South African fish poisonous plants VI. Isolation and study of Saponins from Neorautanenia edulis C.A. SM.

Abstract

The object of the present investigation was to extract and isolate the fish-toxic saponin present in the tuber and the aerial portions of Neorautanenia Edulis C.A. Sm. Various methods of extraction were attempted, and the best found to be that with hot 95% ethyl alcohol. Regarding the isolation of the saponin, it was found that the etherate formation with the alcoholic extract, proved to be the most satisfying. Various other methods were also tried, but none of them gave a fish-toxic saponin. Toxicity tests on fish were carried out, and the most toxic compound found to be that from the etherate formation, mentioned above. The toxic compounds were further purified by extraction with ethyl alcohol, extracting the saponin and leaving an insoluble material which was identified as cane sugar. Various methods of hydrolysis were attempted, but the saponin was resinified by the concentrated hydrochloric acid. The purest form of the toxic saponin obtained had a yellow syrupy nature. It was very toxic, to fish, but could not be hydrolised in order to identify it.