Uteroverdin

Abstract

ONE of us¹ has recently isolated oocyan—the blue-green pigment of the shells of many birds' eggs—and characterised it as an ether-soluble pyrrol pigment closely related to the bile pigments. We have now found a second example of this class of substances in the green pigment of the dog's placenta, the properties of which are very similar to those of oocyan. This pigment was examined in 1871 by Etti,² and considered to be biliverdin ; it is formed by the transformation of the blood-pigment in the extravasates of the dog's placenta.³ While the methoxyl content of the ester of oocyan indicated a molecule with only three pyrrol nuclei, the analysis and methoxyl content of the methyl ester of uteroverdin (as we will call the substance) show that we are dealing with a substance with four pyrrol nuclei. From its composition (C₃₅H₃₈–₄₂N₄O₆) it appears that it is the dimethyl ester of a dehydrobilirubin or dehydromesobilirubin. The values for C, H, and N (not, however, the methoxyl content) of the ester of oocyan agree also with the formula C₃₇,H₄₂N₄O₈ ; that is to say, with that of the trimethyl ester of a substance which differs from uteroverdin only in possessing one more carboxyl group. A further investigation of oocyan by one of us (R. L.) is in progress.