An Amide Possessing Insecticidal Properties From the Roots of Erigeron Affinis Dc.

Abstract

Investigations of foreign and domestic plants are continually in progress in the Bureau of Entomology and Plant Quarantine for the discovery and development of new insecticides to replace those the supply of which has been curtailed by the war.In the course of these investigations attention was directed to the roots of the Mexican plant Erigeron affinis DC.1 (family Compositae), commonly called "peritre del pais" and "chilcuan." It grows in the vicinity of Mexico City, where the roots are employed in the preparation of native insecticides.That the petroleum ether extractive (3.3%, dry roots) prepared in this laboratory from the ground roots contained the toxic constituents was indicated by tests against codling moth larvae, adult mosquitoes, and several leaf-eating insects, and it proved to have the same order of paralyzing action and toxicity to houseflies as the pyrethrins.2The toxic fraction (1.9%, dry roots) was isolated from the petroleum ether extractive by the method that Barthel, Haller, and LaForge (1) employed for the preparation of pyrethrin concentrates for use in aerosols. Briefly, the nitromethane-soluble portion extracted from the petroleum ether extractive was passed through a column of activated carbon. When the solvent was removed from the purified nitromethane solution at reduced pressure, an oily residue possessing insecticidal activity was obtained, which was distilled at reduced pressure, and yielded 1.08% (dry-root basis) of light yellow distillate (b.p. 160-165°, p = 0.3-0.5 mm.), which crystallized when cooled but melted on standing at room temperature.The substance produced a burning, paralytic effect on the tongue similar t<> that caused by pyrethrin concentrates. It was soluble in organic solvents and contained nitrogen, but it was insoluble in aqueous alkali and acid. It rapidly decolorized a dilute chloroform solution of bromine and, on acid hydrolysis, yielded an acid and a base. Although the free acid was not identified, the base was found to be isobutylamine by determination of the melting point and the chlorine content of the base-hydrochloride and the melting point of the basechloroplatinate, and by comparison with authentic materials. The substance 1 The first specimen of roots was submitted under this name by Agencias Selectas, S. A., Mexico City. Subsequent samples were obtained through the courtesy of the Division of Fruitfly Investigations, Bureau of Entomology and Plant Quarantine, Mexico City. Attempts are being made to obtain a botanical specimen for confirmation of this identification. 2 The tests against the codling moth were made by E. H. Siegler; against mosquitoes by J. H. Fales and A. E. Routson; against several leaf-eating insects by Clemence Levin, and against the housefly by W. A. Gersdorff, all of this Bureau. Detailed results of their testswill be published elsewhere by them.

Alkamides: a critical reconsideration of a multifunctional class of unsaturated fatty acid amides

“…Asano and Kanematsu (1927) initially concluded an unsaturated C 10 isobutylamide with an allenic structure, and later (1932), a deca-4,6-dienoic acid isobutylamide. The correct structure of spilanthol, isolated from the roots of H. longipes, was suggested to be either a deca-2,6,8-or 2,5,7-trienoic acid isobutylamide (Acree et al 1945). Since this plant was originally wrongly identified as Erigeron affinis, the compound was named affinin.…”

“…Similar insecticidal activities are known from the roots of H. longipes traded in Mexico under the Nahuatl names of ''chilcuague' ' and ''chilmecatl'' (Molina-Torres et al 1996). Here, the major insecticidal compound was identified as spilanthol (92a) (Crombie et al 1963), originally published as ''affinin'' (Acree et al 1945). Toxicity to house flies was also observed in petroleum ether extracts of three further American Heliopsis species (Gersdorff and Mitlin 1950).…”

Molluscicidal activity of affinin and other isobutylamides from the asteraceae

“…For example affinin (= spilanthol, N-isobutyl-2,6,8_decatrienamide, 1) is present in the roots of Heliopsis longipes (A. Gray) Blake [7], the leaves of Spilanthes oleraceae Jacq [S] and we have identified it in the flowers of Wedelia parviceps Blake. These three species are used in folk medicine for their analgesic effect in Mexico [9], Belize [lo] and in the Far East [6], and the insecticidal uses of H. longipes have been noted [9].…”

“…We now describe the isolation and identification of dhurrin from Cercocurpus fedifolius Nutt. (Rosaceae-Rosoideae), a shrub or tree, growing in the western parts of the U.S.A. [7].…”

Analgesic activity ofHeliopsis longipesand its effect on the nervous system

“…This species is commonly called "chilcuague", "chilcuán", "pelitre", golden root and Aztec root (Martínez, 1967). An alkamide (Figure 1), the N-isobutyl-2E,6Z,8E-decatrienamide, named affinin, was isolated from this root (Acree et al, 1945). Since the isolation of this molecule, several studies have been conducted with different species of the same genus, demonstrating that root extracts of H. scabra Dunal, H. parvifolia A.…”