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

Abstract

The lethality of 7 compounds structurally related to vitamin B12 was determined by injecting several doses of each compound into the albumen prior to incubation. The lethal index (percent dead/uM of inhibitor/egg) for each compound was: (I) methylamide, 0.5; (II) l,2-dimethyl-4,5-diaminobeneene, 2.8; (HI) 5,6-dimethylbenzimidazole, 3.7; (IV) 2,5-dimethylbenzimidazole, 8.0; (V) l,2-dichloro-4,5-diaminobenzene, 9.5; (VI) 2-ethyl-5-methyl-benzimidazole, 12.6 (injected Oct.-Nov., random bred, White Leghorn); (VII) 2-hepta-5-methylbenzimidazole, 15.5; and (VI) 2-ethyl-5-methyl-benzimidazole, 29.0 (injected Feb.-March, Mt. Hope, White Leghorn). The effect of vitamin B12 was tested on compounds V, VI, VII; it alone was non lethal and failed to influence the lethality of V and VII. However, high levels partially reversed VI under conditions which varied with seasonal and/or genetic differences. The lethality of the VI also varied under these conditions. The relative order of lethality of the benzimidazoles was the same as in virus inhibitory work, (Tamm et al., J. Exp. Med. 98: 245. 1953), while that of the benzenes was the same as the inhibition of microorganisms which synthesize B12 and/or riboflavin (Woolley, Proc. Soc. Exp. Biol. Med. 75: 745. 1950). The 3 inhibitors which are natural moities of vitamin B12, I, II, and III, were the least lethal of the compounds tested. The implications of these findings were discussed.