580 THE BIOCHEMISTRY OF B VITAMINS 



of folic acid increases the adult emergence to 64 per cent. Controls in the 

 absence of the analogue showed a survival value of 74 per cent. 117, 118 



Estrogen-induced growth responses of the genital tract of the chick is 

 prevented by L-rc-methylfolic acid at a concentration of 1 per cent in the 

 diet. 119 The inhibitory effect is completely prevented by injection of 4 mg 

 of folic acid four times daily. 119 It is interesting that such estrogen-in- 

 duced growth is not obtained in folic acid-deficient chicks and monkeys. 120 



Addition of L-z-methylfolic acid (50 y per cc) to human blood cell 

 cultures in a medium containing 30 to 35 per cent human umbilical cord 

 serum in a balanced salt solution results in marked erythrophagocytosis 

 by granulocytes, as compared with blood cell cultures in the absence of 

 the analogue. 121 Addition of folic acid (5 y per cc) prevents the effect 

 of the analogue. A maturation arrest in the erythroid series does not 

 develop under these conditions. 121 



Other Methylfolic Acids. Effects similar to those of z-methylfolic 

 acid have been noted recently with 9-methylfolic acid, which competi- 

 tively inhibits the utilization of folic acid for rats, mice and chicks. 116 



OH 



I 



C N CH 3 



N C C— CH— NH— f V- CO— NH— CH— CH 2 — CH 2 — COOH 



I II I \=/ I 



H 2 N— C C CH COOH 



V/ \ / 



N N 



9-methylfolic acid [N-{9-methylpteroyl)-h-glutamic acid] 



However, N 10 -methylfolic acid is almost a thousand times as effective as 

 9-methylfolic acid in competitively preventing the functions of folic acid 

 in Streptococcus faecalis R (Table 19). The N 10 -methylfolic acid, in 

 contrast to other analogues of folic acid, is capable of stimulating the 

 growth of the Rous sarcoma in folic acid-deficient chicks. 77 The N 10 - 

 methyl analogue also has an effect analogous to L-z-methylfolic acid, 

 causing marked erythrophagocytosis by granulocytes in human blood cell 

 cultures. 121 



OH 



H 2 N— C 



C N CH 3 



N C C— CH 2 — N— (' V- CO— NH— CH— CH,— CH 2 — COOH 



II I w/ I 



C CH — COOH 



N N 



N l0 -methylfolic acid [N-(N 10 -methylpteroyl)-L,-glutamic acid] 



