References of "Frederich, Michel"
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See detailIdentification and determination of alkaloids in Fumaria Species from Romania
Paltinean, Ramona; Toju, A; Wauters, Jean-Noël ULg et al

in Digest Journal of Nanomaterials & Biostructures [=DJNB] (2013), 8(2), 817-824

Four Fumaria species (F. vaillantii Loisel, F. parviflora Lam., F. rostellata Knaf and F. jankae Hausskn.) were analysed in order to determine the presence of the isoquinoline alkaloids allocryptopine ... [more ▼]

Four Fumaria species (F. vaillantii Loisel, F. parviflora Lam., F. rostellata Knaf and F. jankae Hausskn.) were analysed in order to determine the presence of the isoquinoline alkaloids allocryptopine, chelidonine, protopine, bicuculline, sanguinarine, cheleritrine, stylopine, and hydrastine through an HPLC-DAD method. Protopine and sanguinarine were present in all extracts. Bicuculline and stylopine were found in F. vaillantii and F. parviflora, whilst chelidonine was identified only in F. vaillantii and hydrastine in F. jankae, so they represent potential taxonomic markers that differentiate the four plants. The richest species in isoquinoline alkaloids was F. parviflora. Our study showed significant differences between the four Fumaria species, both qualitative and quantitative. [less ▲]

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See detailComparative morphological studies on some species of the genus Fumaria
Paltinean, Ramona; Wauters, Jean-Noël ULg; Tits, Monique ULg et al

in Farmacia (2013), 61(2), 371-377

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See detailAntiparasitic hybrids of Cinchona alkaloids and bile acids.
Leverrier, Aurelie; Bero, Joanne; Frederich, Michel ULg et al

in European journal of medicinal chemistry (2013), 66

A series of 16 hybrids of Cinchona alkaloids and bile acids (4a-h, 5a-h) was prepared by means of a Barton-Zard decarboxylation reaction. Quinine, quinidine, cinchonine and cinchonidine were ... [more ▼]

A series of 16 hybrids of Cinchona alkaloids and bile acids (4a-h, 5a-h) was prepared by means of a Barton-Zard decarboxylation reaction. Quinine, quinidine, cinchonine and cinchonidine were functionalized at position C-2 of the quinoline nucleus by radical attack of a norcholane substituent. The newly synthesized hybrids were evaluated in vitro for their antitrypanosomal, antileishmanial and antiplasmodial activities, along with their cytotoxicity against WI38, a normal human fibroblast cell line. Seven compounds (4d, 4f, 4h, 5b, 5d, 5f, 5h) showed promising trypanocidal activity with IC(5)(0) values in the same range as the commercial drug suramine. Moreover all the 16 hybrids showed antiplasmodial activity (IC(5)(0) </= 6 mug/ml), particularly those containing a nor-chenodeoxycholane moiety (4b, 4d, 4f, 4h, 5b, 5d, 5f, 5h) with IC(5)(0) values comparable to those of the natural alkaloids, and selectivity indices in the range of 5.6-15.7. [less ▲]

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See detailRevealing the anti-tumoral effect of Algerian Glaucium flavum roots against human cancer cells.
Bournine, Lamine; Bensalem, Sihem; Peixoto, Paul ULg et al

in Phytomedicine : International Journal of Phytotherapy and Phytopharmacology (2013), 20(13), 1211-1218

Glaucium flavum (G. flavum) is a plant from the Papaveraceae family native to Algeria where it is used in local traditional medicine to treat warts. G. flavum root crude alkaloid extract inhibited breast ... [more ▼]

Glaucium flavum (G. flavum) is a plant from the Papaveraceae family native to Algeria where it is used in local traditional medicine to treat warts. G. flavum root crude alkaloid extract inhibited breast cancer cell proliferation and induced G2/M phase cycle arrest and apoptosis without affecting normal cells, which is a highly awaited feature of potential anti-cancer agents. G. flavum significantly reduced growth and vascularization of human glioma tumors on chicken chorioallantoic membrane (CAM) in vivo. The chromatographic profile of the dichloromethane extract of G. flavum root showed the presence of different constituents including the isoquinoline alkaloid protopine, as the major compound. We report for the first time that G. flavum extract may represent a new promising agent for cancer chemotherapy. [less ▲]

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See detailIn vivo antimalarial activity of Keetia leucantha twigs extracts and in vitro antiplasmodial effect of their constituents.
Bero, Joanne; Herent, Marie-France; Schmeda-Hirschmann, Guillermo et al

in Journal of Ethnopharmacology (2013), 149(1), 176-83

ETHNOPHARMACOLOGICAL RELEVANCE: The West African tree Keetia leucantha (Rubiaceae) is used in traditional medicine in Benin to treat malaria. The twigs dichloromethane extract was previously shown to ... [more ▼]

