Growth Response and Vitamin B12 Tissue Levels in Vitamin B12-Deficient Rats and Chicks Fed Riboflavin, 5,6-Dimethylbenzimidazole and Related Compounds

Abstract

Several synthetic compounds were tested for their growth-promoting ability in rats and chicks maintained on vitamin B₁₂-deficient diets. The compound 1-α-D-ribofuranosido-5,6-dimethylbenzimidazole was found to be most potent. Among the other compounds possessing activity were 1-β-D-ribofuranosido-5,6-dimethylbenzimidazole, riboflavin, 1(1′-D-ribityl)-5,6-dimethylbenzimidazole, 5,6-dimethylbenzimidazole, 1,2-dimethyl-4-amino-5-ribitylaminobenzene, and 1,2-diamino-4,5-dimethylbenzene. The livers and kidneys of rats and chicks fed vitamin B₁₂-low diets supplemented with a variety of compounds containing the 5,6-dimethylbenzimidazole moiety were assayed for vitamin B₁₂ content. Only those animals fed vitamin B₁₂ had appreciable stores of this vitamin in the kidneys and livers. There appeared to be no consistent correlation between growth and tissue stores of vitamin B₁₂ when the chicks were fed several synthetic compounds. Digestion of tissues with pancreatin or trypsin prior to assay results in markedly elevated vitamin B₁₂ assays. However, there is also an increase in microbiologically-active material not destroyed by boiling in 0.2 N NaOH for one-half hour.