THE FOLIC ACID COMPLEX 



R. Hertz ^® observed that sexually immature monkeys maintained 

 on a synthetic diet deficient in folic acid failed to show the normal 

 response to oestradiol benzoate, thus showing a similar response to 

 that exhibited by folic acid-deficient chicks (page 486). 



Fish 



According to McLaren et al.,^^ young rainbow trout developed 

 anaemia in the absence of folic acid. This was cured by the addition 

 to the diet of o-i to 0-5 mg. of folic acid per 100 g. It is worth record- 

 ing that ^-aminobenzoic acid stimulated growth in the presence of 

 folic acid, the only instance in animals where the two factors have 

 distinctive effects. 



Folic Acid and Resistance to Infection 



Monkeys exhibited an increased resistance to experimental polio- 

 myelitis when suffering from a chronic but not an acute folic acid 

 deficiency. ^^ Folic acid had no effect on experimental toxoplasmosis 

 in mice, but the protection afforded by sulphathiazole was neutralised 

 by folic acid. ^2 Similarly, the chemotherapeutic action of sulphadia- 

 zine on psittacosis virus was antagonised by _^-aminobenzoic acid and 

 pteroylglutamic acid, competitively in the former instance and non- 

 competitively in the latter. ^^ This suggests that the primary action 

 of sulphadiazine in psittacosis is against the incorporation of _/)-amino- 

 benzoic acid into pteroylglutamic acid by the virus. Large doses of 

 sulphadiazine failed to inhibit the virus when pteroylglutamic acid 

 was supplied, so that it evidently synthesises the vitamin in the 

 absence of sulphonamide and utilises it for growth. 



Folic Acid and Cancer 



Leuchtenberger et al.^^ claimed that a folic acid concentrate and 

 the crystalline fermentation L. casei factor inhibited the growth of 

 transplanted sarcomas in mice. Later ^^ they found that whereas the 

 liver L. casei factor did not produce regression of spontaneous breast 

 cancer in mice, the fermentation L. casei factor was effective in eleven 

 out of twenty-eight mice. Synthetic pteroyltriglutamic acid, 

 " Teropterin ", did not, however, produce regeneration of 6C3HED 

 tumours in C3H mice, although it partially inhibited the effect of 

 mustard gas on lymphosarcoma GCgHED.®^ 



Synthetic folic acid has been tested, with not very encouraging 

 results, on various forms of malignant disease in humans (see page 

 501). 



492 