ETHNOPHARMACOLOGICAL RELEVANCE: The West African tree Keetia leucantha (Rubiaceae) is used in traditional medicine in Benin to treat malaria. The twigs dichloromethane extract was previously shown to inhibit in vitro Plasmodium falciparum growth with no cytotoxicity (>100microg/ml on human normal fibroblasts). MATERIALS AND METHODS: The dichloromethane and aqueous extracts of twigs of K. leucantha were evaluated in vivo against Plasmodium berghei NK 173 by the 4-day suppressive test and in vitro against a chloroquine-sensitive strain of Plasmodium falciparum (3D7) using the measurement of the plasmodial lactate dehydrogenase activity. Bioguided fractionations were realized and compounds were structurally elucidated using extensive spectroscopic analysis. RESULTS: The in vivo antimalarial activity of K. leucantha dichloromethane and aqueous twigs extracts were assessed in mice at the dose of 200mg/kg/day. Both extracts exhibited significant effect in inhibiting parasite growth by 56.8% and 53.0% (p<0.0001) on day 7-postinfection. An LC-MS analysis and bioguided fractionations on the twigs dichloromethane extract led to the isolation and structural determination of scopoletin (1), stigmasterol (2), three phenolic compounds: vanillin (3), hydroxybenzaldehyde (4) and ferulaldehyde (5), eight triterpenic esters (6-13), oleanolic acid and ursolic acid. The antiplasmodial activity of the mixture of the eight triterpenic esters showed an antiplasmodial activity of 1.66+/-0.54microg/ml on the 3D7 strain, and the same range of activity was observed for isolated isomers mixtures. CONCLUSIONS: This is the first report on the in vivo activity of K. leucantha extracts, the isolation of thirteen compounds and analysis of their antiplasmodial activity. The results obtained may partially justify the traditional use of K. leucantha to treat malaria in Benin. [less ▲]

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See detailIs artemisinin the only antiplasmodial compound in the Artemisia annua tea infusion? An in vitro study.
Mouton, Julia; Jansen, Olivia ULg; Frederich, Michel ULg et al

in Planta Medica (2013), 79(6), 468-70

In our ongoing investigation into Artemisia annua for the treatment of malaria, we decided to study the possibility that synergism might enhance the efficacy of artemisinin. Our main objective was to test ... [more ▼]

In our ongoing investigation into Artemisia annua for the treatment of malaria, we decided to study the possibility that synergism might enhance the efficacy of artemisinin. Our main objective was to test tea infusions and nonpolar extracts prepared from different A. annua varieties against Plasmodium falciparum in vitro in order to determine if synergism will increase the effectiveness of artemisinin in the samples as compared to pure artemisinin. We found that the IC50 of artemisinin in the tea and nonpolar extracts was not significantly different to the IC50 of pure artemisinin. We could show that the year and country of harvest or storage conditions did not have any influence on the activity and that it narrowly followed the concentration of artemisinin in all the extracts. In conclusion, based on these in vitro results, artemisinin seems to be the only active antiplasmodial compound in A. annua. [less ▲]

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See detailDimeric bisindole alkaloids from the stem bark of Strychnos nux-vomica L.
Jonville, Marie-Caroline ULg; Dive, Georges ULg; Angenot, Luc ULg et al

in Phytochemistry (2013), 87

Strychnos nux-vomica L. (Loganiaceae) is famous for its monomeric alkaloid content, such as strychnine, a convulsant poison. The stem bark of the tree is traditionally used to treat intermittent fever in ... [more ▼]

Strychnos nux-vomica L. (Loganiaceae) is famous for its monomeric alkaloid content, such as strychnine, a convulsant poison. The stem bark of the tree is traditionally used to treat intermittent fever in South East Asia. In various studies, it appeared that dimeric indolo-monoterpenic alkaloids possess a promising activity on Plasmodium falciparum. Three bisindolomonoterpenic alkaloids together with strychnochrysine, previously identified in the root bark of S. nux-vomica, were isolated from the stem bark. The structures of these compounds were established using NMR spectroscopy and mass spectrometry. Stereochemistry of the compounds was confirmed by molecular modelling. This then allowed the structural determination of strychnoflavine, a coloured bisindole alkaloid previously isolated from the root bark of the tree. Moreover, the conformational inversion in alkaloids possessing an ether bond in the strychnane moiety could be easily predicted by specific δ 13C NMR values. These longicaudatine-type alkaloids were found to display in vitro antiplasmodial activity against a chloroquine resistant strain and a chloroquine sensitive strain. The most interesting was strychnochrysine showing an IC 50 value at around 10 μM. © 2012 Elsevier Ltd. All rights reserved. [less ▲]

