Metabolism of Inositol 



189 



Replacement of this equatorial hydroxyl by a polar hydroxyl (VIb) ,* 

 by oxygen (XI) or by hydrogen (XIX) prevents enzymatic oxidation; 

 col-responding changes in position b are without effect. 



Not oxidized 



VI b* 



XI 



XIX 



Oxidized 



VI a* 



XVII 



XX 



The validity of this generalization was confirmed and its scope ex- 

 tended by considering the other cyclitols that had been studied. Myo- 

 inositol (XI) has five equatorial hydroxyls. The replacement of the 

 equatorial hydroxyl in position a by a polar hydroxyl group (IV), by 

 hydrogen (XXI), or by oxygen (XIV) does not interfere with the 

 oxidation of the north polar hydroxyl group. 



Oxidized 



IV 



XIV 



Similarly, oxidation of the polar hydroxyl group occurs when the 

 equatorial hydroxyl in position e is replaced by a polar hydroxyl (V) 

 or by hydrogen (XXII). 



Oxidi 



v XXII 



The importance of the equatorial hydroxyl group in position c could 

 at that time not be ascertained, as no compound without an equatorial 



* The structures are so arranged as to place the polar hydroxyl group under 

 comparison at the top of the hexagon. For this reason epi-inositol (VI) is shown 

 in two arrangements (Via and VIb). 



