References of "Frederich, Michel"
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See detailDiscovery of a natural thiamine adenine nucleotide
Bettendorff, Lucien ULg; Wirtzfeld, Barbara; Makarchikov, Alexander F et al

in Nature Chemical Biology (2007), 3(4), 211-212

Several important cofactors are adenine nucleotides with a vitamin as the catalytic moiety. Here, we report the discovery of the first adenine nucleotide containing vitamin B1: adenosine thiamine ... [more ▼]

Several important cofactors are adenine nucleotides with a vitamin as the catalytic moiety. Here, we report the discovery of the first adenine nucleotide containing vitamin B1: adenosine thiamine triphosphate (AThTP, 1), or thiaminylated ATP. We discovered AThTP in Escherichia coli and found that it accumulates specifically in response to carbon starvation, thereby acting as a signal rather than a cofactor. We detected smaller amounts in yeast and in plant and animal tissues. [less ▲]

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See detailNematocidal compounds from the seeds of Balanites aegyptiaca isolation and structure elucidation.
Gnoula, C.; Guissou, P.; Duez, P. et al

in International Journal of Pharmacology (2007), 3(3), 280-284

A study was conducted to characterize the anthelmintic activity and to isolate the main nematocidal agent of B. aegyptiaca plant. The anthelmintic activity was evaluated in vitro by means of an original ... [more ▼]

A study was conducted to characterize the anthelmintic activity and to isolate the main nematocidal agent of B. aegyptiaca plant. The anthelmintic activity was evaluated in vitro by means of an original anthelmintic assay using Caenorhabditis elegans as a biological model. Fluorescence microscopy was used for the determination of the percentage of worm death. The structure elucidation was based on NMR, mass spectroscopic analysis and chemical methods. A bioassay-directed fractionation of the aqueous extract of B. aegyptiaca led to the isolation of balanitin-7 (also named diosgenin 3beta-O-beta-D-xylopyranosyl-(1->3)-beta-D-glucopyranosyl-(1->4)-[alpha- L-rhamnopyranosyl-(1->2)]-beta-D-glucopyranoside), as being the principal nematicidal agent. These data indicate that balanitin-7 has an appreciable nematocidal activity, which is not mediated by inducing an anti-acetylcholinesterase activity. [less ▲]

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See detailPotentialités antipaludiques des alcaloïdes indoliques
Frederich, Michel ULg; Philippe, Geneviève ULg; Tits, Monique ULg et al

in Actualités de Chimie Thérapeutique (2007), 33

This paper will be mainly illustrated with references to selected antiplasmodial compounds:- indole alkaloid analogues of emetine isolated from Strychnos usambarensis and Pogonopus tubulosus-other ... [more ▼]

This paper will be mainly illustrated with references to selected antiplasmodial compounds:- indole alkaloid analogues of emetine isolated from Strychnos usambarensis and Pogonopus tubulosus-other bisindole alkaloids isolated from Loganiacea and Apocynaceae -indoloquinolines (cryptolepine and analogues) -indolo quinazoline-6,12-diones and derivatives from Strobilanthes and other sources -aminopolycyclic beta-carbolines ( manzamines) !solated from Indo-Pacific sponges. The paper will be finally also focused on the design of chemosensitizers that are capable of reversing in vitro chloroquine resistance( case of some mono-indole alkaloids). [less ▲]

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See detailValidation of a high-performance thin-layer chromatography/densitometry method for the quantitative determination of glucosamine in a herbal dietary supplement
Esters, Virginie ULg; Angenot, Luc ULg; Brandt, V. et al

in Journal of Chromatography. A (2006), 1112(1-2), 156-164

A quantitative densitometric high-performance thin-layer chromatography (HPTLC) method was developed for the determination of glucosamine in a dietary supplement containing dried extracts of the main ... [more ▼]

