The present disclosure provides compounds, or pharmaceutically acceptable salts thereof, for inhibiting the growth of a microbe; treating a mammal having a microbial infection, malaria, mucositis, an ophthalmic infection, an otic infection, a cancer, or a Mycobacterium infection; killing or inhibiting the growth of a Plasmodium species; inhibiting the growth of a Mycobacterium species; modulating an immune response in a mammal; or antagonizing unfractionated heparin, low molecular weight heparin, or a heparin/low molecular weight heparin derivative.