TERPENOIDS AND STEROIDS 



139 



TABLE 10. 



Specific Rotation 



greater than -90° 

 -70° to -50° 

 -45° to -30° 

 -25° to +10° 



+10° to +30° 

 +40° to +50° 



greater than +50° 



Structural Type 



conjugated double bonds in ring B 



double bonds at 5, 6 and 22, 23 



double bond at 5, 6 



double bond at 7, 8 and possibly 

 22, 23 also 



completely saturated ring system 



double bond at 8, 9 and possibly in 

 side chain also 



not a sterol 



Example 



ergosterol 

 stigmasterol 

 /3-sitosterol 

 a-spinasterol 



stigmas tanol 

 zymosterol 



lanosterol 



Sterols of the zymosterol type are known in the fungi but have not been established yet in 

 any higher plants. The stigmasterol type is most characteristic of higher plants. Struc- 

 tures and occurrence of some plant steroids are shown below. A thorough survey of plant 

 sterols is given by Bergmann (20). 



stigmasterol (Glycine max) 



i3-sitosterol (Pinus spp.y) 



