Urumin is a naturally occurring 27-amino acid virucidal host defense peptide against the human influenza A virus. It was discovered and isolated from the skin of Hydrophylax bahuvistara, a species of frog found in South India, by a team of Emory University researchers.^[1] The team that discovered urumin tested the peptide against 8 different H1N1 and 4 different H3N2 viruses, as well as various other influenza viruses.^[1] The peptide specifically targets the evolutionarily conserved H1 hemagglutinin stalk region of H1-containing influenza A viruses.^[1] Additionally, urumin was active against drug-resistant influenza A viruses, that were resistant against oseltamivir, zanamivir, and peramivir.^[1]

While its mechanism of action is not fully understood, urumin seems to inhibit viral growth by physically destroying influenza A virions, and is able to protect naive mice from doses of influenza A infection as high as twice the LD₅₀.^[1] Because of its specific targeting of the hemagglutinin stalk region of the influenza A virus, the mechanism of action of urumin is similar to that of antibodies induced in the body by universal influenza vaccines.^[1] Urumin was also tested for toxicity against erythrocytes and showed a TD₅₀ of 2,450 μM and TI of 664.7, indicating a favorable toxicity profile against erythrocytes.^[1] As such, urumin may represent the basis for a potential first-line antiviral treatment against influenza A, particularly in the context of influenza outbreaks,^[1] although the discoverers of the peptide have stated that urumin is far from becoming an anti-flu drug.^[2] Urumin was named after the urumi, a sword used in Kalaripayattu, the martial art of Kerala, where urumin was discovered.^[3][1]