Methods for the In vitro examination of the antibacterial and cytotoxic activities of antimicrobial peptides

Antimicrobial peptides (AMPs) represent an interesting class of molecules with expanding properties. Nature is the primary source of AMPs since they are produced by most living organisms including prokaryotes, plants, and animals. Thanks to their hundreds of thousands of species on earth, insects are one of the most abundant and varied resources of AMPs. Among these, many families have already been well characterized while new AMPs are continuously discovered. In this chapter, the main methods for the in vitro evaluation of the biological properties of AMPs are described. In particular, to examine the antimicrobial activity, the inhibition zone assay and the techniques for the determination of the minimal inhibitory concentration and the bactericidal concentration are reported in detail. For the evaluation of the possible cytotoxic effect toward mammalian cells, the hemolytic test and the colorimetric assay based on the reduction of 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide are also described.