Showing papers in "Natural Product Letters in 1995"
TL;DR: With the advent of Electrospray HPLC/MS instruments and a database like NAPRALERT, a quick and easy method for the dereplication of natural products can now be achieved.
Abstract: With the advent of Electrospray HPLC/MS instruments and a database like NAPRALERT, a quick and easy method for the dereplication of natural products can now be achieved.
58 citations
TL;DR: Bioassay-directed fractionation of a Toddalia asiatica (Rutaceae) extract concentrated anti-HIV activity into fractions rich in quaternary alkaloids identified nitidine, a benzo[c]phenanthridine alkaloid, and magnoflorine, an aporphinoid alkaloidal, have been isolated and identified.
Abstract: Bioassay-directed fractionation of a Toddalia asiatica (Rutaceae) extract concentrated anti-HIV activity into fractions rich in quaternary alkaloids. Nitidine (1), a benzo[c]phenanthridine alkaloid, and magnoflorine (2), an aporphinoid alkaloid, have been isolated and identified from these fractions. In an in vitro XTT-based anti-HIV assay, 1-10 μ/ml nitidine (1) inhibited human lymphoblastoid cell killing by HIV-1.
56 citations
TL;DR: In preliminary in vitro assays, all of the four new phytoalexins have shown inhibitory activity on the growth of the germinative tube of Fusarium oxysporum f.
Abstract: Four new phenalenone-type phytoalexins (2–5) have been isolated from rhizomes of Musa acuminata (AAA) infected with the fungus Fusarium oxysporum. The structures of the new phytoalexins were elucidated using spectroscopic evidence, chemical correlation, synthesis, and X-ray diffraction analysis. The major compound 2, has been previously described as a natural product, named anigorufone, but never as a phytoalexia. The chemical shift for all of the hydrogen and carbon atoms in the substances were unambiguously established by mono- and bidimensional, homo- and heteronuclear NMR experiments (1HNMR, 13CNMR, COSY, HMQC and HMBC). In preliminary in vitro assays, all of the four new phytoalexins have shown inhibitory activity on the growth of the germinative tube of Fusarium oxysporum f. sp. cubense race 4.
34 citations
TL;DR: Three new azaphilones, bulgarialactone A, B and C, were isolated from both the mycelia and fruit bodies of the Ascomycete Bulgaria inquinans and inhibit the binding of 3H-SCH 23390 to the dopamine D1 receptor.
Abstract: Three new azaphilones, bulgarialactone A (1), B (2) and C (3), were isolated from both the mycelia and fruit bodies of the Ascomycete Bulgaria inquinans. Bulgarialactone A (1) and B (2) possess antimicrobial, cytotoxic and nematicidal activities, and inhibit the binding of 3H-SCH 23390 to the dopamine D1 receptor. The isolation, structure determination and biological activities of the bulgarialactones are reported.
33 citations
TL;DR: An antifungal sordaricin derivative containing a tricyclic uronic acid moiety was isolated from the culture fluids of a wood-inhabiting Xylaria species and the structure determination and biological activities of the metabolite are described.
Abstract: An antifungal sordaricin derivative containing a tricyclic uronic acid moiety was isolated from the culture fluids of a wood-inhabiting Xylaria species. The isolation, structure determination and biological activities of the metabolite is described.
33 citations
TL;DR: The origin of all 19 carbon atoms of the phenyl-phenalenones was established by 13C NMR analysis of hydroxyanigorufone, isolated from cultured roots of Anigozanthos preissii after administration of 13C labelled precursors as mentioned in this paper.
Abstract: The biosynthetic origin of all 19 carbon atoms of the phenyl-phenalenones was established by 13C NMR analysis of hydroxyanigorufone, isolated from cultured roots of Anigozanthos preissii after administration of 13C labelled precursors. High incorporation of C-2 of [2-13C]acetate into the central carbon atom for the first time unambiguously proved the origin of this C1 unit of phenylphenalenones.
31 citations
TL;DR: In this article, the potent flavour compound 2-acetyl-1-pyrroline (1) was identified for the first time in wines spoiled by mousy taint.
Abstract: The potent flavour compound 2-acetyl-1-pyrroline (1) was identified for the first time in wines spoiled by mousy taint. Identification was verified by comparison of GC and GC-MS data with those of authentic reference material. GC-SNEFF analysis of (1) further confirmed its intense mousy aroma.
30 citations
TL;DR: Reinvestigation of the ascidian Didemnum sp.
