35 research outputs found

    Alkaloids from three ethnomedicinal Haemanthus species: H. albiflos, H. deformis and H. pauculifolius (Amaryllidaceae)

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    Three closely-allied ethnomedicinal Haemanthus (Amaryllidaceae) species from the summer-rainfall region of South Africa have been phytochemically investigated and have yielded a range of isoquinoline alkaloids. H. albiflos yielded homolycorine, albomaculine and the O-methyl-lycorenium salt. From H. pauculifolius, homolycorine, the novel paucamine present as a salt, and the quaternary salts of homolycorine, montanine and manthidine were isolated. H. deformis yielded coccinine, montanine and the quaternary salt of manthidine

    Molecular phylogenetics of subfamily Urgineoideae (Hyacinthaceae): Toward a coherent generic circumscription informed by molecular, morphological, and distributional data

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    The taxonomy and systematics of Urgineoideae (Hyacinthaceae) have been controversial in recent decades, with contrasting taxonomic treatments proposed based on preliminary and partial studies that have focused on morphology and/or solely plastid DNA sequence data. Some authors have recognized only two genera, with a very broadly conceived Drimia, while others have accepted several genera that, although better defined morphologically, were doubtfully monophyletic. Here, we present phylogenetic analyses involving four plastid DNA regions (trnL intron, trnL-F spacer, matK, and the trnCGCA-ycf6 intergenic region), a nuclear region (Agt1), and a selection of 40 morphological characters. Our study covers 293 samples and ca. 160 species of Urgineoideae (ca. 80% of its global diversity). Bayesian inference, maximum likelihood, and maximum parsimony analyses were performed to derive the phylogenetic patterns. The combination of data yielded phylogenetic trees with 31 well-defined clades or lineages, most corresponding to previously described genera, although some have required description or revised circumscription. As with other monocot families, a considerable degree of homoplasy was observed in morphological characters, especially in those groups with unspecialized flowers; nonetheless, consistent syndromes of traditional and novel characters are shown to support clade recognition at genus rank. The forthcoming revised classification of Urgineoideae is outlined here

    New combinations in the tribe Urgineeae (Asparagaceae subfam. Scilloideae) with comments on contrasting taxonomic treatments

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    As part of a taxonomic revision of tribe Urgineeae, and informed by morphological and phylogenetic evidence obtained in the last decade, we present 17 new combinations in Austronea, Indurgia, Schizobasis, Tenicroa, Thuranthos, Urgineopsis, and Vera-duthiea. These are for taxa recently described in Drimia sensu latissimo or otherwise named during the past century. We include type information for all considered taxa and designate lectotypes for Drimia pauciflora, Urginea salmonea and U. sebirii. We discuss recent analytic and synthetic approaches to taxonomic arrangements for the Urgineeae and reinforce the support of an analytic treatment that recognises several genera characterised by distinct syndromes of morphological characters, biogeography and molecular evidence

    Modeling the Subsurface Structure of Sunspots

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    While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local helioseismology is the only means by which we can investigate subphotospheric structure. However, as current linear inversion techniques do not yet allow helioseismology to probe the internal structure with sufficient confidence to distinguish between the monolith and cluster models, the development of physically realistic sunspot models are a priority for helioseismologists. This is because they are not only important indicators of the variety of physical effects that may influence helioseismic inferences in active regions, but they also enable detailed assessments of the validity of helioseismic interpretations through numerical forward modeling. In this paper, we provide a critical review of the existing sunspot models and an overview of numerical methods employed to model wave propagation through model sunspots. We then carry out an helioseismic analysis of the sunspot in Active Region 9787 and address the serious inconsistencies uncovered by \citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find that this sunspot is most probably associated with a shallow, positive wave-speed perturbation (unlike the traditional two-layer model) and that travel-time measurements are consistent with a horizontal outflow in the surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic

    Organ-specific production of alkaloids from bulbs and seeds of Crinum stuhlmannii subsp. delagoense (Amaryllidaceae)

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    The phytochemistry of both bulbs and seeds of the ethnomedicinal Crinum stuhlmannii subsp. delagoense (Amaryllidaceae) was studied, sourced from a single location simultaneously. Eight alkaloids, including two previously unreported ones, N-methyl-haemanthamide (nivanine), and N-methyl-ent-delagoenine, were isolated along with lycorine, 8,9-methylenedioxophenanthridine, 6-hydroxycrinamine, 6-ethoxycrinamine, haemanthamine and hamayne. Compounds isolated were tested for acetylcholinesterase inhibition

    Organ-specific production of alkaloids from bulbs and seeds of Crinum stuhlmannii subsp. delagoense (Amaryllidaceae)

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    The phytochemistry of both bulbs and seeds of the ethnomedicinal Crinum stuhlmannii subsp. delagoense (Amaryllidaceae) was studied, sourced from a single location simultaneously. Eight alkaloids, including two previously unreported ones, N-methyl-haemanthamide (nivanine), and N-methyl-ent-delagoenine, were isolated along with lycorine, 8,9-methylenedioxophenanthridine, 6-hydroxycrinamine, 6-ethoxycrinamine, haemanthamine and hamayne. Compounds isolated were tested for acetylcholinesterase inhibition

    Novel alkaloids and a ceramide from Brunsvigia natalensis (Amaryllidaceae) and their anti-neoplastic activity

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    Two new 5,10b-ethanophenanthridine bridge alkaloids, 3-O-methyl–epi–vittatine, 1, and crouchinine, 2, (2R)-7-hydroxyflavan, 3, and a novel ceramide, brunsceramide, were isolated from the bulbs of Brunsvigia natalensis. (2R)-7-Hydroxyflavan showed total growth inhibition in the 55–60 ppm range against the melanoma (UACC62), breast (MCF7) and renal (TK10) cancer cell lines. 3-O-Methyl–epi–vittatine, 1, and bruns-ceramide, 4, were inactive against the cell lines tested
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