98 AARON BENDICH 



responding nucleoside. Xanthine was discovered by Marcet (1817) in 

 bladder stones.'*^ Hypoxanthine was found in beef spleen (and so named 

 by Scherer^*^ in 1850), in beef and horse meat, and in creatine mother- 

 liquors by Strecker.^^^ The distribution of hypoxanthine and xanthine (and 

 its methylated derivatives such as caffeine, theophylline, and theobromine) 

 in tea,'^^ coffee, and cocoa and as urinary constituents is ably discussed 

 else where. ^^^•'^'' A purine nucleoside, spongosine, isolated from the sponge 

 Cryptoteihia crypta (Florida) , has been shown to be a pentosylmethylamino- 

 oxypurine, the aglycone of which has been deaminated with nitrous acid to 

 a methyldioxypurine.^^^ 



The free purines and their simple derivatives have been found much more 

 frequently in nature than the pyrimidines. Of the nucleic acid pyrimidines, 

 only uracil has been found in the free form,^^ and recently hydrouracil 

 (2 , 6-dihydroxy-4 , 5-dihydropyrimidine) has been obtained . from beef 

 spleen.' ^2 a. pentofuranoside of thymine, spongothymidine, thought to be a 

 xylofuranoside, was isolated^^^'^^ from Florida Cryptoteihia sponges. The 

 identity of the sugar portion as xylose was supported by paper chromato- 

 graphic analysis, ^^^ and the point of its attachment to N-3 of the thymine 

 follows from the resistance of the glycoside towards acid hydrolysis'^' 

 and from the character of the ultraviolet absorption spectra.'^' ''^^ 



The coenzyme of the system (galactowaldenase) which catalyzes the con- 

 version of galactose- 1 -phosphate into glucose-1-phosphate'^^ has been iso- 

 lated from bakers' yeast ;'"'^* the coenzjone contains uridine, two phos- 

 phate groups, and glucose and is named uridine diphosphate glucose 

 (UDPG). Upon gentle acid hydrolysis of TJDPG, glucose and a uridine 

 diphosphate (shown by synthesis to be uridine-5 '-pyrophosphate^ ^^) were 

 obtained and the formula XXVIII was assigned ;'^^-'^^ the formula 



'** Marcet, "An Essay on the Chemical History and Medical Treatment of Calcul Dis-" 



orders," London, 1817: cited in refs. 18, 119, and 183. 

 86 J. Scherer, Ann. 73, 328 (1850). 

 " A. Strecker, Ann. 102, 204 (1857); 108, 129 (1858). 



88 A. Baginsky, Z. physiol. Chem. 8, 395 (1883-84). 



89 W. C. Rose, Physiol. Revs. 3, 544 (1923). 



^0 A. A. Christman, Physiol. Revs. 32, 303 (1952). 



9' W. Bergmann and R. J. Feeney, /. Org. Chem. 16, 981 (1951). 



«2 C. Funk, A. J. Merritt, and A. Ehrlich, Arch. Biochem. and Biophys. 35, 468 (1952). 



93 W. Bergmann and R. J. Feeney, /. Am. Chem. Soc. 72, 2809 (1950). 



9^ K. Makino and K. Satoh, Abstr. I2th Intern. Congr. Pure Appl. Chem. 1951, 317. 



95 J. J. Fox and D. Shugar, Biochim. et Biophys. Acta 9, 369 (1952). 



9«L. F. Leloir, ref. 122, p. 67. 



97 C. E. Cardini, A. C. Paladini, R. Caputto, and L. F. Leloir, Nature 165, 191 (1950). 



98 R. Caputto, L. F. Leloir, C. E. Cardini, and A. C. Paladini, /. Biol. Chem. 184, 333 

 (1950). 



'99 N. Anand, V. M. Clark, R. H. Hall, and A. R. Todd, J. Chem. Soc. 1952, 3665. 



