Bioassay Guided Fractionation of an Anti-Methicillin-Resistant Staphylococcus aureus Flavonoid From Bromus inermis Leyss Inflorescences

Background: plants are considered as promising sources of new antibacterial agents as well as bioassay guided fractionation.objectives: in the present work, the antibacterial properties, especially against methicillin-resistant staphylococcus aureus (mrsa), of bromus inermis inflorescence was studied, using the bioassay guided fractionation as well as the bio-autographic method.materials and methods: the plant organic extract was prepared via maceration in methanol, followed by the fractionation using n-hexane. the extracts were subjected for minimum inhibitory concentrations (mics) against some human pathogenic bacteria via standard broth micro-dilution assay. thereafter, a bio-autographical method was applied using the high performance thin layer chromatography (hptlc) coupled with agar overlay assays for the primary characterization and identification of bioactive substance (s).results: through the bioassay guided fractionation method, the greatest antibacterial activities were related to the n-hexane extract. it was also revealed that the effective anti-mrsa agent of the assessed plant was a relatively polar substance with an mic value of about 8 ?g/ml against the tested mrsa strain (in comparison with the mic value of 32 ?g/ml for chloramphenicol).conclusions: as a result of the full range uv-vis scanning of the responsible band in the hptlc experiments (200-700 nm), the flavonoid was the most imaginable natural compound.