CHEMISTRY OF EPINEPHRINE 83 



successive oxidation, methylation of the nitrogen atom and 

 decarboxylation. Attempts to carry out experimentally 

 these processes have, however, not been successful. Tyrosine 

 is oxidized in the presence of tyrosinase to give 3,4, dihydroxy- 

 phenylalanine (acrostically abbreviated to dopa), which repre- 

 sents the first stage in the above described series of reactions 

 by which tyrosine would be expected to be converted into 

 epinephrine. Moreover, dopa, although never demonstrated 

 in animals, has been found in the pods of the bean (Viciafaba) 

 and in certain insects. If tyrosinase is allowed to act on the 

 methyl ether of dopa (3,4-dihydroxyphenyk/V-methylalanine) 

 a small amount of a pressor base is formed whose activity is 

 much enhanced by reduction. Heard and Raper 290 consider 

 this pressor base to be adrenalone, the ketone of epinephrine 

 (adrenaline), represented by the formula, 



COCH 2 (NHCH 3 ) 



OH 

 OH 



which on reduction gives epinephrine. The above reaction 

 occurs simultaneously with the main series of reactions which 

 give rise to indole derivatives and ultimately to melanin. 35 



Although the intermediate compounds have not been iso- 

 lated, we can, according to Heard and Raper, 35 represent the 

 probable changes occurring in the transformation of tyrosine 

 to epinephrine by the following formulae: 



CH 2 CH(NH 2 ) -COOH CH 2 CH(NH 2 )COOH 



+0 I Jqjj methylation 



OH OH 



tyrosine dopa 



