34 THE BIOCHEMISTRY OF B VITAMINS 



The extraction of nicotinamide or nicotinic acid may be accomplished 

 in various ways, depending upon the purpose. If one wishes, as is most 

 often the case, to determine the total amount of the vitamin forms present 

 and is not concerned with which form is present, he may extract a large 

 part simply by autoclaving the material with water, as suggested by Snell 

 and Wright. 52 This does not effect quantitative removal in all cases, and 

 the more common procedure involves autoclaving with N acid or some 

 similar treatment. 53 ' 54 When applied to animal tissues and milk, this 

 treatment gives results comparable with those obtained by alkaline diges- 

 tion or enzyme digestion, but with cereals the values are substantially 

 higher, due it is thought, to the conversion of some unknown substance 

 into nicotinic acid. 55, 56, 57 



Alkaline extraction in the case of cereals, especially if relatively con- 

 centrated alkali is used, gives values very much higher than by watery 

 extraction. 58 This may be due in part to the conversion of trigonelline 

 which does not function as a vitamin into nicotinic acid which does. 



Enzymatic digestion seems to give satisfactory release so far as the 

 microbiological determination is concerned, 8, 55 because nicotinamide and 

 the corresponding coenzymes are active in this test; but this method of 

 extraction has not been generally adopted. 



Considerable more research will be required before the extraction of 

 nicotinic acid and nicotinamide can be completely controlled. This phase 

 of study has not received adequate study, partly because of the lack of a 

 satisfactory chemical method which is specific for a single chemical 

 species. 



Pantothenic Acid 



Long before the vitamin properties of pantothenic acid were demon- 

 strated, it was known to exist in a bound form particularly in liver, the 

 then richest known source. 59 From this combination it was freed by 

 autolysis for purposes of concentration. 60 



The problem of extraction of pantothenic acid from tissues is different 

 from that involved in the case of the other vitamins so far discussed 

 because this vitamin is easily destroyed by hydrolytic cleavage under acid 

 or alkaline conditions. Autolysis and the use of added enzymes are the 

 available methods. Using uncooked brain and heart tissues as starting 

 materials, Cheldelin et al. found that proteolytic enzymes, pepsin, trypsin, 

 pancreatin, papain were relatively ineffective in the release of pantothenic 

 acid, and that with hog kidney and spinach, papain was ineffective. 

 "Takadiastase" in most cases gave the highest yields. Waisman et al. el 

 found more effective release to be accomplished by pancreatin digestion. 

 The increased yield due to the use of pancreatin was 2 or 3-fold in the 



