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We developed an immunoassay with antibodies against retrorsine to detect the closely related senecionine, the main alkaloid in various Asteraceae. Sensitivity is about 23 pg (68 fmol) for senecionine. Cross reactivity of monocrotalin, retrorsine N-oxide, senkirkine (< 0.1%), and seneciphylline (3.6-34.5%) was resolved. The alkaloid content in leaves of Petasites hybridus (Asteraceae) was determined to be 3.86 ppm, calculated as senecionine, which was far less than in rhizomes (104.8 ppm). Additionally, we proved specificity by taking immunograms from different parts of Petasites hybridus. The test is a suitable tool for assessing the toxic potential of medicinal plants containing senecionine.

A gas-chromatographical method is described on which seven pyrrolizidine alkaloids (Fuchsisenecionine, Senecionine, Senecivernine, Senkirkine, Retrorsine, O (7)-Angelylheliotridine and Heliotrine) are determinated in a qualitative way and their ratio of concentration in Senecio fuchsii, vernalis, inaequidens and ovirensis, ssp. gaudinii.

Otosenine and senecionine/seneciphyllme were isolated from Senecio aegyptius and S. desfontainei, respectively. Senecionine and seneciphylline easily cocrystallize; m.p. and IR-spectra of mixtures of both alkaloids and their separation by PC are described. IR evidence of individual alkaloids and of the alkaloid-pair are shown.

A new pyrrolizidine alkaloid dihydroretrorsine was isolated from roots of S. SUBULATUS Don ex Hook et Arn var. ERECTUS together with the previously known senecionine and retrorsine. From the roots of S. GLANDULOSUS Don ex Hook et Arn was isolated integerrimine and the mixture of the retrorsine and uraramine isomers. The structure of dihydoretrorsine was deduced by spectral and chemicals means.