitro. In vivo, a group of laboratory mice used, the
LD50 of peganum harmaline extract was tested orally by up and down method and found
to be 1030 mg/kg body weight, the extract used as 103 mg/kg bodyweight treatment after
causing E.coli infection at 1×108 CFU/ml in laboratory mice the treated persist for two
weeks in group one and three weeks in the second group as well as three week treated in
the third group from the second days after infection while the control group left without
treated and the mice sacrificed after second, third and fifth days of infection. The result
shows histopathological changes in all treated groups, especially in the third group and
that refers to the antibacterial effect of the peganum harmaline ethanolic extract when
compared to the infected control group.