234 SCIENCE PROGRESS 



is not increased by the introduction of an alcoholic hydroxyl 

 nor by that of a methylamino group. When two methyl groups 

 are attached to the nitrogen (i.e. in hordenine), the pressor 

 activity is much reduced ; three methyl groups, as in hordenine 

 methiodide, HO . C 6 H 4 . CH 2 . CH 2 . N(CH 3 ) 3 I, condition an intense 

 and evanescent pressor activity, which, however, is of quite a 

 different type, resembling that of nicotine. 



The activity of />-hydroxyphenylethylamine is not much 

 increased by the introduction merely of a second phenolic 

 hydroxyl, whereby it is converted into 

 HO 



HO { y— CH 2 . CH 2 . NH 2 (3 : 4-dihydroxyphenylethylamine) 



but nevertheless the second phenolic hydroxyl prepares the 

 way, as it were, for further increase in activity, inasmuch as 

 this is greatly increased whether a methyl group be introduced so 

 as to form the secondary base (OH) 2 .C 6 H 3 .CH 2 .CH 2 .NH.CH 3 

 or an alcoholic hydroxyl group so as to form the compound 

 (OH) 2 . C 6 H 3 . CH(OH) . CH 2 . NH 2 ; if both hydroxyl and methyl 

 be introduced adrenaline is produced. 



HlSTIDINE AND THE AMINE DERIVED FROM IT 



With the exception of the benzenoid amino-acids, of proline 

 and of oxyproline, histidine is the only amino-acid showing 

 cyclic structure ; it contains a glyoxaline ring, which is also 

 present in the alkaloid pilocarpine. When the carboxyl group 

 of histidine is removed, the base that is formed, unlike its parent 

 substance, has great physiological activity and approaches more 

 nearly to the most toxic vegetable alkaloids than does any 

 other amine of its class. This base is : 



$-Iminazolylethylamine (4-/3-Aminoethylglyoxaline). — Like 

 /-hydroxyphenylethylamine, it was obtained synthetically 

 before its occurrence as a product of putrefaction had been 

 observed. In preparing it, Windaus and Vogt (Ber. 1907, 

 40, 3695) started from iminazolylpropionic acid, which had 

 been obtained previously from histidine and also prepared 

 synthetically; this acid was converted first into a hydrazide, 

 then into a urethane and finally, by hydrolysis, into the base 



CH = N\ CH = N\ 



I >C.CH 2 .CH 2 .COOH -> I >C.CH 2 .CH 2 .NH 2 



NH.CH^ NH.CH^ 



^-Iminazolylpropionic acid /3-Iminazolylethylatnine 



