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See detailAlkaloids from the stem bark of Strychnos icaja
Tchinda Tiabou, Alembert ULg; Tamze, Victorine; Ngono, Annie R N et al

in Phytochemistry Letters (2012), 5(1), 108-113

A comprehensive phytochemical study of the stem bark of Strychnos icaja was done for the first time and led to the isolation of two new monoindole alkaloids 15-hydroxyvomicine (1) and 12-methoxyicajine (2 ... [more ▼]

A comprehensive phytochemical study of the stem bark of Strychnos icaja was done for the first time and led to the isolation of two new monoindole alkaloids 15-hydroxyvomicine (1) and 12-methoxyicajine (2) along with 13 known alkaloids: the monoindoles N-methyl-sec-iso-pseudostrychnine (3), vomicine (4), icajine (5), 19,20-α-epoxy-12-methoxyicajine (6), 19,20-α-epoxy-12,15-dihydroxy-11-methoxyicajine (7), 19,20-α-epoxy-15-hydroxynovacine (8), 15-hydroxyicajine (9), 12-hydroxystrychnine (10), strychnine (11) and the tertiary bisindoles sungucine (12), isosungucine (13), strychnogucine C (14) and bisnordihydrotoxiferine (15). Apart from 10 and 11, the other alkaloids were isolated for the first time from the stem bark of this plant. The hemisynthetic derivative, Nb-chloromethosungucine (16) and the previously reported synthetic compound 3 were isolated from a natural source for the first time. Fractions and some isolated compounds were tested against the chloroquine-sensitive 3D7 strain of Plasmodium falciparum. The bisindole alkaloids were most active with IC50 ranging from 0.72 to 3.41 μg/ml whilst the monomers 1 and 3 were slightly active (IC50 39.92 and 40.27 μg/ml respectively) and 6 inactive. The structures of the compounds were determined based on the analysis of their spectral data. The full 1H and 13C NMR data of compounds 3, 6 and 7 are also reported in the present work for the first time. [less ▲]

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See detailLC–SPE–NMR–MS analysis of Strychnos usambarensis fruits from Rwanda
Cao, Martine ULg; Muganga, Raymond; Nistor, Iolanda ULg et al

in Phytochemistry Letters (2012), 5(0), 170-173

The novelty of the present work lies in the characterization of akagerine and palicoside in Strychnos usambarensis fruits by a hyphenated analytical method combining high-performance liquid chromatography ... [more ▼]

The novelty of the present work lies in the characterization of akagerine and palicoside in Strychnos usambarensis fruits by a hyphenated analytical method combining high-performance liquid chromatography coupled with solid-phase extraction (SPE), mass spectrometry (HPLC–MS) and NMR spectroscopy. Akagerine was already known in S. usambarensis roots but palicoside is described for the first time in the species. [less ▲]

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See detailAntiplasmodial Alkaloids from the Stem Bark of Strychnos malacoclados.
Tchinda Tiabou, Alembert ULg; Ngono, A. R.; Tamze, V. et al

in Planta Medica (2012), 78

From the stem bark of STRYCHNOS MALACOCLADOS, one new bisindole alkaloid, 3-hydroxylongicaudatine Y ( 1), was isolated along with the known alkaloids vomicine ( 2), bisnordihydrotoxiferine ( 3), divarine ... [more ▼]

From the stem bark of STRYCHNOS MALACOCLADOS, one new bisindole alkaloid, 3-hydroxylongicaudatine Y ( 1), was isolated along with the known alkaloids vomicine ( 2), bisnordihydrotoxiferine ( 3), divarine ( 4), longicaudatine ( 5), longicaudatine Y ( 6), and longicaudatine F ( 7). All the compounds were tested for their antimalarial activity against the chloroquine-sensitive 3D7 and -resistant W2 strains of PLASMODIUM FALCIPARUM. Longicaudatine was the most active compound with IC (50) values of 0.682 and 0.573 microM, respectively. The activity of compounds 1, 3, 4, 6, and 7 against the two strains ranged from 1.191 to 6.220 microM and 0.573 to 21.848 microM, respectively. Vomicine ( 2), the only monomer isolated, was inactive. The alkaloids of the longicaudatine-type ( 1, 5- 7) were more active than those of the caracurine-type ( 3- 4). The presence of the ether bridge in the molecule seems to increase the antiplasmodial activity. Compounds 1, 5, and 7 were tested against the WI-38 human fibroblast cell line. Longicaudatine was the most cytotoxic compound with an IC (50) of 2.721 microM. Longicaudatine F was 40-46 times more active against the two strains of P. FALCIPARUM than against the human fibroblasts and was thus considered as the more selective alkaloid. The structures of the compounds were determined based on the analysis of their spectral data. [less ▲]

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See detail17-O-Actetyl-10-hydroxycorynantheol, a selective antiplasmodial alkaloid isolated from Strychnos usambarensis leaves
Cao, Martine ULg; Muganga, Raymond ULg; Tits, Monique ULg et al

