Abnormal metabolism, ascorbic acid

Since there is an abnormality of calcium metabolism in scurvy, it has been reasoned that supplementary ascorbic acid in the hen ration might help to resolve the problem of thin eggshell during summer heat. Some reports show improved shell soundness during high environmental temperatures others do not. According to Thorton (164,165) and Thorton... 

Knowledge of metabolic pathways of phenylalanine and tyrosine has been obtained by study of certain inborn errors of metabolism in man (see Chapter 5). Of particular interest in human nutrition is the relationship of ascorbic acid and folic acid in the metabolism of these two amino acids. In premature infants or in persons with scurvy, the feeding of high protein diets or the administration of tyrosine leads to hydroxyphenyluria. Both ascorbic acid and folic acid (large doses) will prevent the excretion of abnormal quantities of hydroxyphenyl derivatives. Recently, Sealock... 

Folic Acid—Ascorbic Acid Relationships. Folic acid and ascorbic acid have some interesting metabolic relationships, among which is a role in tyrosine metabolism. Abnormal excretion of tyrosine metabolites occurs in human infants with scurvy, and in premature infants when the diet is high in this amino acid. Folic acid, in large doses, will prevent or relieve this abnormal excretion, as does ascorbic acid. Folic acid exerts a similar action in scorbutic guinea pigs. ... 

Although ascorbic acid has been shown to have many biologic functions, little is known of its chemical role in metabolic processes. Recently, Sealock and Goodland and Knox and LeMay-Knox have demonstrated that ascorbic acid is a coenzyme in the oxidation of tyrosine. This is the only section of the vitamin s activity in which the molecular processes that depend on it are clearly understood (Chapter 11). This explains the abnormal excretion of tyrosine metabolites in human scurvy and the return to... 

The adrenal cortex is very rich in steroids and in ascorbic acid, and is either a factory or a storage depot for these reactants. The metabolic disturbances due to cortical deficiency may be associated with lack of ascorbic acid, and there is evidence that this vitamin is of therapeutic value in the treatment of Addison s disease (Sclare, 1937). The sexual disturbances associated with cortical dysfunction in the female originate probably from abnormal sterol metabolism, as a result of which the tissue either produces an androgen or fails to destroy one. 

Uric acid is the principal final product of purine metabolism in the human body. Abnormal levels of uric acid are symptoms of several diseases, including gout and hyperurichemia. In a healthy human being, normal concentrations of uric acid in the blood are 120-450 pM and in urine are about 2 mM. Ascorbic acid is the major interfering electroactive species, which oxidizes at a potential... 

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