In this study, five Egyptian species were tested for their in vitro antimicrobial activities. The antimicrobial screening was carried out via disc diffusion method toward four strains of the clinical antibiotic resistant pathogens including Escherichia coli, Staphylococcus aureus, Candida albicans and Aspergillus niger. Among the methanolic extracts screened, Azadirachta indica, Tectona grandis and Ficus sycomorus showed a broad antimicrobial spectrum against three strains with inhibition zones between 13-27 mm followed by Gmelina arborea and Ficus microcarpa with inhibition zones between 11-17 mm, all plants showed no activity against Aspergillus niger except Gmelina arborea with inhibition zones 12 mm. Penicillin G was used as positive control at concentration of 100 µg/disc with inhibition zones (Staphylococcus aureus 28mm, Escherichia coli 22mm, Candida albicans 25mm and Aspergillus niger 0mm). Owing to the high activity of the methanolic extracts, these extracts were defatted via petroleum ether then were fractionated via; chloroform, ethyl acetate and n-butanol. The n-butanol of Azadirachta indica was the most active against Candida albicans (25 mm), ethyl acetate of Ficus sycomorus against Staphylococcus aureus (18 mm), n-butanol of Gmelina arborea against Staphylococcus aureus (17 mm) and n-butanol of Ficus microcarpa against Staphylococcus aureus (15 mm). These results suggest that the tested plants may be effective potential sources of natural antimicrobials, and are potent inhibitors of antibiotic resistant pathogens.
Key words: Egyptian plants, Extraction, Bioassay guided fractionation, Antimicrobial
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