Conference (2011, December 13)

In the course of our investigations on Strychnos usambarensis leaves in order to isolate isostrychnopentamine, the main alkaloid responsible for the antiplasmodial activity of the plant, a new tertiary ... [more ▼]

In the course of our investigations on Strychnos usambarensis leaves in order to isolate isostrychnopentamine, the main alkaloid responsible for the antiplasmodial activity of the plant, a new tertiary indolic alkaloid has been isolated: 17-O-acetyl, 10-hydroxycorynantheol 1. Its structure was determined by means of spectroscopic and spectrometric methods such as UV, IR, CD, NMR and ESI-MS. 17-O-acetyl, 10-hydroxycorynantheol 1 is one of the most active monomeric indole alkaloid known to date showing an in vitro activity against Plasmodium falciparum close to 5 µM and a high selectivity. [less ▲]

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See detail17-O-Acetyl,10-hydroxycorynantheol, a Selective Antiplasmodial Alkaloid Isolated from Strychnos usambarensis Leaves
Cao, Martine ULg; Muganga, Raymond ULg; Tits, Monique ULg et al

in Planta Medica (2011), 77

In the course of our investigations on Strychnos usambarensis leaves in order to isolate isostrychnopentamine, the main alkaloid responsible for the antiplasmodial activity of the plant, a new tertiary ... [more ▼]

In the course of our investigations on Strychnos usambarensis leaves in order to isolate isostrychnopentamine, the main alkaloid responsible for the antiplasmodial activity of the plant, a new tertiary indolic alkaloid has been isolated: 17-O-acetyl, 10-hydroxycorynantheol 1. Its structure was determined by means of spectroscopic and spectrometric methods such as UV, IR, CD, NMR and ESI-MS. 17-O-acetyl, 10-hydroxycorynantheol 1 is one of the most active monomeric indole alkaloid known to date showing an in vitro activity against Plasmodium falciparum close to 5 µM and a high selectivity. [less ▲]

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See detail17-O-acetyl, 10-hydroxycorynantheol, a selective antiplasmodial alkaloid isolated from Strychnos usambarensis leaves
Cao, Martine ULg; Muganga, Raymond ULg; Tits, Monique ULg et al

Conference (2011, May 13)

In the course of our investigations on Strychnos usambarensis leaves in order to isolate isostrychnopentamine, the main alkaloid responsible for the antiplasmodial activity of the plant, a new tertiary ... [more ▼]

In the course of our investigations on Strychnos usambarensis leaves in order to isolate isostrychnopentamine, the main alkaloid responsible for the antiplasmodial activity of the plant, a new tertiary indolic alkaloid has been isolated: 17-O-acetyl, 10-hydroxycorynantheol 1. Its structure was determined by means of spectroscopic and spectrometric methods such as UV, IR, CD, NMR and ESI-MS. 17-O-acetyl, 10-hydroxycorynantheol 1 is one of the most active monomeric indole alkaloid known to date showing an in vitro activity against Plasmodium falciparum close to 5 µM and a high selectivity. [less ▲]

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See detailApplication of a new optimization strategy for the separation of tertiary alkaloids extracted from Strychnos usambarensis leaves
Nistor, Iolanda ULg; Cao, Martine ULg; Debrus, Benjamin ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2011), 56

The HPLC separation of six alkaloids extracted from Strychnos usambarensis leaves has been developed and optimized by means of a powerful methodology for modelling chromatographic responses, based on ... [more ▼]

The HPLC separation of six alkaloids extracted from Strychnos usambarensis leaves has been developed and optimized by means of a powerful methodology for modelling chromatographic responses, based on three steps, i.e. design of experiments (DoE), independent component analysis (ICA) and design space (DS). This study was the first application of a new optimization strategy to a complex natural matrix. The compounds separated are the isomers isostrychnopentamine and strychnopentamine, 10-hydroxyusambarine and 11-hydroxyusambarine, also strychnophylline and strychnofoline. Three LC parameters have been optimized using a multifactorial design comprising 29 experiments that includes 2 center point replicates. The parameters were the percentage of organic modifiers used at the beginning of a gradient profile which consisted in different proportions of methanol (MeOH) and acetonitrile (MeCN), the gradient time to reach 70% of organic modifiers starting from the initial percentage and the percentage of MeCN found in the mobile phase. Subsequent to the experimental design application, predictive multilinear models were developed and used in order to provide optimal analytical conditions. The optimum assay conditions were: methanol/acetonitrile-sodium pentane sulfonate (pH 2.2; 7.5 mM) (33.4:66.6, v/v) at a mobile phase flow rate of 1mL/min during a 40.6 minutes gradient time. The initial organic phase contained 3.7% MeCN and 96.3% MeOH. The method showed good agreement between the experimental data and predictive value throughout the studied parameters space. Improvement of the analysis time and optimized separation for the compounds of interest was possible due to the original and powerful tools applied. Finally, this study permitted the acquisition of isomers profiles allowing the identification of the optimal collecting period of Strychnos usambarensis. [less ▲]

