152 



IV. BILE PIGMENTS 



{1213, p. 249)* assumed that this reaction was due to a tryptophane deriva- 

 tive present in these urines. By coupling with diazotized dichloroaniline, 

 Sachs, however (2410,2411), obtained a crystalHne azo dye C31H24O7N6CI4. 

 The chlorine content shows that two molecules of the diazonium compound 

 have coupled with one molecule of the chromogen. The chromogen thus has 

 the composition C19H20O7N2. This can hardly be brought into harmony with 

 the assumption of a tryptophane derivative, but agrees with a structure of 

 a dipyrrylmethane containing acetic acid and propionic acid side chains of 

 the structure shown in Figure 30. Such a compound would condense with 



AC P AC P 



H 



c N 



H 



(C.cHjoOsNj) 



Fig. 30. Possible formula for the urinary chromogen reacting with 

 diazobenzenesulfonic acid. 



two moles of diazonium reagent in the two free a-positions and would be 

 identical with, or closely related to, porphobilinogen. Waldenstrom reported 

 that porphobilinogen coupled with the diazo reagent {2911). 



Decisive evidence for the occurrence of such dipyrrolic compounds with 

 uro side chains would be of great importance for the problem of porphyrin 

 synthesis in the body (c/. Chapter XIII). 



8.4. Bacterial Pigments 



We may mention here two interesting bacterial pigments. Prodigiosin, 

 the red pigment oiSerratia marcescens {Bacillus prodigiosus)\s a pyrrylpyrro- 

 methene of the structure shown in Figure 31. Its structure was proved by 



Am 



Fig. 31. Prodigiosin (.\m = amy]). 



Wrede and collaborators {3122-3124) and by Raudnitz {2214). It has 

 absorption bands at 573.5 and 501 m/x {650). 



* In Heilmeyer's book {1213), Figures 112 and 113 have evidently been inter- 

 changed. Figure 113 giving the absorption curve of the azo dye. 



