A secretion of the hippopotamus protects its skin from the sun and bacteria thanks to two pigments that absorb UV light and have antibiotic properties.


Journal article
Octreotide acetate enables the administration of chemoradiotherapy, including the oral anticancer drug S-1, in gastric cancer patients with malignant gastrointestinal obstructionOncology LettersApril 6, 2010

“The efficient sunscreen activity of NH and HP stems from their broad absorption in the UVA and UVB regions of the spectrum.” (Galasso and Pichierri 2009:2543)

Journal article
Probing the Molecular and Electronic Structure of Norhipposudoric and Hipposudoric Acids from the Red Sweat of Hippopotamus amphibius : A DFT InvestigationJ. Phys. Chem. AMay 23, 2017
Vinicio Galasso, Fabio Pichierri

“Although the fluid secreted by the hippopotamus (Hippopotamus amphibius) is not strictly sweat as it is produced by the subdermal glands, it acts like sweat in helping to control body temperature. It is also thought to be antiseptic…What is the function of these pigments as far as the hippopotamus is concerned? Their spectra in the ultraviolet/visible range (200–600 nm; see supplementary information) indicate that they may act as sunscreens. The red pigment 2 also has antibiotic activity: at concentrations lower than that found on the hippopotamus’s skin, it inhibits the growth of the pathogenic bacteria Pseudomonas aeruginosa A3 and Klebsiella pneumonia.” (Saikawa et al. 2004:363)

Journal article
Pigment chemistry: The red sweat of the hippopotamusNatureMay 23, 2017
Yoko Saikawa, Kimiko Hashimoto, Masaya Nakata, Masato Yoshihara, Kiyoshi Nagai, Motoyasu Ida, Teruyuki Komiya

Living System/s

Hippopotamus amphibiusSpecies