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See detailLC-SPE-NMR-MS analysis of Strychnos usambarensis fruits from Rwanda
Cao, Martine ULg; Tits, Monique ULg; Muganga, Raymond et al

in Planta Medica (2010, September), 76(12), 1241-1242

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See detailIsostrychnopentamine, an Indolomonoterpenic Alkaloid from Strychnos usambarensis, with Potential Antitumor Activity against Apoptosis-Resistant Cancer Cells
Balde, El-Hadj Saidou; Mégalizzi, Véronique; Angenot, Luc ULg et al

in International Journal of Oncology (2010), 36

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See detailMetabolomic investigation of the ethnopharmacological use of Artemisia afra with NMR Spectroscopy and Multivariate Data Analysis.
Liu, N. Q.; Cao, Martine ULg; Frederich, Michel ULg et al

in Journal of Ethnopharmacology (2010), 128

Ethnopharmacological relevance: Artemisia afra has been used as an infusion to treat malaria throughout the southern parts of Africa, in much the same way as the antimalarial plant Artemisia annua in ... [more ▼]

Ethnopharmacological relevance: Artemisia afra has been used as an infusion to treat malaria throughout the southern parts of Africa, in much the same way as the antimalarial plant Artemisia annua in China. The antiplasmodial activity of purified components from an apolar fraction of A. afra has been shown in the past. No data on the efficacy of the tea infusion prepared from A. afra are however available. OBJECTIVE: To investigate the antiplasmodial activity of various extracts of A. afra including an ethnopharmacological prepared sample. To identify polar metabolites in A. afra and A. annua and by using multivariate data analysis investigate the metabolic differences between these species. Materials and methods: The antiplasmodial activity of A. afra and A. annua extracts were tested for activity against Plasmodiam falciparum 3D7 (chloroquine-sensitive strain) with chloroquine, quinine and artemisinin as positive controls. Hydrophilic metabolites in A. afra and A. annua were identified directly from the crude extracts through 1D- and 2D-NMR spectra. The NMR spectra were also used to differentiate between the two species using principal component analysis (PCA) for quality control purposes. RESULTS: The apolar fractions of both A. afra and A. annua showed activity against P. falciparum while activity was only found in the tea infusion of A. annua. Metabolomic studies using 1D- and 2D-NMR spectroscopy identified 24 semi-polar components in A. afra including three new phenylpropanoids for this species: caffeic acid, chlorogenic acid and 3,5-dicaffeoyl quinic acid. PCA analysis conducted on the samples yielded good separation between the polar extracts of A. afra and A. annua. CONCLUSION: These findings shows that there are no in vitro activity in the tea infusion of A. afra and lists the identified metabolites causing the metabolic differences between A. afra and A. annua for quality control purposes. [less ▲]

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See detailScreening of medicinal plants from Reunion Island for antimalarial and cytotoxic activity.
Jonville, Marie ULg; Kodja, H.; Humeau, L. et al

in Journal of Ethnopharmacology (2008), 120(3), 382-6

AIM OF THE STUDY: Nine plants from Reunion Island, selected using ethnopharmacology and chemotaxonomy, were investigated for their potential antimalarial value. MATERIALS AND METHODS: Thirty-eight ... [more ▼]

AIM OF THE STUDY: Nine plants from Reunion Island, selected using ethnopharmacology and chemotaxonomy, were investigated for their potential antimalarial value. MATERIALS AND METHODS: Thirty-eight extracts were prepared by maceration using CH(2)Cl(2) and MeOH, and were tested for in vitro activity against the 3D7 and W2 strain of Plasmodium falciparum. The most active extracts were then tested for in vitro cytotoxicity on human WI-38 fibroblasts to determine the selectivity index. Those extracts were also investigated in vivo against Plasmodium berghei infected mice. RESULTS: Most active of the extracts tested were the dichloromethane leaves extracts of Nuxia verticillata Lam. (Buddlejaceae), Psiadia arguta Voigt. (Asteraceae), Lantana camara L. (Verbenaceae), the methanol extracts from Aphloia theiformis (Vahl) Benn. (Aphloiaceae) bark, and Terminalia bentzoe L. (Combretaceae) leaves displaying in vitro IC(50) values ranging from 5.7 to 14.1mug/ml. Extracts from Psiadia, Aphloia at 200mg/(kgday) and Teminalia at 50mg/(kgday) also exhibited significant (p<0.0005) parasite inhibition in mice: 75.5%, 65.6% and 83.5%, respectively. CONCLUSION: Two plants showed interesting antimalarial activity with good selectivity: Aphloia theiformis and Terminalia bentzoe. Nuxia verticillata still needs to be tested in vivo, with a new batch of plant material. [less ▲]

Detailed reference viewed: 76 (17 ULg)