Abstract: Reinvestigation of the ascidian Didemnum sp from Palau revealed that the previously reported metabolites, didemnaketals A (1) and B (2), are artifacts formed as a result of prolonged storage of the ascidian in methanol Fresh extracts gave a single terpenoid, didemnaketal C (3), which on methanolysis yielded didemnaketal B (2)
30 citations
TL;DR: In this paper, two benzylisoquinoline and four aporphine alkaloids were isolated from roots of an oceanic Annonaceae, Xylopia papuana.
Abstract: Two benzylisoquinoline and four aporphine alkaloids were isolated from roots of an oceanic Annonaceae, Xylopia papuana. The benzylisoquinoline alkaloids displayed a selectivity for dopamine receptors whereas aporphine alkaloids, specially anonaine, inhibited selectively dopamine uptake.
29 citations
TL;DR: In this article, three new biaryl ethers have been isolated from the endophytic fungus Phomopsis sp‥ and used to synthesize a biaryl derivative for the fungus.
Abstract: Phomosines A-C, three new biaryl ethers have been isolated from the endophytic fungus Phomopsis sp‥
26 citations
TL;DR: From the roots of Dichapetalum madagascariense, a plant constituent with a new basic skeleton, dichapetalin A has been isolated by spectroscopic methods as discussed by the authors.
Abstract: From the roots of Dichapetalum madagascariense (Dichapetalaceae) dichapetalin A, a plant constituent with a new basic skeleton, has been isolated. Its structure was elucidated by spectroscopic methods. In-vitro experiments revealed a strong and selective cytotoxicity.
TL;DR: Bioassay-directed fractionation of an extract from the fungus Nigrospora sphaerica yielded a new 14-membered lactone, named nigrosporolide, whose structure was established by spectroscopic techniques.
Abstract: Bioassay-directed fractionation of an extract from the fungus Nigrospora sphaerica (strain UK181RRC) yielded a new 14-membered lactone, named nigrosporolide, whose structure was established by spectroscopic techniques. This compound inhibited the growth of etiolated wheat coleoptiles.
TL;DR: In this paper, the MeOH extract from the stem bark of Goniothalamus arvensis (Annonaceae) led to the isolation of a new styryl-lactone, (+)-goniotharvensin (1), and two other known styrylslactones: (+)-altholactone (2 ) and (+)-isoaltholase (3 ).
Abstract: The fractionation of the MeOH extract from the stem bark of Goniothalamus arvensis (Annonaceae) led to the isolation of a new styryl-lactone, (+)-goniotharvensin ( 1 ), and two other known styryl-lactones: (+)-altholactone ( 2 ) and (+)-isoaltholactone ( 3 ). Goniotharvensin ( 1 ), is a tetrahydrofurano-5-pyrone whose structure was established on the basis of MS and NMR experiments as well as chemical derivatization.
TL;DR: In this article, three monoterpene indole alkaloids, 16-hydroxymethyl-pleiocarpamine 2, 16epi-deacetylakuammiline 4 and 14α-hydroxycondylocarpine 8, have been isolated from the stem bark of Kopsia deverrei (Apocynaceae).
Abstract: Three new monoterpene indole alkaloids, 16-hydroxymethyl-pleiocarpamine 2, 16-epi-deacetylakuammiline 4 and 14α-hydroxycondylocarpine 8, have been isolated from the stem bark of Kopsia deverrei (Apocynaceae). The proposed structures were assigned after detailed analysis of their 1H and 13C NMR spectra and by chemical correlation.
TL;DR: The configuration at C-18 of variabilin (1), isolated from a Caribbean sponge, Ircinia felix, was established to be R. The occurrence of (18R)-variabilin was demonstrated for the first time, whereas its (18S)-antipode were reported previously as discussed by the authors.
Abstract: The configuration at C-18 of variabilin (1), isolated from a Caribbean sponge, Ircinia felix, was established to be R. Variabilin acetate (2) was oxidatively degraded and converted into di-(R)-MTPA ester of 2-methylheptane-1,6-diol, which was found to have 2R -configuration by 1H-NMR studies in comparison with synthetic (2S, 6R S)- and (2R S, 6R S)-esters. The occurrence of (18R)-variabilin was demonstrated for the first time, whereas its (18S)-antipode were reported previously.
TL;DR: In this paper, the new phenolic triterpenes, blepharodol (5) and 7α-hydroxy-blepharodorol (6) were isolated from Maytenus blepharis and canarol (8), 7α,hydrox-canarol, 7-hydoxy-6-oxoiguesterol (11), canaradial (12), and the triterpene methylene quinones iguesteroquinone (13), and were elucidated by means of 1H and 13
Abstract: The new phenolic triterpenes, blepharodol (5) and 7α-hydroxy-blepharodol (6) were isolated from Maytenus blepharodes and canarol (8), 7α-hydroxy-canarol (9), 7-hydroxy-6-oxoiguesterol (11), canaradial (12) and the triterpene methylene quinones iguesteroquinone (13) and 7α-hydroxy-7,8-dihydro-iguesterin (14) and were isolated from Maytenus canariensis. Their structures were elucidated by means of 1H and 13C NMR spectroscopic studies, including homo and heteronuclear correlations, DEPT, COSY, HMQC and HMBC experiments. These products are intermediates in the biogenetic pathway of methylene quinone triterpenes.
