The Alkaloids of Heliotropium supinum L., with Observations on Viridifloric Acid

Heliotropium supinum L. contains the pyrrolizidine alkaloids supinine, heliosupine, and echinatine as major bases. Two minor alkaloids, although not obtained in a pure state, are shown to be esters of trachelanthic acid and viridifloric acid, respectively, with 7-angelylheliotridine. The N-oxide of 7-angelylheliotridine, also isolated from the total crude base, is thought to be an artefact.Viridifloric acid is shown to be (-)-erythro-2,3-dihydroxy-4-methylpentane-3-carboxylic acid. Its melting point is markedly influenced by minute amounts of tenacious impurities. The ester of supinidine and viridifloric acid has been prepared from these component substances.