Structure of Pigments of the Red Sweat of the Hippopotamus

Your notion of the structure of hipposudoric and norhipposudoric acids, pigments of the red sweat of the hippopotamus, may need some updating. This newly published study calls for your attention:

Refined Structure of Hipposudoric and Norhipposudoric Acids, Pigments of the Red Sweat of the Hippopotamus,” Takatoshi Matsumoto, Yoko Saikawa, Masaya Nakata, and Kimiko Hashimoto, Chemistry Letters, epub 2015. (Thanks to T Brian H McMurry for bringing this to our attention.) The authors are at Keio University, Japan.

BONUS: Video of one way to collect sweat from a hippo: