Ansamycins is a family of secondary metabolites that show antimicrobial activity against many gram-positive and some gram-negative bacteria and includes various compounds among which: streptovaricins and rifamycins . In addition, these compounds demonstrate antiviral activity towards bacteriophages and poxviruses. Structure They are named ansamycins—ansa from the Latin for handle—because of their unique structure which comprises an aromatic moiety bridged by an aliphatic chain . Th… (More on Ansamycin)