Pyrrolizidine alkaloids (PAs) were characterized by GC-MS in inflorescences of 14 Senecio species (S. brasiliensis, S. conyzifolius, S. heterotrichius, S. oleosus, S. oxyphyllus, S. riograndensis, S. selloi, S. bonariensis, S. grossidens, S. icoglossus, S. juergensii, S. pulcher, S. ceratophylloides and S. crassiflorus) from southern Brazil, belonging to three taxonomic sections of the genus. The 1,2-saturated macrocycle diesters (such as platyphylline or rosmarinine), 1,2-saturated or unsaturated triangularine-like alkaloids such as senecioylplatinecine and senecioylretronecine were characteristic for the section Hualtatini. The section Corymbosi has, as characteristic PAs, 1,2-unsaturated 12-membered macrocyclic diesters (such as senecionine), while the section Suffrutecius is ambiguous in relation to the PA profile. The data indicate that the PA patterns are mostly in good agreement with morphological data for the sections Corymbosi and Hualtatini and that they can be useful chemotaxonomic markers at the infrageneric level. © 2003 Elsevier Science Ltd. All rights reserved.31910111022Boppré, M., Lepidoptera and pyrrolizidine alkaloids. Exemplification of complexity in chemical ecology (1990) J. Chem. Ecol., 16, pp. 165-185Bredenkamp, M.W., The mass spectrometry of pyrrolizidine alkaloids (1991) Naturally Occurring Pyrrolizidine Alkaloids, pp. 147-168. , Rizk, A.M. (Ed.). CRC Press, FloridaBremer, K., Asteraceae (1994) Cladistics and Classification, , Timber Press, Portland, Oregon, USABrown, K.S., Trigo, J.R., Ecological activities of the alkaloids (1995) The Alkaloids, 47, pp. 227-356. , Cordell, G.A. (Ed.), Academic Press, New YorkCabrera, A.L., El genero Senecio (Compositae) en Brazil, Paraguay y Uruguay (1958) Arq. Jard. Bot. Rio de Janeiro, 15, pp. 163-269Cabrera, A.L., Klein, R.M., (1975) Flora Ilustrada Catarinense, Vol. 15. Compostas 2: Tribo Senecioneae, 15. , Herbário Barbosa Rodrigues, Itajaí, SCCava, M.P., Rao, K.V., Weisbach, J.A., Raffauf, R.F., Douglas, B., The alkaloids of Cacalia floridana (1968) J. Org. Chem., 33, pp. 3570-3573Culvenor, C.C.J., Pyrrolizidine alkaloids - Occurrence and systematic importance in angiosperms (1978) Bot. Not., 131, pp. 473-486Culvenor, C.C.J., Koretskaya, N.I., Smith, L., Utkin, L.M., The structures of the pyrrolizidine alkaloids neoplatyphylline and hastanecine (1968) Aust. J. Chem., 21, pp. 1671-1673Culvenor, C.C.J., Edgar, J.A., Jago, M.V., Outteridge, A., Peterson, J.E., Smith, L.W., Hepato- and pneumotoxicity of pyrrolizidine alkaloids and derivatives in relation to molecular structure (1976) Chem. Biol. Interact., 12, pp. 299-324Hartmann, T., Chemical ecology of pyrrolizidine alkaloids (1999) Planta, 207, pp. 483-495Hartmann, T., Witte, L., Chemistry biology and chemoecology of the pyrrolizidine alkaloids (1995) Alkaloids - Chemical and Biological Perspectives, 9, pp. 155-233. , Pelletier, S.W. (Ed.), Pergamon Press, OxfordHind, D.J.N., A checklist of the Brazilian Senecioneae (Compositae) (1993) Kew Bull., 48, pp. 279-296Hirschmann, G.S., Ferro, E.A., Franco, L., Recalde, L., Theoduloz, C., Pyrrolizidine alkaloids from Senecio brasiliensis populations (1987) J. Nat. Prod., 50, pp. 770-772Klitzke, C.F., Trigo, J.R., New records of pyrrolizidine alkaloid-feeding insects. Hemiptera and Coleoptera on Senecio brasiliensis (2000) Biochem. Syst. Ecol., 28, pp. 313-318Krebs, H.C., Torsten, C., Habermehl, G.G., Pyrrolizidine alkaloid composition in six Brazilian Senecio species (1996) Phytochemistry, 43, pp. 1227-1229Liddell, J.R., Loogie, C.G., A re-investigation of the alkaloids of Senecio pterophorus (1993) Phytochemistry, 34, pp. 1629-1631Liddell, J.R., Stermitz, F.R., Barros, C.S.L., Pyrrolizidine alkaloids from Senecio oxyphyllus, a Brazilian poisonous plant (1992) Biochem. Syst. Ecol., 20, p. 393Logie, C.G., Grue, M.R., Liddell, J.R., Proton NMR spectroscopy of pyrrolizidine alkaloids (1994) Phytochemistry, 37, pp. 43-109Mattocks, A.R., (1986) Chemistry and Toxicology of Pyrrolizidine Alkaloids, , Academic Press, LondonRobins, D., Biosynthesis of pyrrolizidine alkaloids (1989) Chem. Soc. Rev., 18, pp. 375-408Stelljes, M.E., Kelley, R.B., Molyneaux, R.J., Seiber, J.N., GC-MS determination of pyrrolizidine alkaloids in four Senecio species (1991) J. Nat. Prod., 54, pp. 759-773Trigo, J.R., The chemistry of antipredator defense by secondary compounds in Neotropical Lepidoptera: Facts, perspectives and caveats (2000) J. Braz. Chem. Soc., 11, pp. 551-561Trigo, J.R., Brown, K.S., Witte, L., Hartmann, T., Ernst, L., Barata, L.E.S., Pyrrolizidine alkaloids: Different acquisition and use patterns in Apocynaceae and Solanaceae feeding ithomiine butterflies (Lepidoptera: Nymphalidae) (1996) Biol. J. Linn. Soc., 58, pp. 99-123Trigo, J.R., Brown, K.S., Henriques, S.A., Barata, L.E.S., Quantitative patterns of pyrrolizidine alkaloids in Ithomiinae butterflies (1996) Biochem. Syst. Ecol., 24, pp. 181-188Van Den Dool, H., Kratz, P.D., A generalization of the retention index system including linear temperature programmed gas-liquid partition chromatography (1963) J. Chromatogr., 11, pp. 463-471Witte, L., Ernst, L., Adam, H., Hartmann, T., Chemotypes of 2 pyrrolizidine alkaloid-containing Senecio species (1992) Phytochemistry, 31, pp. 559-565Witte, L., Rubiolo, P., Bicchi, C., Hartmann, T., Comparative analysis of pyrrolizidine alkaloids from natural sources by gas chromatography-mass spectrometry (1993) Phytochemistry, 32, pp. 187-196