4:04 CHEMISTRY OF THE LEUCOMAINS. 



Theophyllin or l-S-di-methyl xanthin (p. 339), C^HgNp, , was 



isolated in 1888 by Kossel' from the alcoholic extract of tea leaves. 

 It has not been met with as a product of nuclein metabolism in the 

 body nor even as a cleavage product. According to Albanesi a di- 

 methyl xanthin, presumably theophyllin, was present in his urine 

 after taking caffein. This, however, has been doubted by Kriiger.' 

 Nevertheless, that theophyllin may be present in the urine is shown 

 from Kriiger's own experiments with caffein on dogs (p. 406). 

 When large doses were administered all three di-methyl xanthins 

 were present in the urine and of these theophyllin was the most 

 abundant. It would seem therefore that in the dog, at least, caffein 

 undergoes cleavage, yielding as the chief di-methyl xanthin, theo- 

 phyllin, and on further cleavage this yields 3-methyl xanthin. In 

 other words the methyl group in position 7 is the first to be split off 

 and that in position 1 follows next. The large amounts of 1- and 

 7-methyl xanthins in the urine of man would indicate that in the 

 human body the cleavage is different in kind from that in the dog 

 and is more nearly like that in rabbits. 



Theophyllin was the first xanthin derivative synthesized by 

 Fischer and Ach.* 1.3-di-methyl uric acid with phosphorus oxy- 

 chlorid yields chlor-theophyllin which on reduction yields the base 

 (p. 337). Traube * prepared theophyllin as well as the above uric 

 acid out of di-methyl urea and cyanacetic acid. With methyl iodid 

 it yields caffein. 



In tea extract the base is associated with caffein, xanthin, adenin 

 and hypoxanthin. Further investigations are necessary to determine 

 whether the other di-methyl xanthins and the mono-methyl xanthins 

 are present in the extract. The origin of these xanthin derivatives 

 in the tea-plant is likewise involved in obscurity. They may be 

 regarded as direct synthetic products or as cleavage forms from 

 nuclein. 



Inasmuch as theophyllin cannot be regarded as a product of tissue 

 metabolism a detailed description of its properties in this connection 

 is unnecessary. The reader is therefore referred to Kossel's original 

 paper. 



Theobromin or 3-7-di-methyl xanthin (p. 336), C^HgNp^, was 

 isolated from cocoa in 1842 by Woskresensky, but its structure was 

 not determined until 1883. It has been found only once in urine, 

 and then in the case of a dog after administration of caffein in large 

 doses (p. 406). The amount of theobromin was about the same 

 as that of paraxanthin and was much less than that of theophyllin. 



> Zeits. phygiol. Gliem., 13, 298. 

 ' Berichte, 32, 2819, 2280. 

 'Berkhte, 28,3135. 

 * JBerichte, 33, 3052. 



