Medicinal plants have been the source of remedies for healthcare for the majority of people in Africa. In Sudan there is little scientific information available on the nature and chemical composition of the most of these medicinal plants.This book has focused mainly on preliminary screening of antibacterial and antiviral activity of some Sudanese medicinal plants as well as phytochemical studies of three selected species; Diospyros mespiliformis, Croton zambesicus and Caralluma retrospiciens. Isolation and characterization of some chemical constituents in the three species,were comprehensively explained, the techniques employed in the isolation of the compounds and the elucidation of their structure are based on chromatographic and spectroscopic data. Following their isolation, the book has highlighted the antibacterial, cytotoxicity, phytotoxicity, antioxidant activities, alpha-glucosidase enzyme inhibition, in addition to acetylcholinesterase and butyrylcholinesterase inhibiting activities of the isolated compounds.