Further Studies on the Relationship Between Xanthopterin, Folic Acid and Vitamin M

Abstract

Samples of brewers'' yeast were incubated with fresh livers of rat, chicken and monkey; the monkey livers were obtained from vit. M-deficient animals with leukopenia and anemia. Yeast which has a relatively low preformed folic acid content becomes rich in the substances which give rise to folic acid when incubated with fresh liver; 15-fold or greater increases over the preformed folic acid were obtained. The livers from the vit. M-deficient monkeys were strikingly low in preformed folic acid, supporting the belief that there is a relation between vit. M and the precursors of folic acid. Liver produced extra folic acid from yeast and also from xanthopterin when yeast was added. Chicken liver produced no extra folic acid from xanthopterin alone, as measured by Streptococcus lactis stimulation, but pro-duced folic acid from xanthopterin in the presence of yeast and also from yeast alone.