TL;DR: Bioassay-guided fractionation of an extract from the marine alga Laurencia majuscula provided three brominated chamigrane sesquiterpenes that produced a novel pattern of antitumor activity against the National Cancer Institute's in vitro cell line panel.
Abstract: Bioassay-guided fractionation of an extract from the marine alga Laurencia majuscula provided three brominated chamigrane sesquiterpenes (1–3). These compounds produced a novel pattern of antitumor activity against the National Cancer Institute's in vitro cell line panel. They were cytotoxic to certain cell lines in the colon cancer subpanel at concentrations 10–100 fold lower than the mean cytotoxic concentration observed in the other tumor subpanels.
TL;DR: Four new anti-microbial, unsaturated amino alcohols were isolated as their acetyl derivatives from an extract of a South African marine ascidian to establish the structures of these compounds.
Abstract: Four new anti-microbial, unsaturated amino alcohols were isolated as their acetyl derivatives (1–4) from an extract of a South African marine ascidian (Pseudodistoma species). Standard spectroscopic methods were used to establish the structures of these compounds as 2S*-acetamido-3S*-acetoxy-5E, 13-tetradecadiene (1), 2S*-acetamido-3S*-acetoxy-5E-tetradecene (2), 1-acetamido-2-acetoxy-4E, 12-tridecadiene (3) and 1-acetamido-2-acetoxy- 4E-tridecene (4).
TL;DR: Kopsilactone and kopsone, two monoterpene alkaloids, have been isolated from Kopsia macrophylla (Apocynaceae) from Malaysia as mentioned in this paper.
Abstract: Kopsilactone and kopsone, two monoterpene alkaloids, have been isolated from Kopsia macrophylla (Apocynaceae) from Malaysia. The structure elucidation involved spectral data analysis and chemical transformations.
TL;DR: A new styrylpyrone derivative (+)-5β-hydroxygoniothalamin (1) was isolated from the stem bark of Goniothalamus dolichocarpus as discussed by the authors.
Abstract: A new styrylpyrone derivative (+)-5β-hydroxygoniothalamin (1) was isolated from the stem bark of Goniothalamus dolichocarpus. The structure and stereochemistry of (1) and its diastereoisomer (+)-5α-hydroxygoniothalamin (2) were established by NMR spectra, X-ray crystallography and partial synthesis.
TL;DR: In this paper, the synthesis of (±)-12-demethoxy-N(1)-acetylcylindrocarine was described, followed by the formal synthesis of the latter compound.
Abstract: Reaction of compound (4) with (5) give a mixture of the isomers (7) and (8) through the intermediate (1). Further conversions led through the oxo- (9), (10) and thioxo (11), (12) derivatives to (±)-19-ethoxycarbonyl-19-demethylvincadifformine (3), and (±)-18-methoxycarbonyl-D(14)-norvincadifformine (13). The preparation of the former compound constitutes the formal synthesis of (±)-12-demethoxy-N(1)-acetylcylindrocarine (2). Oxidative ring transformation of the latter gave (±)-21-methoxycarbony 1-D(18)-norapovincamine (14).
TL;DR: Three bioactive diketopiperazines were isolated from the phytopathogen fungus Fusarium oxysporum and showed the ability to reprogram the excitatory and inhibitory properties of L-prolyl-L-glycine.
Abstract: Three bioactive diketopiperazines, cyclo-(L-prolyl-L-glycine), cyclo-(L-prolyl-L-valine) and cyclo-(L-leucyl-L-proline) were isolated from the phytopathogen fungus Fusarium oxysporum.
TL;DR: In this article, the indole alkaloids of the aspidosperma type were obtained in minor amounts from the leaf extract of Tabernaemontana divaricata (double flower variety).
Abstract: Novel indole alkaloids of the aspidosperma-type were obtained in minor amounts from the leaf extract of Tabernaemontana divaricata (double flower variety). The structures of these alkaloids were elucidated by spectral methods.
TL;DR: In this paper, the total synthesis of an antifungal novel amino acid derivative, sphingofungin D (N-acetyl asperfungin) starting from myo-inositol and (R)-epoxyoctane is described.
