These cysteine-rich antibacterial peptides are primarily active against Gram-positive bacteria and fungi in vitro.

Studies have shown that the cysteine-bridge disulfide bonds are not required for antimicrobial activity,[8] similar to findings in mammalian defensins.

[9] Furthermore, it was also shown that the N-terminal helix region in arthropod or insect defensins is also not required for antimicrobial activity of these peptides.

[11] Defensins of mammals display anti-cancer activities in vitro,[13] and down-regulation of human beta-defensin 1 is associated with increased risk of prostate cancer and clear-cell carcinomas.

[15][16] Overactive immune signalling is also implicated in age-associated neurodegeneration,[17] and overexpression of defensin leads to increased degradation of brain tissue.