A quantitative densitometric high-performance thin-layer chromatography (HPTLC) method was developed for the determination of glucosamine in a dietary supplement containing dried extracts of the main plants traditionally used for rheumatic disorders. The HPTLC method was chosen in order to circumvent the tedious and time-consuming sample preparation steps necessarily performed before using HPLC methods when analysing complex matrixes. Glucosamine was separated from the plant extracts on a silica gel 60 F(254) HPTLC plate using a saturated mixture of 2-propanol-ethyl acetate-ammonia solution (8%) (10:10:10, v/v/v). The plates were developed vertically up to a distance of 80 mm. For visualization, the plate was dipped into a modified anisaldehyde reagent and heated at 120 degrees C for 30 min in a drying oven. Glucosamine appeared as brownish-red chromatographic zones on a colourless background. Densitometric quantification was performed at lambda = 415 nm by reflectance scanning. The HPTLC method was successfully validated by applying the novel validation protocol proposed by a commission of the "Societe Francaise des Sciences et Techniques Pharmaceutiques" (SFSTP). In the pre-validation phase, the appropriate response function was determined, while in the validation phase the method showed good performance thereby fulfilling its objective of quantifying accurately. The relative standard deviations for repeatability and intermediate precision were between 4.9 and 8.6%. Moreover, the method was found to be accurate, as the two-sided 95% beta-expectation tolerance interval did not exceed the acceptance limits of 85 and 115% on the whole analytical range (800-1,200 ng of glucosamine). [less ▲]

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See detailScreening of 14 alkaloids isolated from Haplophyllum A. Juss. for their cytotoxic properties
Jansen, Olivia ULg; Akhmedjanova, Valentina; Angenot, Luc ULg et al

in Journal of Ethnopharmacology (2006), 105(1-2), 241-245

Further to a systematic chemotaxonomic study of Uzbek Haplophyllum A. Juss. plants selected on ethnopharmacological data, 14 alkaloids were screened for their cytotoxic properties. As a first selection ... [more ▼]

Further to a systematic chemotaxonomic study of Uzbek Haplophyllum A. Juss. plants selected on ethnopharmacological data, 14 alkaloids were screened for their cytotoxic properties. As a first selection for interesting compounds, each alkaloid was tested against two human cancer cell lines (HeLa and HCT-116), using WST-1 reagent. Of the 14 alkaloids, 5 were cytotoxic when tested against the HeLa line with an IC50 < 100 microM. These five compounds consisted of three furoquinolines: skimmianine; haplopine and gamma-fagarine and two pyranoquinolones: flindersine and haplamine. Only haplamine was active against the HCT-116 line. The cytotoxic properties of these five alkaloids were further investigated against five additional human cancer cell lines. Their structure-activity relationships will be discussed. Of these five pre-selected alkaloids, only haplamine showed significant cytotoxic activity against all the tested cell lines. This is the first report of the cytotoxic activity of haplamine. Finally, this pyranoquinolone alkaloid was tested here against 14 different cancer cell lines and against normal skin fibroblasts. [less ▲]

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See detailApplication of NMR to Identification of Metabolites
Frederich, Michel ULg

Scientific conference (2006, April 07)

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See detailFive labdane diterpenoids from the seeds of Aframomum zambesiacum
Kenmogne, Marguerite; Prost, Elise; Harakat, Dominique et al

in Phytochemistry (2006), 67(5), 433-438

Five labdane diterpenoids, (3-5), zambesiacolactone A (7) and zambesiacolactone B (8), were isolated from the seeds of Aframomum zambesiacum (Baker) K. Schum., along with five known labdanes and a linear ... [more ▼]

Five labdane diterpenoids, (3-5), zambesiacolactone A (7) and zambesiacolactone B (8), were isolated from the seeds of Aframomum zambesiacum (Baker) K. Schum., along with five known labdanes and a linear sesquiterpene, nerolidol. Their structures were elucidated by spectroscopic analysis. Their antiplasmodial activity was evaluated in vitro against Plasmodium falciparum. Compound 3 was the most active with an IC50 value of 4.97 mu M. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

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See detailStudy of the interaction of antiplasmodial strychnine derivatives with the glycine receptor
Philippe, Geneviève ULg; Nguyen, Laurent ULg; Angenot, Luc ULg et al

in European Journal of Pharmacology (2006), 530(1-2), 15-22

Strychnos icaja Baill. (Loganiaccae) is a liana found in Central Africa known to be an arrow and ordeal poison but also used by traditional medicine to treat malaria. Recently, many dimeric or trimeric ... [more ▼]

