38 UNITY AND DIVERSITY IN BIOCHEMISTRY 



B. Natural Phenanthrene Derivatives 



There are a number of substances occurring naturally that, from the 

 organic chemists' point of view, are related to phenanthrene. This latter 

 substance, Cx4Hio, is obtained from coal tar together with anthracene, of 

 which it is an isomer. 



Among the phenanthrene derivatives present in the biosphere, one finds 

 many quininoid pigments and a number of alkaloids such as those of the 

 morphine group. But the phenanthrene derivatives most characteristic of 

 living organisms are those in which the phenanthrene nucleus has a cyclo- 

 pentane ring fused to it. 



CH 

 HC CH 



CH C CH 



// \ / \ / 

 HC C C 



HC C CH 



\ / \ / 

 CH CH 



Phenanthrene 



If a hydrogen atom is added to each carbon of the phenanthrene ring the 

 double bonds disappear and one obtains perhydrophenanthrene. 



H2 



c 



/ \ 



H2C CH2 



I I 



Cyclopentane 



Both the structures of cyclopentane and of perhydrophenanthrene are 

 combined in cyclopentanoperhydrophenanthrene, commonly known as 

 sterane. 



