Pseudin is a peptide derived from Pseudis paradoxa. ^[1] Pseudins have some antimicrobial function. ^{[2] [3]}

There are several different forms:

• pseudin-1 ^[4]
• pseudin-2 -- has been proposed as a treatment for type 2 diabetes. ^{[5] [6]}
• pseudin-4 ^[7]

Pseudin-2 is the most abundant version of the pseudins found on the skin of the paradoxical frog. ^[8] The primary sequence reads as GLNALKKVFQGIHEAIKLINNHVQ. Its secondary/tertiary structure consists of one cationic amphipathic α-helix. ^{[8] [9]}

Pseudin-2 was shown to have potent antibacterial activity, but a lower cytotoxicity. ^[8] The cytotoxicity of a peptide can be measured by its effect on human erythrocytes. ^[9] It takes a lower concentration of Pseudin-2 to kill bacteria or fungi such as E. coli, S. aureus, and C. albicans than to kill human erythrocytes. ^[8] It is hypothesized that Pseudin-2 binding to the cell membrane of the bacteria results in a conformational change in which the peptide forms an α-helical shape, which allows it to perform cell lysis by inserting itself in the hydrophobic portion of the membrane. ^{[8] [9]} This mechanism is applicable to similar amphipathic α-helical peptides created by many frog species, although most of these peptides aren't very potent against bacteria. ^[10] By increasing the cationicity and amphipathic nature of the molecule, it is possible to create analogues of Pseudin-2 that are even more selective towards bacteria. This is done by substituting leucine residues with lysine residues and glycine residues with proline residues, which results in two shorter α-helices (linked by the substituted proline) that are more attuned to penetrating bacterial cell membranes. ^[9]

• Exenatide

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