A-a-hydroxymesobiliverdin, a New Bile Pigment

In a previous paper [1] we discussed biliverdin IXa as an intermediate of phycocyanobilin biosynthesis (also compare [2—4]). The experiments involved the incubation of red algae of the species Cyanidium caldarium III-D-2 with the tetrapyrrole precursor 5-aminolevulinic acid. After 2—3 days incubation we observed as a main product a rather polar blue pigment of an as yet unknown structure in the medium as well as in the cells themselves, together with porphyrins, phycocyanobilin [5] and biliverdin IXa [1]. In this paper, the structure of the new polar blue pigment is given and its mode of formation is discussed.