Membrane-active amphiphilic β-cyclodextrin derivatives with poly-amino groups and an alkyl chain tail were created as anti-microbial peptide polymyxins. Although the molecule is relatively hydrophilic, the hydrophobic chain tail attached locally on the β-cyclodextrin molecule disrupted the bacterial membrane without destroying the animal cell, resulting in the avoidance of unfavourable hemolytic activity against red blood cells and the achievement of selective anti-bacterial activity.