Strychnos icaja Baill. (Loganiaccae) is a liana found in Central Africa known to be an arrow and ordeal poison but also used by traditional medicine to treat malaria. Recently, many dimeric or trimeric indolomonoterpenic alkaloids with antiplasmodial properties have been isolated from its rootbark. Since these alkaloids are derivatives of strychnine, it was important, in view of their potential use as antimalarial drugs, to assess their possible convulsant strychnine-like properties. In that regard, their interaction with the strychnine-sensitive glycine receptor was investigated by whole-cell patch-clamp recordings on glycine-gated currents in mouse spinal cord neurons in culture and by [H-3]strychnine competition assays on membranes from adult rat spinal cord. These experiments were carried out on sungucine (leading compound of the chemical class) and on the antiplasmodial strychnogucine B (dimeric) and strychnohexamine (trimeric). In comparison with strychnine, all compounds interact with a very poor efficacy and only at concentrations > I mu M with both [H-3]strychnine binding and glycine-gated currents. Furthermore, the effects of strychnine and protostrychnine, a monomeric alkaloid (without antiplasmodial activity) also isolated from S. icaja and differing from strychnine only by a cycle opening, were compared in the same way. The weak interaction of protostrychnine confirms the importance of the G cycle ring structure in strychnine for its binding to the glycine receptor and its antagonist properties. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailExtraction and fractionation of cytotoxic metabolites from Galanthus lagodechianus Kem.-Nath
Jokhadze, Malkhaz; Kutchukhidze, J.; Murtazashvilia, T. et al

in Allergology and Immunology (Moscou) (2006), 7

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See detailBiologically active bisbenzylisoquinoline alkaloids from the root bark of Epinetrum villosum
Otshudi, A. L.; Apers, S.; Pieters, L. et al

in Journal of Ethnopharmacology (2005), 102(1), 89-94

Methanol and water extracts of the root of Epinetrum villosum (Exell) Troupin (Menispermaceae) were found to exhibit antimicrobial and antiplasmodial activities. Investigation of the active methanol ... [more ▼]

Methanol and water extracts of the root of Epinetrum villosum (Exell) Troupin (Menispermaceae) were found to exhibit antimicrobial and antiplasmodial activities. Investigation of the active methanol fraction led to the isolation of four bisbenzylisoquinoline alkaloids, i.e., cycleanine, cycleanine N-oxide, isochondodendrine and cocsoline. Structures were established by spectroscopic methods. Cocsoline displayed antibacterial and antifungal activities (MIC values of 1000-15.62 and 31.25 mu g/ml, respectively). Isochondodendrine was found to have the most potent antiplasmodial activity (IC50 = 0- 10 mu g/ml), whereas the IC50 on HCT-116 human colon carcinoma cells was 17.5 mu g/ml (selectivity index 175). Cycleanine acted against HIV-2 (EC50 = 1.83 mu g/ml) but was at least 10-fold less active against HIV-1. Cycleanine N-oxide showed no activity towards all tested microorganisms. (C) 2005 Elsevier Ireland Ltd. All rights reserved. [less ▲]

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See detailIn vitro screening of some Strychnos species for antiplasmodial activity
Philippe, Geneviève ULg; Angenot, Luc ULg; De Mol, Patrick ULg et al

in Journal of Ethnopharmacology (2005), 97(3), 535-539

The antiplasmodial activity of crude extracts of 19 species of Strychnos (Loganiaceae) was assessed in vitro against a chloroquine-susceptible strain of Plasmodium falciparum. For each species, ethyl ... [more ▼]

The antiplasmodial activity of crude extracts of 19 species of Strychnos (Loganiaceae) was assessed in vitro against a chloroquine-susceptible strain of Plasmodium falciparum. For each species, ethyl acetate (EtOAc) extracts were analysed and, for the most active species, methanolic (MeOH) extracts were also tested. Among them, Strychnos variabilis De Wild. seemed to be very promising (inhibitory concentration 50% (IC50) < 5 microg/ml) whereas two other species, Strychnos gossweileri Exell and Strychnos mellodora S. Moore, could be interesting (IC50 < 15 microg/ml) in further antimalarial studies. [less ▲]

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