PREPARATIVE SEPARATION OF PYRROLIZIDINE ALKALOIDS BY HIGH-SPEED COUNTERCURRENT CHROMATOGRAPHY

We have applied a high-speed counter-current chromatography (CCC) tech nique to the separation and purification of pyrrolizidine alkaloids fr om Amsinckia tessellata, Symphytum spp., Trichodesma incanum (Boragina ceae), and Senecio douglasii var. longilobus (Asteraceae). Alkaloidal fractions were separated in a solvent system composed of a chloroform mobile phase and 0.2 M potassium phosphate buffer, of an optimum pH, a s the stationary phase. Up to 800 mg of sample could be successfully s eparated in a single run, with excellent resolution of alkaloids. Lyco psamine and several of its acetylated derivatives were resolved from a lkaloidal fractions of Amsinckia and Symphytum. However, diastereomeri c pairs such as 7-acetyl-lycopsamine and 7-acetyl-intermedine, could n ot be separated. The presence of diastereoisomers was determined by ga s chromatography-mass spectrometry. Trichodesma contained predominantl y trichodesmine, which was resolved from a small quantity of incanine. We report the electron impact mass spectrum of incanine for the first time. Resolving power of CCC was sufficient to separate the closely r elated alkaloids senecionine and seneciphylline from Senecio, in addit ion to florosenine and retrorsine. Pyrrolizidine alkaloid compositions of the four species, determined by mass spectral techniques, were con sistent with literature, except for the lack of riddelliine and the pr esence of the otonecine-based florosenine in Senecio douglasii var. lo ngilobus.