Partial preparative purification of leptine I from foliage of the wild potato, Solanum chacoense (Bitt.)

Leptine I, a glycoalkaloid only known to occur in the foliage of the wild p otato species Solanum chacoense (Bitt.), is a potent feeding deterrent to t he economically serious insect pest, the Colorado potato beetle (Leptinotar sa decemlineata Say). In order to demonstrate, systematically, the effectiv eness of leptine I, incorporation into synthetic beetle diet trials is nece ssary. We describe a preparative procedure for the partial purification of leptine I by a series of steps, starting with a solid-phase C-18 extraction , followed by sequential silica gel chromatography, and finally reversed-ph ase preparative HPLC. This preparation yields a white powder, containing le ptine I as the sole glycoalkaloid, with an overall purity of greater than 6 5%, and is entirely suitable for incorporation into synthetic diets.