VITAMINS 347 



symptom, though others known either clinically or experimentally 

 include mental disorders, reproductive failure, and necrosis of the liver, 

 brain, and spinal cord. 



ASCORBIC ACID 



Chemistry 



Also called vitamin C, this nutrient is a water-soluble vitamin but 

 is not considered part of the B complex. Deficiencies of this substance 

 have been reported for centuries as the disease scurvy. Famous ac- 

 counts abound in literary works of all sorts and have encouraged 

 attempts to isolate and characterize the vitamin. Now, of course, it is 

 synthesized on such a scale that it sells for $13/kg. and is used in large 

 cjuantities to fortify canned foods. 



0- 



CH.^H 



L-ascorbic acid L-dehydroascorbic acid 



H 



^Q C— CH2OH 



HOOC \ OH 







L -diketogulonic acid 



Vitamin C is a relatively strong reducing agent and is converted 

 to dehydroascorbic acid. This product is as effective physiologically 

 as ascorbic acid, probably because the reaction is readily reversible. 

 The second reaction is not physiologically reversible. A postulated 

 mechanism for the synthesis of ascorbic acid in plants has been 

 presented on page 219. The vitamin is metabolized in animals, 

 and parts of the molecule are eliminated as carbon dioxide, oxalic 

 acid, and other products by an unknown mechanism. 



Function 



Much work has failed to clarify the physiological function of vita- 

 min C. It has been suggested that this vitamin participates in the 



