The search for new membrane-active peptides is carried out , either by de novo design or from natural sources, including genome mining and drug repurposing. Optimization by SAR studies. Elucidation of their mechanism of action and targets involved; if feasible further validation by a variety of biophysical and biochemical techniques. Recombinant production. To date we have successfully defined the leishmanicidal activity of cecropin-melittin peptides  gramicidin S analogues ,  and of AS-48, histatin 5, and eosinophils cationic protein as paradigms of antimicrobial polypeptide with intracellular targets.