Publications by authors named "Martin W Callmander"

Article Synopsis
  • Angiosperms are vital for ecosystems and human life, making it important to understand their evolutionary history to grasp their ecological dominance.
  • The study builds an extensive tree of life for about 8,000 angiosperm genera using 353 nuclear genes, significantly increasing the sampling size and refining earlier classifications.
  • The findings reveal a complex evolutionary history marked by high gene tree conflict and rapid diversification, particularly during the early angiosperm evolution, with shifts in diversification rates linked to global temperature changes.
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Premise: The economically important, cosmopolitan soapberry family (Sapindaceae) comprises ca. 1900 species in 144 genera. Since the seminal work of Radlkofer, several authors have attempted to overcome challenges presented by the family's complex infra-familial classification.

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New Guinea is the world's largest tropical island and has fascinated naturalists for centuries. Home to some of the best-preserved ecosystems on the planet and to intact ecological gradients-from mangroves to tropical alpine grasslands-that are unmatched in the Asia-Pacific region, it is a globally recognized centre of biological and cultural diversity. So far, however, there has been no attempt to critically catalogue the entire vascular plant diversity of New Guinea.

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This study presents the most complete generic phylogenetic framework to date for the tribe Coleeae (Bignoniaceae), which is endemic to Madagascar and the other smaller islands in the western part of the Indian Ocean. The study is based on plastid and nuclear DNA regions and includes 47 species representing the five currently recognized genera (including all the species occurring in the western Indian Ocean region). Bayesian and maximum likelihood analyses supported (i) the monophyly of the tribe, (ii) the monophyly of Phylloctenium, Phyllarthron and Rhodocolea and (iii) the paraphyly of Colea due to the inclusion of species of Ophiocolea.

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An ethanol extract of leaves of the plant species Malleastrum sp. collected in northern Madagascar afforded the new clerodane diterpene 18-oxo-cleroda-3,13-dien-16,15-olide (1), together with the three known clerodane diterpenes 16,18-dihydroxykolavenic acid lactone (2), solidagolactone (3) and (-)-kolavenol (4), and the known labdane diterpene 3-oxo-ent-Iabda-8(17),13-dien-15,16-olide (5). Compounds 1, 3, and 4 showed moderate antiproliferative activities against the A2780 ovarian cancer cell line, with the IC50 values of 3.

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Antiproliferative bioassay-guided fractionation of the ethanolic extract of the endemic Madagascan plant Metaporana sericosepala led to the first natural product isolation of a butenolide diterpene, which was synthesized during an anti-inflammatory study in 1988. The structure of the compound was elucidated as 3-homofarnesyl-4-hydroxybutenolide (1) by analysis of its spectroscopic data, including 1D- and 2D-NMR data and chemical evidence. The once synthetic compound can now also be considered as a natural product.

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The two new lignans 3α-O-(β-D-glucopyranosyl)desoxypodophyllotoxin (1) and 4-O-(β-D-glucopyranosyl)dehydropodophyllotoxin (2) were isolated from Cleistanthus boivinianus, together with the known lignans deoxypicropodophyllotoxin (3), (±)-β-apopicropodophyllin (4), (-)-desoxypodophyllotoxin (5), (-)-yatein (6), and β-peltatin-5-O-β-D-glucopyranoside (7). The structures of all compounds were characterized by spectroscopic techniques. Compounds 1, 4, and 5 showed potent antiproliferative activities against the A2780 ovarian cancer cell line, with IC50 values of 33.

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As part of the International Cooperative Biodiversity Group (ICBG) program, in a search for antiproliferative compounds, an ethanol extract of Polyscias duplicata was investigated due to its antiproliferative activity against the A2780 human ovarian cell cancer line (IC50 6 µg/mL). Seven known oleanane glycosides, 3β-[(α-L-arabinopyranosyl)oxy]-16α-hydroxyolean-12-en-28-oic acid (1, IC50 8 µM), 3β-[(α-L-arabinopyranosyl)oxy]-16α,23-dihydroxyolean-12-en-18-oic acid (2, IC50 13 µM), 3β-[(O-β-D-glucopyranosyl-(t-->3)-α-L-arabinopyranosyl)oxy]-16α-hydroxyolean-12-en-28-oic acid (3, IC50 7 µM), 3β-[(O-α-L-rhamnopyranosyl-(1-2)-α-L-arabinopyranosyl)oxy]-16α-hydroxyolean-12-en-28-oic acid (4, IC50 2.8 µM), 3β-[(O-β-D-glucopyranosyl-(l-->3)-α-L- arabinopyranosyl)oxy]-23-hydroxyolean-12-en-28-oic acid (5, IC50 10 µM), β-[(O-α-L-rhamnopyranosyl-(-1.

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There is increased evidence that incorporating evolutionary history directly in conservation actions is beneficial, particularly given the likelihood that extinction is not random and that phylogenetic diversity (PD) is lost at higher rates than species diversity. This evidence is even more compelling in biodiversity hotspots, such as Madagascar, where less than 10% of the original vegetation remains. Here, we use the Leguminosae, an ecologically and economically important plant family, and a combination of phylogenetics and species distribution modelling, to assess biodiversity patterns and identify regions, coevolutionary processes and ecological factors that are important in shaping this diversity, especially during the Quaternary.

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Pandanaceae (screwpines) is a monocot family composed of c. 750 species widely distributed in the Paleotropics. It has been proposed that the family may have a Gondwanan origin with an extant Paleotropical distribution resulting from the breakup of that supercontinent.

