288 



COOH 



H2N— CH 

 I 



I 



,^^-^ 



COOH 

 I 



H2N— CH 

 I 

 CH, 



HORMONES 



COOH 

 I 

 H.,N— CH 



i 

 CH, 



NH2 



CH2 

 I 

 CH2 



I 

 C. 



C C 



HC=^ XH (ox) HC^ ""CH (ox) HC^ ^CH — CO2 HC^^^CH 



II * I II * I II * I II 



HC^ XH HC=:, C-OH HC^ C-OH 



c c c 



HC 



•^^,^CH 



C 

 H 



L-Phenylalanine 



OH 

 L-Tyrosine 



OH 

 L-Dihydroxy- 

 IDhenylalaninc 



OH 

 Hydroxytyramine 



(ox) 



NH2 

 I 

 CH2 



I 

 HOCH 

 I 



HC^ ""CH 



HC^ ^C— OH 

 C 



I 

 OH 



^Norepinephrine 



metliylation 



HNCH3 



CH2 

 I 



HOCH 

 I 



HC=^ CH 



I II 



HC^ ,/C— OH 



I 

 OH 



i-Epinepiirine 



It has been demonstrated that slices of the adrenal medulla convert hy- 

 droxytyramine in vitro into a substance with the biological properties 

 of epinephrine and that norepinephrine is methylated in vivo according 

 to the reaction shown. Furthermore, Gurin and Delluva injected into 

 rats D L-phenylalanine labeled with C^'* (radioactive) in the —COOH 

 group and (or) in the alpha position (carbon atom next to the — COOH). 

 They showed that radioactive epinephrine with all of its C^"^ located 

 in the terminal carbon of the side chain was formed. This is good evi- 

 dence that epinephrine is actually made from phenylalanine by the 

 living animal. There is no direct proof that dihydroxyphenylalanine 

 takes part in the biosynthesis, but some such dihydroxy substance must 

 obviously be involved at some stage of the process. 



Both hormones contain an asymmetric carbon atom and are therefore 

 optically active. The levorotatory or i-forms are the naturally occurring 

 isomers and are about fifteen times more effective than the corresponding 

 c?-forms. Both isomers of each hormone have been prepared by chemical 

 synthesis, and the pure Z-forms have been isolated from the adrenals 

 of various animals. 



Injection of epinephrine is followed by a rapid rise of blood pressure 



