12 



PHYSIOLOGY OF NUTRITION 



hematoporphyrin, which was obtained by Nentskii and Sieber from hemoglobin 

 of animal blood. Hematoporphyrin has the composition Ci 6 Hi 8 N 2 0i, the dif- 

 ference between it and phylloporphyrin, as represented by these formulas, con- 

 sisting in the lower oxygen content of the latter. 1 The method used in the 

 isolation of hematoporphyrin is also analogous to that employed for phyllopor- 

 phyrin. The spectra of these two substances, in various solvents, 2 are almost 

 identical, except that the absorption bands of hematoporphyrin sometimes 

 appear slightly displaced toward the red (Fig. 7). 



Both hematoporphyrin and phylloporphyrin, when heated in a test-tube, 

 form a vapor which gives a red color to pine sawdust moistened with hydro- 

 chloric acid, a characteristic indication of the presence of the pyrrol ring 

 (C4H5N): the characteristic odor of pyrrol may also be plainly recognized in 

 this vapor. 3 It thus appears that chlorophyll (acting synthetically) and hemo- 

 globin (acting analytically) are closely related, in that the pyrrol ring is common 

 to both. It is of great interest also to note that the bile pigment bilirubin 

 has the same percentage formula as hematoporphyrin (Ci6Hi 8 N 2 0,j). Further- 

 more, Nentskii and Zaliesskii 4 succeeded in obtaining mesoporphyrin ivom hemin, 

 the latter substance being formed by the action of acids upon hemoglobin. 

 Mesoporphyrin has the composition Ci 6 Hi 8 N 2 2 , and stands between hemato- 

 porphyrin and phylloporphyrin in oxygen content. By a further decomposition 

 of hemin these authors obtained hemopyrrol (Ci3H 8 N), a volatile oil that turns 

 red in air and changes into urobilin, which is also obtained from bilirubin. 

 When Nentskii and Marchlewski 5 succeeded in obtaining hemopyrrol and 

 urobilin from phylloporphyrin, the relationship between chlorophyll and 

 hemoglobin was conclusively established. The atomic group common to 

 both, as in the case of the bile pigments, occurs in hemopyrrol. The following 

 diagram represents the relationship existing between these three groups of 

 substances. 



Chlorophyll Hemoglobin 



Hematoporphyrin 



Phylloporphyrin 



Hemopyrrol 



! 



Urobilin 



Bilirubin 



1 For the difference in structure between the two compounds see: Willstatter, Richard, and Asahina, 

 Yasuhiko, Oxydation der Chlorophyllderivate. Liebig's Ann. Chem. u. Pharm. 373 : 227-238. 1910. 



2 Schunck, E., and Marchlewski, L., Zur Chemie des Chlorophylls. (Vierte Abhandlung.) Liebig's 

 Ann. Chem. u. Pharm. 290: 306-313. 1896. 



3 Schunck, E., and Marchlewski, L., Zur Chemie des Chlorophylls. (Dritte Abhandlung.) Liebig's 

 Ann. Chem. u. Pharm. 288: 200-218. 1895. 



4 Nencki, M., and Zaleski, J. Ueber die Reduclionsproducte des Hamins durch Jodwasserstoff and 

 Phosphoniumjodid und iiber die Constitution des Hamins and seiner Derivate. Ber. Deutsch. Chem. Ges. 

 34 1 ' 997-IOIO. 1901. 



6 Nencki, M., and Marchlewski, L., Zur Chemie des Chlorophylls. Abbau des Pyhllocyanins zum 

 Hamopyrrol. Ber. Deutsch. Chem. Ges. 34"; 1687-1693. 1901. 



