Studies on Bile Pigments III. Biliverdins Derived From Natural Bilirubins

1. Absorption maxima of hydrochloric biliverdins derived from the natural indirect bilirubin existed at 680 mμ and 375 mμ, but the maxima of biliverdins purified on the column of silica gel existed at 640 mμ and 390 mμ. 2. The natural salt-form bilirubin was oxidized by hydrochloric acid to biliverdin, of which absorption maxima existed at 685 mμ and 370 mμ in a methanolic solution as well as in 5% hydrochloric methanol, but the purified biliverdin in chloroform solution showed the maxima at 640 mμ and 390 mμ. 3. The natural ester-form bilirubin could be transformed into biliverdin by oxidation of its alcoholic solution in the presence of hydrochloric acid. The crude biliverdin had absorption maxima at 645 to 655 mμ, 600 mμ and 320 mμ, and the crude hydrochloric biliverdin had the maxima at 665 to 675 mμ, 620 mμ and in the near ultra-violet range, while the purified biliverdin in chloroform solution had the maxima at 640 mμ and 380 mμ. 4. The biliverdins derived from the indirect, salt-form and ester-form bilirubin had quite similar absorption maxima after purifications by adsorption chromatography.