Novel antimicrobial defensin peptides from different coleopteran insects (Coleoptera: Insecta): identification, characterisation and antimicrobial properties

Antimicrobial peptides are crucial components of the immune systems of both vertebrates and invertebrates. Here, defensins, the most studied class of antimicrobial molecules in arthropods were investigated in four coleopteran insect species: <i>Harpalus rufipes</i> (DeGeer, 1774), <i>Mylabris quadripunctata</i> (Linnaeus, 1767), <i>Sphaeridium marginatum</i> (Linnaeus, 1758), and <i>Ocypus mus</i> (Brullé, 1832). The peptides synthesized with over 95% purity and their antimicrobial activities were evaluated by MIC test method. As a result, it was determined that <i>Mylabris quadripunctata</i> defensin (MqDef) showed high antimicrobial activity against <i>Staphylococcus aureus</i> and MRSA, whereas <i>Sphaeridium marginatum</i> (SmDef) and <i>Harpalus rufipes</i> (HrDef) defensins against <i>Candida tropicalis</i>.