THE STATUS OF BLUE-GREEN BILE-PIGMENTS OF BUTTERFLIES, AND THEIR PHOTOTRANSFORMATIONS

Blue-green bile pigments, which are found in adults of larvae of many species of butterfly, are reviewed. In contrast to the presence of biliverdin IX a 1 in some insect species, many Lepidoptera contain pterobilin 2 (biliverdin IX .gamma.), phorcabilin 3 and sarpedobilin 4, derived from 2 by cyclization. Pigments 3 and 4 are members of a new natural family of heterocyclic systems which can also be obtained in vitro from 2 by irradiation under visible light. Available information about the chemistry and biochemistry of these pigments is presented, together with a discussion about the possible biological significance of their photosensitivity.