160 



BIOCHEMICAL SYSTEMATICS 



H2C 



OCH3 

 OCH3 

 hydrastine 



(g) Bisbenzylisoquinoline derivatives. These alkaloids consist 

 of two benzylisoquinoline groups joined by one or more ether linkages. 

 Thev' are found in several families including the Magnoliaceae and 

 Berheridaceae, 



H3CN. 



magnoline 



INDOLE ALKALOIDS 



This class is probably far more heterogeneous than the two 

 previous classes. Although other mechanisms of formation of the 

 indole nucleus doubtlessly exist, in some cases at least indole is 

 derived from tryptophane metabolism which, in turn, is derived as an 

 early offshoot from the pathway to the aromatic amino acids. 

 Shikimic acid is a parent substance for both groups, and at least in 

 the early stages of their formation all alkaloids discussed so far are 

 likely to have metabolic connections with each other. Some simple 

 indole alkaloids are known (for example, gramine, illustrated below), 

 and it is not surprising to find that they too occur in a number 

 of widely separated families. 



.CHa 



-CH2N 



/ 



CH, 



gramme 