Abstract: The total synthesis of an antifungal novel amino acid derivative, sphingofungin D (N-acetyl asperfungin) starting from myo-inositol and (R)-epoxyoctane is described. This synthetic study showed that the undetermined stereochemistry at C-14 in sphingofungins should be R.
TL;DR: Methyl ent-isocopalate, used in the synthesis of bioactive spongianes, was synthesized in four steps from labdanolic acid isolated from Cistus ladaniferus as mentioned in this paper.
Abstract: Methyl ent-isocopalate, used in the synthesis of bioactive spongianes, was synthesized in four steps from labdanolic acid isolated from Cistus ladaniferus.
TL;DR: The hybrid cells showed a greater diversity of alkaloid biosynthesis when compared with the parental cultures, and the alkaloids were identified as tubotaiwine, an isomeric mixture of vallesiachotamine, stemmadenine and vomilenine.
Abstract: The phytochemical analyses of a somatic hybrid cell suspension culture of the genus and species combination Rauwolfia serpentina x Rhazya stricta revealed a number of monoterpenoid indole alkaloids. The alkaloids were identified as tubotaiwine, an isomeric mixture of vallesiachotamine, stemmadenine and vomilenine and were all produced in small amounts < 2mg/litre cell suspension. The hybrid cells showed a greater diversity of alkaloid biosynthesis when compared with the parental cultures.
TL;DR: Indicusin (1) was isolated from CHCl3-EtOH (3:2) fraction of Hemidesmus indicus R Br. (family Asclepiadaceae) with the help of FABMS, 1H NMR, 13C NMR spectroscopy and chemical transformations.
Abstract: A novel pregnane oligoglycoside viz. Indicusin (1) was isolated from CHCl3-EtOH (3:2) fraction of Hemidesmus indicus R Br. (family Asclepiadaceae). With the help of FABMS, 1H NMR, 13C NMR spectroscopy and chemical transformations, the structure of 1 was defined as 11α, 12β-di-O-acetyl-orgogenin-3-O-β-D-cymaropyranosyl (1→4)-O-β-D-cymaropyranosyl (1→4)-O-β-D-cymaropyranoside.
TL;DR: Two novel alkaloids, 1-oxo-1,2-dihydro-12-demethyl-12hydroxyacronycine (1) and 2,3-dicarbomethoxy-1-methyl-4(1H)-quinolinone (3) have been isolated from the leaves of Sarcomelicope dogniensis as mentioned in this paper.
Abstract: Two novel alkaloids, 1-oxo-1,2-dihydro-12-demethyl-12-hydroxyacronycine (1) and 2,3-dicarbomethoxy-1-methyl-4(1H)-quinolinone (3) have been isolated from the leaves of Sarcomelicope dogniensis. The biogenesis of this latter most probably involves oxidation of the A aromatic ring of a 1,2,3,4-tetra-O-subtituted acridone, such as melicopidine.
TL;DR: In this article, a prenyl resacetophenone was synthesized in 77% yield by a para sigmropic rearrangement of 2.5′-(3,3-dimethylallyl)-4′-methoxyethoxymethyl resacetone.
Abstract: 5′-(3,3-Dimethylallyl)-4′-methoxyethoxymethyl resacetophenone has been synthesized in 77% yield by para sigmatropic rearrangement of 2′-(3,3-dimethylallyl)-4′-methoxyethoxymethyl resacetophenone. Using this newly synthesized prenyl resacetophenone precursor, the yields of preparation of the naturally occurring broussochalcones A and B have been increased by a factor of 30 and 5, respectively.
TL;DR: In this article, a methanolic extract of stinging nettle (Urtica dioica L) leaves two new β-D-glucopyranosides of diastereomeric 3-hydroxy-α-ionol[4-(4′-hydrox-2′, 6′,6′-trimethylcyclohex]-2′-en-1-yl)-but-3-en 2-ol] 1a and 2a were isolated by adsorption chromatography on XAD-2 resin and MeOH el
Abstract: From a methanolic extract of stinging nettle (Urtica dioica L.) leaves two new β-D-glucopyranosides of diastereomeric 3-hydroxy-α-ionol[4-(4′-hydroxy-2′,6′,6′-trimethylcyclohex-2′-en-1-yl)-but-3-en-2-ol] 1a and 2a were isolated by adsorption chromatography on XAD-2 resin and MeOH elution. After preseparation of the crude glycosidic extract with rotation locular countercurrent chromatography (RLCC) and multi-layer coil countercurrent chromatography (MLCCC), the new natural products were peracetylated, purified by HPLC and characterized as their penta-acetates 1b and 2b.