BIOLOGICAL PIGMENTS: PYRROLE DERIVATIVES, CAROTINOIDS, FLAVINS

摘要: This chapter focuses on biological pigments such as pyrrole derivatives, carotenoids, and flavins. Bilirubin occurs in bile a soluble sodium bilirubinate, biliary calculi, it is present an insoluble calcium salt. It can be prepared from evaporated residues or powdered gallstones. red-brown tetrapyrrole, water, dilute acids, the common fat solvents. hot chloroform alkalis, which dissolves to form salts. The solutions show no characteristic absorption spectrum. Mild oxidation converts bilirubin into green pigment, biliverdin, more powerful oxidants resolve four units. Porphyrins are widely distributed of high stability. nitrogen tetrapyrrole cluster readily combines with metals Fe, Cu, Mg, Mn, metallo-porphyrins porphyrans , having catalytic properties. Urobilinogen, colorless precursor urobilin, one normal constituents fresh urine may greatly increased amount by conditions intestinal stasis putrefaction.