Pyrrolizidine alkaloids from Bulgarian species of the genus Senecio

Nine Bulgarian species from the genus Senecio were studied phytochemically and/or by GC-MS analysis. Senecivernine-N-oxide was isolated and identified by spectral data for the first time. Different types of pyrrolizidine alkaloids were tested for cytotoxicity on murine lymphocytes. At a concentration of 100 μg/ml, the alkaloid retroisosenine showed immunosuppressive effect.