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See detailPlantes Médicinales Antipaludiques de l'île de la Réunion
Frederich, Michel ULg; Jonville, Marie-Caroline ULg; Grondin, Isabelle et al

Conference (2012, November 06)

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See detailPotential anticancer activity of young Carpinus betulus leaves
Cieckiewicz, Ewa ULg; Angenot, Luc ULg; Gras, T et al

in Planta Medica (2012, August), 78(11), 1178

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See detailIn vivo antimalarial activity of twigs extracts from Keetia leucantha
Béro, Joanne; Frederich, Michel ULg; Quetin-Leclercq, Joëlle

in Planta Medica (2012, August), 78(11), 1188

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See detailInvestigation of African plants traditionally used to treat malaria
Frederich, Michel ULg

Conference (2012, July 05)

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See detailDEVELOPMENT AND VALIDATION OF A LC-UV METHOD FOR THE DOSAGE OF A TRACER IN AN IMPROVED TRADITIONAL MEDICINE
Tshisekedi Tshibangu, Pascal; Kalenda Dibungi T., Pascal; Wauters, Jean-Noël ULg et al

Conference (2012, July)

According to World Health Organisation, 80% of the African populations use Improved Traditional Medicines (ITM) to threat several diseases. Even if some of these ITM are nowadays registered with local ... [more ▼]

According to World Health Organisation, 80% of the African populations use Improved Traditional Medicines (ITM) to threat several diseases. Even if some of these ITM are nowadays registered with local health authorities, the knowledge of their qualitative and quantitative composition still remains a challenge for ensuring health security of populations. In this context, an analytical method using liquid chromatography technique with UV detection was developed to allow the dosage of a tracer (major compound) in an ITM (syrup containing extract plants) registered in D.R. Congo by the “Centre de Recherche en Médecine Traditionnelle Améliorée” and marketed for use against malaria. For that purpose, a simple and rapid experimental plan considering a Plackett-Burman design was applied by testing simultaneously two significant factors, temperature of analytical column (T°) and gradient time (TG) for eluting acetonitrile (ACN) from 5% to 95%, while focusing on the separation of the tracer and an adjacent unknown compound (critical peak pairs). Suitable separation (resolution of 1.5) was obtained between these latter with T° of 15°C and TG of 60 min (20% to 65% of ACN). Prior to routine use, the analytical method was validated following the total error strategy described by the SFSTP guidelines and according to the ISO norm 17025:2005. Specificity/selectivity of the method was demonstrated by the absence of interference at the retention time of the major compound comparing to the syrup matrix. Very interesting results were observed for trueness (relative biases below 0.9%), for precision (RSD mostly below 2.2% for repeatability and time-different intermediate precision), for accuracy (beta tolerance intervals below 10% of the acceptance limits) and linearity. Finally, the method was applied to quantify the major compound in several batches of syrups ITM as well as for stability studies. [less ▲]

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See detailDécouverte de substances naturelles antipaludiques et métabolomique.
Frederich, Michel ULg

Scientific conference (2012, May 16)

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See detailPotential anticancer activity of young Carpinus betulus leaves.
Cieckiewicz, Ewa ULg; Angenot, Luc ULg; Gras, T. et al

in Phytomedicine : International Journal of Phytotherapy and Phytopharmacology (2012), 19(3/4), 278-284

As part of our continuing research for anticancer compounds from the Walloon Region forest, EtOAc extract from Carpinus betulus leaves was phytochemically studied, leading to the bioguided isolation of ... [more ▼]

As part of our continuing research for anticancer compounds from the Walloon Region forest, EtOAc extract from Carpinus betulus leaves was phytochemically studied, leading to the bioguided isolation of pheophorbide a, which is responsible of anticancer properties of C. betulus young leaves. This compound was identified using nuclear magnetic resonance and mass spectrophotometric data and comparison with a commercial standard. Evaluation of the growth inhibitory activities of pheophorbide a using MTT colorimetric assay and phase-contrast microscopy in various human cancer cell lines confirmed the photoactivable properties of this compound. Our research showed, for the first time, the presence of pheophorbide a, a chlorophyll derived compound, which we quantified in high quantities in young leaves of C. betulus. This is in contrast with the literature which generally describes pheophorbide a as a catabolic product of chlorophyll, then preferentially present in old leaves. [less ▲]

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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 detailCombination of capillary electrophoresis, molecular modelling and nuclear magnetic resonance to study the interaction mechanisms between single-isomer anionic cyclodextrin derivatives and basic drug enantiomers in a methanolic background electrolyte.
Servais, Anne-Catherine ULg; Rousseau, Anne; Dive, Georges ULg et al

in Journal of Chromatography. A (2012), 1232

In order to improve our knowledge of the mechanisms of enantiomer recognition pattern in nonaqueous systems, an approach combining nonaqueous CE (NACE), molecular modelling and NMR was undertaken ... [more ▼]

