Lethal Effect of Certain Benzimidazoles and Benzenes on Early Chick Embryo. ∗ †

Summary

(1) The lethality of 7 inhibitors structurally related to Vit. B₁₂ was determined in chick embryos by injecting several doses of each of them into the albumen prior to incubation. (2) Vit. B₁₂ alone was nonlethal and failed to influence the lethality of 2-hepta-5-methylbenzimidazole and 1, 2-dichloro-4, 5-diaminobenzene. (3) Lethality of 2-ethyl-5-methylbenzimidazole as well as its partial reversal by high levels of Vit. B₁₂ varied with seasonal and/or genetic differences. (4) The relative order of lethality of benzimidazoles was the same as in virus inhibitory work, while that of benzenes was the same as the inhibition of microorganisms which synthesize B₁₂ and/or riboflavin. (5) The 3 inhibitors which are natural moieties of Vit. B₁₂, methylamide, 1, 2-dimethyl-4, 5-diaminobenzene, and 5, 6-dimethylbenzimidazole, were the least lethal of the compounds tested. The implications of these findings are discussed.