202 BIOCHEMICAL SYSTEMATICS 



they also possess the rare ortho-hydroxy substitution of the B-ring 

 (Dave etal, 1962). 



H3CO 



H3CO 



artocarpin isoartocarpin 



The isoprenoid side chains which distinguish the two compounds 

 are hnked differently, that is, C-C in artocarpin and 0-C in isoarto- 

 carpin. Yet, spatially the ortho-OH of the B-ring is close to the 3 

 position at which the isoprene substitution in artocarpin occurs. 



Flavonoids are of special interest in that they represent a 

 molecular composite formed via several basic pathways each of which 

 leads to other secondary compounds: the shikimic acid pathway, 

 mevalonic acid pathway, and acetate condensation. Other examples of 

 phenolic-isoprenoid derivatives are known, including other flavonoids, 

 rotenoids, coumarins, and quinones (Ollis and Sutherland, 1961). 



When all the known derivatives of the classes of flavonoids 

 including glycosides, are totaled, they number into the hundreds. 

 Geissman and Hinreiner (1952) listed almost 200 different flavonoids 

 already known to occur in nature, and many new types have since 

 been described (for a recent comprehensive list see Geissman, 1962). 



Genetic studies concerning the 

 flavonoid compounds 



As noted previously the inheritance of certain flavonoid pig- 

 ments has been studied more intensively than perhaps any other group 

 of chemical substances in flowering plants (Alston, 1963). The antho- 

 cyanins, particularly, have been the objects of numerous investigations 

 extending back almost to the nineteenth century. Onslow (1916) called 

 attention to the possibility of biochemical genetic studies of anthocy- 

 anins shortly after Willstatter had established their chemical nature. 

 Apparently the first actual biochemical genetic investigation was that 

 of Scott-Moncrieff (1931) who showed that in Pelargonium zonale a 

 dominant gene, producing a rose-pink flower, governed the formation 

 of a cyanidin glycoside. The double recessive, in contrast, contained a 

 pelargonidin glycoside and was salmon-pink in color. 



By 1936 a number of biochemical-genetic studies of flower 



