Papilioerythrinone: A new ketocarotenoid in integuments of orange pupae of a swallowtail, Papilio xuthus, and carapaces of a crab, Paralithodes brevipes (hanasakigani in Japanese).

A minor carotenoid in integuments of orange pupae of a swallowtail, Papilio xuthus, was found also in carapaces of a crab, Paralithodes brevipes (hanasakigani). This new carotenoid showed a visible absorption spectrum similar to that of papilioerythrin (=α-doradexanthin) and was named papilioerythrinone. Reduction of this compound with sodium borohydride occurred in 2 steps and gave products identical with the reduction products of papilioerythrin. Therefore, the structure 3-hydroxy-β, ε-carotene-4, 3'-dione (IV) is ascribed to papilioerythrinone.