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A phytochemical study of Robinsonecio gerberifolius afforded six new sesquiterpenoids, two oplopane (1and 2) and four eremophilane derivatives (3-6). The structures of these compounds were elucidated on spectroscopic grounds, and the absolute configurations of compounds 3 and 4 were established from CD analysis. The known 3beta-angeloyloxy-1,10-epoxyfuranoeremophilane (7) was also isolated, and its stereochemistry was revised. The cytotoxic activities of compounds 1-7 were determined against five human cancer cell lines.

A phytochemical study of Roldana barba-johannis afforded two triterpenic esters, an eremophilanolide and three compounds structurally related to the antioxidants vitamin E and plastoquinone. Evaluation of the anti-inflammatory and antioxidant activities of sargahydroquinoic acid, sargachromenol, their mixture, and their methyl esters showed that most of them are antioxidant and anti-inflammatory agents.

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Two new 13-membered macrocyclic pyrrolizidine alkaloids, (13R)-13-hydroxyretroisosenine (2b) and (12S)-12-hydroxyretroisosenine (2c), have been isolated from Senecio roseus and Senecio helodes. Their structures were established from spectral and chemical studies including 2D NMR. The hydrochloride of retroisosenine (2a·HCl) was also isolated, and its absolute configuration was determined by X-ray diffraction analysis.

Two collections of Senecio callosus from different regions of Mexico contained a structural diversity of pyrrolizidine alkaloids (PAs), which may contribute to the easy adaptation of this species. In addition to some known compounds, two new PAs (1 and 2) were isolated, and their structures were established by chemical transformations and spectroscopic studies.

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