302 ASCORBIC ACID 



D. FUNCTIONAL ASPECTS 

 1. Functions, Locus of Action, Mode of Action 



a. Functions Attributed to Ascorbic Acid 



1. It regulates the colloidal condition of intercellular substances having 

 collagen or related substances as basic constituents. This is its most defi- 

 nitely established function. 



2. It protects hydrogen carriers, thereby preventing injurious oxidations 

 by acting as an antioxidant. An example of this type of action is to be found 

 in its relations with a-tocopherol. 



3. It promotes certain types of oxidation such as that of fatty acids and 

 the production of the oxy type of adrenal cortical hormones. ^^® 



4. It preserves a proper balance between different enzyme systems; the 

 oxidation-reduction potentials are thus maintained at certain levels. 



5. It plays a role in the formation of desoxyribonucleic acid, a substance 

 held to control the physical-chemical properties of the nuclei.^^^ 



b. Locus of Actions 



(1) Directly on the Protoplasm. This occurs particularly in the special 

 mesenchymal cells — fibroblasts, osteoblasts, odontoblasts, ameloblasts, etc. 

 Without ascorbic acid there is a failure in these special cells to differentiate, 

 mature, migrate, assume a proper orientation, and consequently a general 

 inability to function properly. Adherents of the view of direct protoplasmic 

 action have been Hansen,"* Mall,"^ Lewis,-*"" Hojer,^ Meyer,*^ Fish and 

 Harris,^"* Ham and Elliott,^^ and MacLean et aU^ Hojer,^ whose studies 

 and their presentation did much to develop this concept, summarizes his 

 observations as follows: "Scurvy reduces the nutritional state and the active 

 function of probably all the most active, most rapidly growing and highest 

 differentiated cells of the body. This reduction begins with the absence of 

 antiscorbutic in the food. It becomes manifest at a rate that varies for the 

 different cells and tissues: first in the odontoblasts, then in the osteoblasts, 

 muscle cells, lymphoid tissue, fibroblasts and salivary glands; then in the 

 liver, adrenals, chondroblasts, and last in the epithelium of the kidney. 

 The order in which the changes set in and continue in odontoblasts, osteo- 

 blasts and chondroblasts seem to argue for the notion that phylogenetically 

 older and histofunctionally less differentiated cells are later and more lightly 



1^' C D. Hughes, M. J. Swenson, G. K. Underbjerg, and J. S. Hughes, Science 116, 



252, (1952). 

 "7 B. I. Gol'dshtein, D. V. Vol'kenzou, L. G. Kondrateva, and N. D. Uryenova, 



Biokhimiya 15, 173 (1950). 

 "8 F. Hansen, Anat. Am. 16, 417 (1899). 

 199 F. Mall, Am. J. Anat. 1, 329 (1902). 

 2"'' M. R. Lewis, Carnegie Inst. Wash. Contrib. Embryology 6, 45 (1917). 



