INOSITOL 



5. L. Young, Biochem. J., 1934, 28, 1428, 1435. 



6. R. A. Gregory, ibid., 1935, 29, 2798. 



7. B. S. Piatt and G. E. Glock, ibid., 1943, 37, 709. 



8. D. W. WooUey, /. Biol. Chem., 1941, 140, 453 ; /. Exp. Med., 



1942, 75, 277, 



9. R. J. Williams, A. K. Stout, H. K. Mitchell and J. R. McMahan. 



Univ. Texas Publ., 1941, No. 4137, 27. 



10. V. Jurist and J. R. Foy, /. Bad., 1944, 47, 434. 



11. L. Atkin, A. S. Schultz, W. L. Williams and C. N. Frey, Ind. Eng. 



Chem., AnaL Ed., 1943, 15, 141. 



12. G. W. Beadle, /. Biol. Chem., 1944, 156, 683. 



13. P. R. Burkholder, I. McVeigh and D. Moyer, /. Bact., 1944, 48, 



385. 



14. W. B. Emery, N. McLeod and F. A. Robinson, Biochem. J., 1946, 



40, 426. 



6. OCCURRENCE OF INOSITOL 



Inositol occurs in most animal and plant tissues, fruits and cereal 

 grains being especially good sources. Yeasts and certain other 

 micro-organisms contain relatively large amounts,^ and this is reflected 

 in the relatively enormous amounts of inositol present in yeast extracts 

 in comparison with their contents of other members of the vitamin B 

 complex. 2 Thus, whereas the amounts of aneurine and pantothenic 

 acid present in three different yeast extracts were of the order of 100 

 fjig. per g., the amount of inositol present varied between 1000 and 

 3000 fjLg. per g. Relatively large amounts (2000 to 3000 i^g. per g.) 

 were also present in crude liver extracts. 



Inositol was shown ^ to be present in liver in a water-soluble, 

 alcohol-insoluble, non-dialysable form, presumably in combination 

 with a protein. It was also shown to be present in the form of a 

 complex in heart muscle,^' ^ and was isolated from thyroid ^ and from 

 kidneys, spleen and testes.' All the inositol present in brain cephalin 

 was in the form of a phosphatide, diphosphoinositide.*^* 



In plants, inositol occurs in the form of its phosphoric esters. 

 Inositol monophosphoric ester and triphosphoric ester have been 

 shown to exist in wheat bran,® but the commonest inositol compound 

 in cereals is the hexaphosphoric ester, phytic acid. The mixed cal- 

 ciimi magnesium hydrogen salt of this acid, known as phytin, occurs 

 in a large variety of plant materials, particularly cereals. Phytic 

 acid forms a very stable calcium salt, in which neither the calcium 

 nor the phosphorus can be utilised. Thus the phytic acid in oats 

 renders non-available the whole of the calcium present in the cereal 

 and, what is worse, immobilises much of the calcium present in other 

 constituents of the diet, such as milk.® The phytic acid present 



570 



