IX. EFFECTS OF DEFICIENCY 191 



(loldbiM-j;- (7 (il.^^ to require PGA for pupation, xanthopterin or thymine 

 Ix'ins inetVective. PGA also increases growth and survival rates, body pig- 

 mentation, and size of the larvae. PCJA has the most marked effect during 

 I he third stage of larval life. Fraenkel et al^^ showed the need for PGA in 

 (he nutrition of the meal worm Tcnebrio moliior. Growth of the larvae of the 

 carpet beetle was increased by concentrates of PGA (Moore*^^). Grob el al.^^ 

 reported that the larvae of rice flour beetle Tribolium confusum requires two 

 unknown factors, one of which could be replaced by PGA concentrates. 



11. Relation between PGA and Ascorbic Acid 

 a. PGA and Tyrosine Metabolism 



An interesting relationship has been observed between PGA and ascor- 

 bic acid in the metabolism of tyrosine. Ingestion of large amounts of tyrosine 

 by scorbutic guinea pigs produces a large increase in the excretion of p- 

 hydroxyphenylpyruvic acid, p-hydroxyphenyllactic acid, and small amounts 

 of tyrosine. This apparent defect in tyrosine metaboUsm disappears on the 

 administration of small amounts of ascorbic acid (Sealock and Silberstein^"*) 

 The scorbutic guinea pig is thus unable to oxidatively rupture the benzene 

 ring. The failure of D-isoascorbic acid to prevent the tyrosyluria except in 

 doses twenty times that of ascorbic acid indicates that the activity of the 

 latter is specifically related to its vitamin activity and not simply to its 

 reducing properties. Painter and Zilva^^ found that the excretion of abnor- 

 mal metabolites began as early as 24 to 48 hours after the ascorbic acid was 

 withdrawn from the diet and before the tissues became depleted of this 

 vitamin. It is especially interesting that 3 hours after the administration 

 of 0.5 g. of tyrosine to guinea pigs on a scorbutic diet an amount of hydroxy- 

 phenyl compounds equivalent to half the tyrosine appeared, mainly in the 

 large intestine. Twenty-four hours later none remained in the tissues or the 

 intestine but instead had appeared in the urine. 



Reports that the high excretion of phenolic compounds by patients having 

 pernicious anemia in relapse was reduced by liver therapy^^ prompted the 

 study of the effect of PGA on the metabolism of tyrosine in the scorbutic 

 guinea pig. Woodruff el aZ.^° observed that guinea pigs on a scorbutic diet 

 and receiving 5 % tyrosine excreted 30 to 60 % of the dietary tyrosine in 

 the form of hydroxyphenyl derivatives. Administration of either 5 mg. of 



9" L. Golberg, B. De Meillon, and L. Lavoipierre, /. Expll. Biol. 21, 90 (1945). 

 " G. Fraenkel, M. Blewett, and M. Coles, Physiol. Zool. 23, 92 (1950). 

 "W. Moore, Ann. Entomol. Soc. Amer. 39, 513 (1946). 

 " C. A. Grob, T. Reichstein, and H. Rosenthal, Expericntia 1, 275 (1945). 

 9^ R. R. Sealock and H. E. Silberstein, J. Biol. Chem. 135, 251 (1940). 

 9* H. A. Painter and S. S. Zilva, Biochem. J. 41, 511 (1948). 



"M. E. Swendseid, B. Wandruff, and F. H. Bethell, ./. Lah. Clin. Med. 32, 1242 

 (1947). 



