Effect of Folic Acid,“4-Amino” Folic Acids and Related Substances on Growth of Chick Embryo. ∗

Abstract

Summary

The “4-amino” pteroylglutamic acids profoundly inhibit the growth of the chick embryo, with the production of developmental abnormalities. These compounds are active in the range of 0.003 to 0.005 mg/egg, and their actions are not prevented by large doses of folic acid. The “4-amino” folic acids with aspartic acid, threonine and alanine substituted for the glutamic acid are considerably less toxic but produce similar toxicological effects. Other compounds allied to folic acid are relatively non-toxic and do not possess the growth-inhibitory activity of the “4-amino” compounds.

2,6-diaminopurine, at LD30 doses, does not seem to be an active growth inhibitor, but it produces a pale embryo, presumably deficient in hemoglobin.