Bile pigments synthesis

Halogenated pyrroles can serve as the aryl halide in Stille couplings with organotin reagents. Scott has used this idea to prepare a series of 3-vinylpyrroles, which are important building blocks for the synthesis of vinyl-porphyrins, bile pigments, and indoles [77]. Although 3-chloro-and 3-bromopyrroles fail completely or fared poorly in this chemistry, 3-iodopyrroles 101 work extremely well to yield 3-vinylpyrroles 102. 

Admitting that endogenous synthesis in the control mixtures is negligible or can be adequately suppressed, the difference in response of test and control samples toward the final detection system (Section 4) should be such that it is exclusively due to the bile pigment conjugate synthesized in the test incubation mixture. The latter requirement depends, to some extent, on the final assay procedure adopted (Section 4). 

The reaction of DMAD with the pyrrolinone 332 has been used202 for the synthesis of vinylpyrrolinones (333), which are useful for the preparation of bile pigments the isoindole 324 was also obtained. 

R. Virchow described Hamatoidin and the extra-hepatic synthesis of bile pigments from haematoidin in old haematomas (s. Galenos blood turns to bile ). 

Enzymatic activity 2. Synthesis capacity 3. Excretion capacity GPT, y-GT — ChE, — Quick s value AP, bile pigments — in the urine GOT, GDH — albumin — bilirubin, LAP — LDH ammonia, galactose EC bile acids, iron, copper, cholesterol, indocyanine green, LPX... 

Synthesis of these substances is carefully controlled, because it is metabolically expensive in terms of both energy and precursor molecules. Many, but not all, purines and pyrimidines can be interconverted. The catabolism of purines and hemes produces unique products, whereas pyrimidine catabolism produces common products. The catabolism of purines produces uric acid, which in excess can produce gout. The catabolism of hemes produces bile pigments which, when in excess in the circulation, are referred to as jaundice, and when excreted normally, add pigmentation to the feces. 

In our earlier article we reviewed the main methods then available for the synthesis of naturally occurring porphyrins and bile pigments, and the structurally and biosynthetically related vitamin (cobalamin). The review essentially covered material published up to the middle of 1971. In the present article we describe new developments during the subsequent nine years. In order to preserve continuity with the earlier article and for ease of cross-referencing we have used a similar format and order of topics. 

Progress in the synthesis of chlorophylls and bacteriochlorophylls (di- and tetra-hydro porphyrins) has been relatively slow, but the recent isolation of new reduced porphyrins, such as the physiologically active marine pigment bonellin" and sirohydrochlorin (an intermediate in vitamin B12 biosynthesis) is likely to stimulate attempts to synthesize these compounds directly from partially reduced open chain precursors rather than by reduction of preformed porphyrins (see Section 11). Considerable progress has already been made in the development of new methods for synthesizing the partially reduced bile pigments (Section 9). 

For the systematic synthesis of naturally occurring bile pigments, the most versatile method is still the stepwise coupling of pyrrole—or partially reduced analogs— to form dipyrrolic units, cf. which can be coupled together. C-labeled bilirubin IXa (40), for example, has now been synthesized by condensation of an a-unsubstituted oxopyrromethene (38) with an oxopyrromethene Mannich base (39) the label was incorporated in the dimethylaminomethyl res-... 

Total synthesis of several of the reduced bile pigments have been described during the past few years, including phycocyanobilin (41),"° mesobilirhodin... 

An interesting stereoselective synthesis of two new bile pigments" (phy-coerythrobilins) utilized the coupling of the optically active formyl oxopyrromethene (52) with the racemic oxopyrromethene (53) under acidic conditions the mixture of diastereoisomeric reaction products was separated chromatograph-... 

J. P. Weller and A. G. Gossauer, Synthesis of bile pigments X Synthesis and photoisomerisation... 

A. Gossamer, R. P. Hinze, and R. Kutschan, Syntheses of bile pigments XI Total synthesis and elucidation of the relative configuration of two epimeric methanol adducts of phycocyanobilin dimethyl ester, Chem. Ber., 114, 132 (1981). 

---