ABSTRACT
The toxic effect of bracken fern on livestock has attracted the attention of veterinary scientists since the end of the last century. The carcinogenicity of bracken fern was demonstrated most clearly by the experiment of Evans and Mason showing that rats fed a diet containing bracken fern developed multiple intestinal adenocarcinomas. It was also demonstrated that ptaquiloside is a causative principle of cattle bracken poisoning. Thus, separation using the resin adsorption and the solvent partitions described above provided the fraction (V-A) exhibiting strong carcinogenicity. Recently, an efficient and convenient method for the isolation of ptaquiloside was developed. Styrene and styrene oxide are known to be mutagenic in Salmonella typhimurium. It was strongly suggested that not only ptaquiloside, but also p-hydroxystyrene glycosides are the causative principle of these hyperplastic nodules of the liver.
