148 



TERPENOIDS AND STEROIDS 



tomatidine (Solanum spp. ) 



Modified steroid: 



veratramine (Veratrum spp. ) 



TETRA TERPENOIDS 



The most familiar tetraterpenoids are the carotenoids — yellow to red, fat soluble 

 pigments occurring throughout the plant kingdom and in many different types of tissues. 

 About 80 of them are known. Hydrocarbon pigments are called carotenes and oxygenated 

 derivatives are xanthophylls. Colorless tetraterpenoids are also known (e. g. phytoene, 

 phytofluene) but have been studied much less than the carotenoids. Structurally the only 

 difference between colored and colorless tetraterpenoids is the larger number of conju- 



gated double bonds found in the former, 

 ring systems. They are either acyclic, 

 be depicted by the following skeleton: 



The tetraterpenoids never contain large condensed 

 monocyclic, or bicyclic. Acyclic members may 



c 

 I 







15 



.A 



C4 sC V'V "c'"V, 



10 



la 



1+ 



I5-' 



14' 12' 



c.i3'a 



C3 



\/ 



c— c 



i 



ir 



10' 8' 



^ c V I 

 c x/' 



6' ''X 



3'c 