In order to improve our knowledge of the mechanisms of enantiomer recognition pattern in nonaqueous systems, an approach combining nonaqueous CE (NACE), molecular modelling and NMR was undertaken. Bupivacaine and propranolol were selected as model compounds and their interactions with two single-isomer highly charged beta-CD derivatives, namely heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-CD (HDMS-beta-CD) and heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta-CD (HDAS-beta-CD), were studied. The CD-bupivacaine complexes were evaluated by 2-D Rotating-frame Overhauser Effect SpectroscopY (ROESY) experiments. From these experiments, it can be assumed that inclusion complexes are not formed, whatever the CD derivative used. Molecular modelling was performed at the RHF/MINI-1 or B3LYP/6-31G(d) level. External as well as inclusion type complexes with the alkyl chain of propranolol into both CD cavities were located. Interaction energies calculated for bupivacaine and propranolol correlated with the enantiomer migration order observed in the NACE experiments using both anionic CD derivatives. The interaction of propranolol with HDMS-beta-CD or HDAS-beta-CD gives rise to a family of external and inclusion complexes in which some are more probably obtained. [less ▲]

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See detailAnti-plasmodial activity of Dicoma tomentosa (Asteraceae) and identification of urospermal A-15- O-acetate as the main active compound.
Jansen, Olivia ULg; Tits, Monique ULg; Angenot, Luc ULg et al

in Malaria Journal (2012), 11(1), 2891-9

ABSTRACT: BACKGROUND: Natural products could play an important role in the challenge to discover new anti-malarial drugs. In a previous study, Dicoma tomentosa (Asteraceae) was selected for its promising ... [more ▼]

ABSTRACT: BACKGROUND: Natural products could play an important role in the challenge to discover new anti-malarial drugs. In a previous study, Dicoma tomentosa (Asteraceae) was selected for its promising anti-plasmodial activity after a preliminary screening of several plants traditionally used in Burkina Faso to treat malaria. The aim of the present study was to further investigate the antiplasmodial properties of this plant and to isolate the active anti-plasmodial compounds. METHODS: Eight crude extracts obtained from D. tomentosa whole plant were tested in vitro against two Plasmodium falciparum strains (3D7 and W2) using the p-LDH assay (colorimetric method). The Peters' four-days suppressive test model (Plasmodium berghei-infected mice) was used to evaluate the in vivo anti-plasmodial activity. An in vitro bioguided fractionation was undertaken on a dichloromethane extract, using preparative HPLC and TLC techniques. The identity of the pure compound was assessed using UV, MS and NMR spectroscopic analysis. In vitro cytotoxicity against WI38 human fibroblasts (WST-1 assay) and haemolytic activity were also evaluated for extracts and pure compounds in order to check selectivity. RESULTS: The best in vitro anti-plasmodial results were obtained with the dichloromethane, diethylether, ethylacetate and methanol extracts, which exhibited a high activity (IC50 [less than or equal to] 5 mug/ml). Hot water and hydroethanolic extracts also showed a good activity (IC50 [less than or equal to] 15 mug/ml), which confirmed the traditional use and the promising anti-malarial potential of the plant. The activity was also confirmed in vivo for all tested extracts. However, most of the active extracts also exhibited cytotoxic activity, but no extract was found to display any haemolytic activity. The bioguided fractionation process allowed to isolate and identify a sesquiterpene lactone (urospermal A-15-O-acetate) as the major anti-plasmodial compound of the plant (IC50 < 1 mug/ml against both 3D7 and W2 strains). This was also found to be the main cytotoxic compound (SI =3.3). While this melampolide has already been described in the plant, this paper is the first report on the biological properties of this compound. CONCLUSIONS: The present study highlighted the very promising anti-plasmodial activity of D. tomentosa and enabled to identify its main active compound, urospermal A-15-O-acetate. The high antiplasmodial activity of this compound merits further study about its anti-plasmodial mechanism of action. The active extracts of D. tomentosa, as well as urospermal A 15-Oacetate, displayed only a moderate selectivity, and further studies are needed to assess the safety of the use of the plant by the local population. [less ▲]

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See detailArdisikivuoside, a new triterpenoid saponin from Ardisia kivuensis (Mysinaceae)
Ndontsa, Blanche; Tchinda Tiabou, Alembert ULg; Teponno, Rémy et al

in Natural Product Communications [=NPC] (2012), 7

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See detailRotenoid content and in vitro acaricidal activity of Tephrosia vogelii leaf extract on the tick Rhipicephalus appendiculatus
Kalume; Losson, Bertrand ULg; Angenot, Luc ULg et al

in Veterinary Parasitology (2012), 190(1-2), 204-209

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