The invention provides low molecular weight compounds that block the pore formed by protective antigen and inhibit anthrax toxin action. Structures of the compounds are derivatives of .beta.-cyclodextrin. Per-substituted alkylamino derivates displayed inhibitory activity, and they were protective against anthrax lethal toxin action at low micromolar concentrations. Also, the addition of one of the alkylamino derivatives to the bilayer lipid membrane with multiple PA channels caused a significant decrease in membrane conductance. Thus, the invention also provides methods for protection against anthrax toxicity.