Sarracine

Complete 1H NMR assignments of pyrrolizidine alkaloids and a new eudesmanoid from Senecio polypodioides.[Pubmed:24574143]

Magn Reson Chem. 2014 May;52(5):251-7.

Chemical investigation of the aerial parts of Senecio polypodioides lead to the isolation of the new eudesmanoid 1beta-angeloyloxyeudesm-7-ene-4beta,9alpha-diol (1) and the known dirhamnosyl flavonoid lespidin (3), while from roots, the known 7beta-angeloyloxy-1-methylene-8alpha-pyrrolizidine (5) and Sarracine N-oxide (6), as well as the new neoSarracine N-oxide (8), were obtained. The structure of 1 and 8 was elucidated by spectral means. Complete assignments of the (1)H NMR data for 5, 6, Sarracine (7), and 8 were made using one-dimensional and two-dimensional NMR experiments and by application of the iterative full spin analysis of the PERCH NMR software.

Acquisition, transformation and maintenance of plant pyrrolizidine alkaloids by the polyphagous arctiid Grammia geneura.[Pubmed:16102415]

Insect Biochem Mol Biol. 2005 Oct;35(10):1083-99.

The polyphagous arctiid Grammia geneura appears well adapted to utilize for its protection plant pyrrolizidine alkaloids of almost all known structural types. Plant-acquired alkaloids that are maintained through all life-stages include various classes of macrocyclic diesters (typically occurring in the Asteraceae tribe Senecioneae and Fabaceae), macrocyclic triesters (Apocynaceae) and open-chain esters of the lycopsamine type (Asteraceae tribe Eupatorieae, Boraginaceae and Apocynaceae). As in other arctiids, all sequestered and processed pyrrolizidine alkaloids are maintained as non-toxic N-oxides. The only type of pyrrolizidine alkaloids that is neither sequestered nor metabolized are the pro-toxic otonecine-derivatives, e.g. the senecionine analog senkirkine that cannot be detoxified by N-oxidation. In its sequestration behavior, G. geneura resembles the previously studied highly polyphagous Estigmene acrea. Both arctiids are adapted to exploit pyrrolizidine alkaloid-containing plants as "drug sources". However, unlike E. acrea, G. geneura is not known to synthesize the pyrrolizidine-derived male courtship pheromone, hydroxydanaidal, and differs distinctly in its metabolic processing of the plant-acquired alkaloids. Necine bases obtained from plant acquired pyrrolizidine alkaloids are re-esterified yielding two distinct classes of insect-specific ester alkaloids, the creatonotines, also present in E. acrea, and the callimorphines, missing in E. acrea. The creatonotines are preferentially found in pupae; in adults they are largely replaced by the callimorphines. Before eclosion the creatonotines are apparently converted into the callimorphines by trans-esterification. Open-chain ester alkaloids such as the platynecine ester Sarracine and the orchid alkaloid phalaenopsine, that do not possess the unique necic acid moiety of the lycopsamine type, are sequestered by larvae but they need to be converted into the respective creatonotines and callimorphines by trans-esterification in order to be transferred to the adult stage. In the case of the orchid alkaloids, evidence is presented that during this processing the necine base (trachelanthamidine) is converted into its 7-(R)-hydroxy derivative (turneforcidine), indicating the ability of G. geneura to introduce a hydroxyl group at C-7 of a necine base. The creatonotines and callimorphines display a striking similarity to plant necine monoesters of the lycopsamine type to which G. geneura is well adapted. The possible function of insect-specific trans-esterification in the acquisition of necine bases derived from plant acquired alkaloids, especially from those that cannot be maintained through all life-stages, is discussed.

Alkaloids from the roots of Senecio macedonicus Griseb.[Pubmed:12440711]

Z Naturforsch C. 2002 Sep-Oct;57(9-10):780-4.

The new alkaloids 7-,9-diangeloylplatynecine (1) and 8-epiSarracine N-oxide (2), were isolated and identified from the roots of Senecio macedonicus. Another one, 8-epineoSarracine was detected by GC/MS analyses of the crude alkaloid mixture. The cytotoxicity and biological activity of the alkaloids were tested on normal murine spleen lymphocytes and P3U1 mouse myeloma.

Pyrrolizidine alkaloids in an overwintering population of monarch butterflies (Danaus plexippus) in California.[Pubmed:24263818]

J Chem Ecol. 1990 May;16(5):1459-70.

California overwintering monarch butterflies contain both pyrrolizidine alkaloids (PAs) and theirN-oxides. Analysis of 76 individual monarchs by TLC, HPLC, GLC, and GC-MS has shown the presence of three types of PAs, the saturated diester Sarracine, the saturated monoester 7-angelylplatynecine, and the unsaturated dialcohol retronecine. Monarchs arriving at the overwintering site in Santa Cruz, California, showed a wide variation in both the type and amount of PA present. Those sampled after a PA-containing plant (Senecio mikanioides) had bloomed at the site showed an altered PA profile. While the plant was found to contain Sarracine and 7-angelylplatynecine, which are nontoxic to mammals, the monarchs showed an increase in retronecine levels, a toxic PA, after the plant bloom. Apparently monarchs utilize PA-containing plants both en route to their overwintering site and at the site, and potentially alter those PAs to forms toxic to mammals.

Pyrrolizidine alkaloids: actions on muscarinic receptors in the guinea-pig ileum.[Pubmed:5579465]

Br J Pharmacol. 1971 Apr;41(4):683-90.

1. Eleven pyrrolizidine alkaloids have been tested on the isolated guinea-pig ileum preparation.2. Platyphylline, supinine, heleurine and cynaustraline were more potent in antagonizing responses to acetylcholine and carbachol than responses to histamine. Their anticholinergic activity appeared to involve a competitive mechanism.3. Lasiocarpine, monocrotaline, spectabiline, Sarracine, 7-angelylheliotridine, heliotrine and senecionine had similar antagonistic potencies against responses to both acetylcholine and histamine.4. The alkaloids had no appreciable activity as antagonists of acetylcholine in the isolated toad rectus abdominis preparation.5. These results are discussed with respect to interactions of the alkaloids at receptor sites involved in anticholinergic activity at the muscarinic receptor.