Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

Introduction: The extracts and oils from Melaleuca spp.leaves (Myrtaceae family) have been traditionally used as a topical therapeutic agent for the treatment of various skin infections. The current study aimed to evaluate the potential antimicrobial activities of the different active components of Melaleuca spp. plant as topical agents against some medically important pathogens related to the common skin infections and detection of their possible mutagenic effect. Methods: The M. alternifolia leaves were subjected to successive fractionation using different solvents with different polarities.The TTOwas extractedfrom plant leaves using steam hydro-distillation andthen subjected to GC/MS analysis to characterize its main components. The aqueous extract fraction was used to synthesize silver nanoparticles (AgNPs) via green nanotechnology. The different extracted fractions, TTO, and AgNPs were evaluated for their antimicrobial activities against representativeskin-infecting pathogen including bacteria, fungi and viruses.Furthermore, theTransmission electron microscope examination was used to characterize the synthesized AgNPs and to visualize the treated microbial cells to figure out the basic changes that may be referred to a certain mode of action.Moreover, the possible mutagenic effect of TTO and AgNPs was investigated against S. typhimurium TA89 and TA100 strains using the Ames test

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