Isolation of Biliverdin Ixa, as Its Dimethyl Ester, from Emu Eggshells

A laboratory experiment is described that extracts the tetrapyrrolic teal-colored biliverdin IXa, as its dimethyl ester, from commercially available emu eggshells. The extraction of ~10 mg samples of biliverdin is simple and requires two 3 h lab periods: A two-step acid digestion and liquid-liquid extraction, followed by short silica gel flash column chromatography. The deeply colored extract can be characterized by TLC, UV-vis, IR, [superscript 1]H NMR spectroscopy, ESI+ mass spectrometry, or its diagnostic chemical reduction to the yellow derivative bilirubin. A small-scale variant of this extraction requires only a single 3 h lab period, and the extracts can be analyzed by UV-vis spectroscopy, ESI[superscript +] MS, or HPLC. An introduction to the biological origin of biliverdin is provided. This pedagogically flexible project combines natural product isolation with the spectroscopic characterization of a multifunctional biomedically important compound and touches upon many aspects of chemistry and biology. The colorful experiment is appropriate for the introductory organic chemistry laboratory and possesses the prerequisites for a chemistry-biology interlaboratory approach.