ADRENALINE (EPINEPHRIN, ADRENINE) 89 



nucleus (in Abel's epinephrine). The constitution of the " alkaloidal " 

 substance formed by the action of acids on adrenaline has not been 

 elucidated, nor of the base C 3 H 4 ON a obtained by Abel [1904] on 

 oxidising adrenaline with nitric acid. Adrenaline is readily attacked 

 by various oxidases [Neuberg, 1908; Abderhalden and Guggenheim, 

 1908]. 



Colour Reactions of Adrenaline. 



The principal colour reactions were already observed by Vulpian 

 and have more recently been used for the estimation of adrenaline. 

 A general review of the various quantitative colorimetric methods has 

 lately been furnished by Borberg [1912], The reactions are as 

 follows : 



I. Ferric chloride produces in neutral or slightly acid solution a 

 grass green coloration, changing to violet, reddish violet, and red on 

 the careful addition of dilute alkali. This is a reaction characteristic 

 of catechol derivatives. The green coloration is the more fugitive and 

 the less strongly marked, the more acidic the solution is. The limit of 

 sensitiveness is about I : 30000, but the addition of sulphanilic acid 

 increases the sensitiveness tenfold and changes the green colour to 

 reddish brown or brown yellow (Bayer [1909]). Falta and Ivcovic 

 [1909] describe another sensitive modification of the ferric chloride 

 reaction. For the detection of adrenaline in urine Borberg [1912] 

 gives the limit for the green ferric chloride reaction as I : 100,000. 

 On standing a red coloration is produced up to I : 300,000. 



II. A pink or rose red coloration (" tout a fait remarquable," 

 Vulpian) is produced in adrenaline solutions on prolonged exposure 

 to air and, almost immediately, by various oxidising agents. The 

 change of colour is less rapid in faintly acid solution than in neutral 

 solution, and more rapid in alkaline solution. It is also brought 

 about by oxidases ; from the behaviour of adrenaline to tyrosinase, 

 Gessard [1904] first deduced a relationship to tyrosine. Neuberg 

 [1908] found that an enzyme from the ink-bag of Sepia officinalis 

 produces a black pigment from adrenaline, and Abderhalden and 

 Guggenheim [1908] observed that adrenaline solutions are coloured 

 red by a tyrosinase from the fungus Russula delica ; the laevo- , the 

 dextro- , and the racemic forms are all coloured at the same rate. The 

 formation of pigments from adrenaline has been considered by some to 

 be connected with the pigmentation of the skin in Addison's disease. 



The oxidising agents employed for the red colour reaction for 

 adrenaline are : 



