RELATIONSHIPS BETWEEN BIOTIN AND VITAMIN B12. EFFECTS OF BIOTIN AND VITAMIN B12 ON FOLIC ACID METABOLISM.

1. The effects of dietary biotin compared with vitamin B(12) on the total content and on the distribution of the various folate derivatives in the liver of rats given a biotin-free diet have been studied. The effect of both vitamins on the conversion in vitro of folic acid into citrovorum factor in the same experimental conditions was also examined. 2. In biotin-treated rats as well as in vitamin B(12)-treated rats the total content of folic acid-active substances measured microbiologically by Pediococcus cerevisiae, Streptococcus faecalis and Lactobacillus casei is significantly higher than that in biotin-deficient rats. The liver distribution of various folate derivatives in the three groups of animals is also markedly modified. 3. The amount of citrovorum factor formed in systems with liver homogenate of rats receiving biotin or vitamin B(12) is higher than that with liver homogenates of deficient rats. 4. The results obtained demonstrate the influence of biotin in the metabolism of folic acid, and the similar actions at this level of both biotin and vitamin B(12). These results are discussed in relation to the participation of the two vitamins in the metabolism of C(1) units, as a biochemical interpretation of the relationships between vitamin B(12) and biotin.