Antimicrobial peptide with activity against Gram-positive bacteria S.epidermidis ATCC 12228 (MIC=50 uM) and S.aureus (MIC=64 ug/ml and MBC=128 ug/ml) (PubMed:28469603) (By similarity). Not active against some Gram-positive bacteria (methicillin-resistant S.aureus (MRSA), E.faecalis), Gram-negative bacterium E.coli ATCC 25922 and fungus C.albicans at concentrations up to 100 uM (PubMed:28469603) (By similarity). Can only slightly inhibit the formation of biofilm by S.aureus (minimal biofilm inhibitionconcentration MBIC=512 ug/ml, minimal biofilm eradication concentration MBEC>512 ug/ml) (PubMed:28469603). Has an anti-inflammatory effect, since it inhibits the production of the pro-inflammatory cytokines TNF-alpha and IL-1beta (By similarity). Has high activity of stimulation of insulin release, which may protect the species from being eaten by predators by causing fatal hypoglycemia (By similarity). Is not cytotoxic to cancer line cells (By similarity). Shows very low hemolysis on horse erythrocytes and moderate hemolysis on mouse erythrocytes (PubMed:28469603) (By similarity). Expressed by the skin glands. In the synthetic mutant medusin-PT1a [T58K], the Leu-50 has been modified in a D-amino acid. In medusin-PT1a, there is an increase in antimicrobial activity, and an increase in hemolytic activity. It is more potent against S.aureus and gains activity against MRSA, E.faecalis, E.coli, P.aeruginosa and C.albicans. There is an important increase in both biofilm inhibition and biofilm eradication. The primary structure of this peptide is identical to that of Medusin-TR1 (AC C0HLE1). Belongs to the frog skin active peptide (FSAP) family. Medusin subfamily.