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In a continuing collaboration in a search for new antiproliferative compounds in Madagascar as part of an International Cooperative Biodiversity Group (ICBG), an ethanol extract of Molinaea retusa Radlk. (Sapindaceae) was investigated on the basis of its moderate antiproliferative activity against the A2780 human ovarian cancer cell line (IC50 16 microg/mL). One new compound, 2", 3", 4", 6'-de-O-acetylcupacinoside (1, IC50 15.

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Bioassay-directed fractionation of the leaf and root extracts of the antiproliferative Madagascar plant Stuhlmannia moavi afforded 6-acetyl-5,8-dihydroxy-2-methoxy-7-methyl-1,4-naphthoquinone (stuhlmoavin, 1) as the most active compound, with an IC50 value of 8.1 μM against the A2780 human ovarian cancer cell line, as well as the known homoisoflavonoid bonducellin (2) and the stilbenoids 3,4,5'-trihydroxy-3'-methoxy-trans-stilbene (3), piceatannol (4), resveratrol (5), rhapontigenin (6), and isorhapontigenin (7). The structure elucidation of all compounds was based on NMR and mass spectroscopic data, and the structure of 1 was confirmed by a single crystal X-ray analysis.

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Antiproliferative bioassay-guided fractionation of the ethanol extract of the stems of Anisocycla grandidieri led to the isolation of the known alkaloids stebisimine (1), (+)-1,2-dehydrotelobine (2), (+)-2'-norcocsuline (3) and puetogaline B (4). Herein, we report the full NMR assignments of all compounds and the X-ray crystallography of single crystals of compounds 1 and 3. Compounds 2 and 3 showed moderate antiproliferative activity against the A2780 human ovarian cancer cell line with IC50 values of 4.

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Bioassay-guided fractionation of an ethanol extract of the leaves and inflorescence of Mallotus oppositifolius collected in Madagascar led to the isolation of the two new bioactive dimeric phloroglucinols mallotojaponins B (1) and C (2), together with the known mallotophenone (3). The structures of the new compounds were determined on the basis of spectroscopic evidence, including their 1D- and 2D-NMR spectra, mass spectrometry, and an X-ray crystal structure. Compounds 1 and 2 showed potent antimalarial activity against chloroquine-resistant Plasmodium falciparum, with IC50 values of 0.

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Investigation of the endemic Madagascan plant Sterculia taiva Baill. (Malvaceae) for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of two new bioactive calamenene-type sesquiterpenoids, named tavinin A (2) and epi-tavinin A (3) together with the known sesquiterpenoid mansonone G (1). The structures of the two new compounds were elucidated based on analysis of their 1D and 2D NMR spectra and mass spectrometric data, and were confirmed by de novo synthesis.

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Antiproliferative bioassay-guided fractionation of the ethanol extract of the endemic Malagasy Rubiaceous plant Tarenna grevei led to the isolation of two new antiproliferative oxygenated oleanane triterpene saponins. The structures of the two active compounds were elucidated as 23-hydroxylongispinogenin 3-O-beta-D-glucopyranoside (1) and longispinogenin 3-O-beta-D-glucopyranosyl (1 --> 2)-beta-D-glucopyranoside (3) by analyses of their spectral data including 1D- and 2D-NMR spectroscopy and chemical evidence. Compounds 1 and 3 displayed moderate antiproliferative activity against the A2780 ovarian cancer cell line with IC50 values of 7.

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Investigation of the endemic Madagascan plant Uvaria sp. for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of two new acetogenins. The structures of these two compounds were elucidated on the basis of analysis of their 1D and 2D NMR spectra, circular dichroism, and mass spectrometric data, together with chemical modification.

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A taxonomic revision of the genus Gouania Jacq. (Rhamnaceae) is presented for Madagascar and the other western Indian Ocean islands. Seventeen species are recognized, of which nine are described and published as new (all endemic to Madagascar): G.

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Bioassay guided fractionation of the ethanol extract of a new endemic species of the genus Astrotrichilia led to the isolation of the new antiproliferative 3-(4'-hydroxy-2',3'-dihydroprenyl)-4,6-dimethoxy-5-methylcoumarin, named astrotricoumarin (8) with an IC50 value of 6.8 microM against the A2780 cell line. The structure of compound 8 was elucidated on the basis of its physical and spectroscopic data, including extensive 1D- and 2D-NMR analysis.

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A new species, Pandanus ankaranensis Callm. & Laivao (Pandanaceae), is described from the karst region of Ankarana in northern Madagascar. It resembles P.

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Investigation of the Madagascan endemic plant Ambavia gerrardii for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of the three new alkaloids 8-hydroxyeupolauridine (1), 9-methoxyeupolauridine 1-oxide (2), and 11-methoxysampangine (3) and the three known alkaloids 4-6. The structures of 1 and 2 were confirmed by synthesis. Compounds 3, 4, and 6 showed moderate to good antiproliferative activities, with IC50 values of 10.

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A recent review of Bignoniaceae for the "Catalogue of the vascular plants of Madagascar" has revealed new species in most of the genera present on the island. We provide descriptions of four new species in the genus Ophiocolea H. Perrier, a genus that is endemic to the Malagasy region: Ophiocolea ambrensis Callm.

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Investigation of the endemic Malagasy plant Bussea sakalava for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of the four new diphenylpropanes 1-4 and the new cycloheptadibenzofuran 5; compound 5 has a previously unreported natural product skeleton. The structure elucidation of these compounds was based on the analysis of their 1D and 2D NMR and mass spectroscopic data. Compounds 1-5 were tested for antiproliferative activity against the A2780 human ovarian cancer cell line.

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