BIOLOGICAL SIGNIFICANCE OF VITAMINS 



Others wanted to know what a vitamin looked hke. The first 

 crystalHne material to be isolated from a natural concentrate having 

 vitamin activity was probably nicotinic acid. It was obtained between 

 1912 and 1914 from rice bran and yeast; but unfortunately its bio- 

 logical activity was tested for antineuritic activity rather than for anti- 

 pellagra activity. The successful establishment of the chemical con- 

 stitution of several of the vitamins depended upon an enormous amount 

 of work and true chemical ability. The first of the vitamins to be given 

 serious chemical consideration was undoubtedly vitamin D. In 1925, 

 Steenbock and Black, and Hess and co-workers showed that crude 

 cholesterol could be activated by ultraviolet light, and the following 

 year ergosterol was recognized as the actual provitamin. These ob- 

 servations stimulated the interest of organic chemists in the structure of 

 sterols, a problem that had received only sporadic attention. A little 

 later, the chemical basis for the relationship between carotene and 

 vitamin A was established. It is interesting to note that, although the 

 structure of vitamins A and D received early attention, these are the 

 only well-known vitamins still not available in synthetic form. Vitamins 

 C and Bi were the first to be made synthetically, but only about ten 

 years ago. During the past decade, methods for the synthesis of ten 

 different vitamins have been perfected. 



I have merely recorded the final results without paying tribute 

 to the individual workers for their years of study of the details of 

 chemical structure. It is true that some of the work was stimulated by 

 commercial interest, but in many cases the individual workers were 

 rewarded only by the satisfaction obtained from the successful proof 

 of structure of "their" vitamin. That chemical industry did become 

 interested in the production of vitamins was indeed fortunate. The 

 availability of each new vitamin facilitated progress on the remaining 

 vitamins. 



As far as I am aware, no one has formally expressed the grati- 

 tude of laboratory workers for the large quantities of vitamins supplied 

 gratis by industry for experimental purposes. Although it is true that 

 many papers carry a footnote indicating indebtedness to a particular 

 firm "for a generous supply of crystalline vitamins," such an acknowl- 

 edgment is so common today that it is often taken for granted. I 

 have no way of estimating the total expenditure involved, for the value 

 of these gifts cannot be calculated merely by multiplying the number 



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