V. si'i;(ii'i( 11^ OF A('ri(»N 145 



A. 1:1:1. ATiox OK XA\rii()Pri:inx to poa 



The role ol' xanthopterin in nutrition is an enigma in the P(1A problem. 

 From the beginning, xanthopterin has crossed and recrossed the trail, some- 

 times guiding, sometimes serving only to confuse those intent on learning 

 the nature and function of PCiA. This yellow pigment, one of a class of com- 

 pounds found in the wings of butterflies, has a structure closely related to 

 the pteridine portion of PGA. 



X 



OH OH 



OH 



N 



Xanthopterin Leucopterin 



Although our knowledge of xanthopterin originated in 1891 when Hop- 

 kins began his investigations on the wing pigments of the English brim- 

 stone butterfly,'-^ it was not until 1941 that Wieland and his collaborators 

 completed the degradation work with xanthopterin and leucopterin, and 

 Purrman-" finally accomplished their synthesis. The problem of obtaining 

 sufficient material for chemical degradation studies was an acute one, and 

 altogether over 1,000,900 butterflies of various tN^^es were used by differ- 

 ent workers in this field. -^ 



Xanthopterin has also been isolated from human and animal urine and 

 designated uropterin by Koschara.'^- ^^ It occurs in insects other than the 

 lepidoptera; it has been detected in the crab but apparently not in plants.-^ 



Rominger et al.^^ found that rats 3 to 4 weeks old developed macrocytic 

 anemia when fed exclusively on goat's milk. The erythrocyte count fell to 

 around 1 million, and the animals did not respond to sujiplementation with 

 iron. Typical reticulocyte responses wei'e oi)tained with liver preparations. ^- 

 Tschesche and Wolf^^ found that injection of uropterin (xanthopterin) ob- 

 tained from Koschara produced a rise in the erythrocyte count. A daily 

 dose of 1.0 7 produced an elevation of 2 to 3 million in the erythrocyte 

 count in 14 days. Ten micrograms produced no greater response than 1.0 



" F. G. Hopkins, Nature 45, 197 (1891), cited by M. Gates, Chem. Revs. 41, 63 (1947). 



" R. Purrman, Ann. 548, 284 (1941). 



"M. Gates, Chein. Revs. 41, 63 (1947). 



" W. Koschara, Z. phijsiol. Chem. 240, 127 (1936). 



3»W. Koschara, Z. phuHiol. Chem. 277, 159 (1943). 



" E. Rominger, H. Meyer, and C. Bomskov, Z. (jes. exptl. Med. 89, 786 (1933). 



32 E. Rominger and C. Homskov, Z. ges. exptl. Meet. 89, 818 (1933). 



" R. Tschesche and H. J. Wolf, Z. phi/siol. Chem. 244, I, (1936). 



