572 THE BIOCHEMISTRY OF B VITAMINS 



the variations in the response of pernicious anemia patients to the 

 conjugate. 46, 49 



Pteroylhexaglutamylglutamic acid is just as active as folic acid in cor- 

 recting the succinylsulfathiazole-induced leucopenia in rats if the factors 

 are administered orally. 58 Injected parenterally, the conjugate is not quite 

 so effective as folic acid. Simultaneous oral administration of a conjugase 

 inhibitor and the heptaglutamate cause a 50 per cent decrease in the 

 urinary excretion of microbiologically active forms of folic acid as com- 

 pared with controls on the conjugate alone; however, the hematologic 

 response is not decreased by the conjugase inhibitor. 58 



From these results, it appears that the hematopoietic activity of folic 

 acid derivatives may not necessarily be reflected in urinary excretion of 

 microbiologically available forms of folic acid on administration of the 

 derivatives, and may not be dependent upon preliminary formation of 

 folic acid before conversion to the active coenzyme. 



On the basis of growth and production of hemoglobin, vitamin B c con- 

 jugate (pteroylheptaglutamic acid) administered in the diet is approxi- 

 mately 60-65 per cent as active on a molar basis as folic acid for chicks. 12 

 It has been reported that livers of day-old chicks from eggs of hens main- 

 tained on a diet containing no animal protein are almost devoid of 

 pteroylheptaglutamic acid conjugase; however, vitamin Bi 2 and 4-pyri- 

 doxic acid are reported to be synergistic in producing a marked increase 

 in the conjugase activity of preparations from such livers. 93 



Also of interest is the demonstration of pteroylheptaglutamic acid 

 conjugase in the blood of turkey poults as well as other animals, including 

 human beings. 94 



No hematologic responses have been noted after administration of 

 either pteroic acid or N 10 -formylpteroic acid (rhizopterin) to patients 

 with pernicious anemia or nutritional macrocytic anemia. 53, 95 These 

 compounds are also inactive in replacing folic acid for other animals 

 as indicated in Table 18. A slight response has been reported for 

 N 10 -formylpteroic acid in replacing folic acid for Tetrahymena gelii W. 64 

 Both the formyl derivative and pteroic acid have only very slight growth- 

 promoting effect on Lactobacillus casei; 16, 24 however, the formyl deriva- 

 tive is just as effective as folic acid in the nutrition of Streptococcus 

 faecalis R. 16 Depending upon the time of incubation, the activity of 

 pteroic acid approaches that of folic acid for this organism. 65 Streptococ- 

 cus faecalis 732, Streptococcus faecalis F24, Streptococcus zymogenes 

 5C1 and Streptococcus durans 98A are also able to utilize either folic acid 

 or formylpteroic acid (rhizopterin). 96 Suspensions of resting cells of these 

 organisms as well as Streptococcus faecalis R convert formylpteroic acid 

 to folic acid or an analogous substance. 96 Streptococcus faecalis S108 A, 



