Prospecting for Antibacterial Compounds from A Basidiomycete JO5191

Abstract

The need for new antibacterial compounds with different modes of action to manage drug-resistant bacterial strains is urgent. The molecular basis of most antimicrobial agents is now fairly well known and thus it is now possible to develop new compounds with improved antimicrobial properties. Though there are several drug targets that have been identified and upon which most antibacterial agents act. there is still great need and potential to prospect from novel sources for new drug candidates. Basidiomyeetes have proved to be excellent producers of secondary metabolites with vast activities. preliminary screening of nude extracts from a basidiomyccte .JO5l9l, revealed strong antibacterial activity against two Gram-negative bacteria: Escherichia coli and Salmonella typhimarium. Thls research project involved the purification of the compounds using column chromatography and semi preparative HPLC followed by structure elucidation of the compounds responsible for the observed antibacterial activity. The fungus was cultivated in 25 replicates of 1 liter~scale in nutrient liquid media for 22 days and crude extracts prepared from both the myccliuin and the culture filtrate immediately after stopping growth. The crude extracts were screened for anti- bacterial activity and the compounds purified by bioassay-guided fractionation on silica gel and reverse phase high-pressure liquid chromatography. The chemical structures of the purified compound(s) were determined using spectroscopic techniques: infrared (IR), nuclear magnetic resonance (NMR) in conjunction Willi MS and CD and found to be flavanones. The antibacterial activities were determined by the calculation of minimum inhibitory concentrations (MIC), which were found to be in the range 3ig/ml - l2tg/ml. agreeing considerably well with those from the literature.