References of "Frederich, Michel"
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See detailFirst and second generations of COX-2 selective inhibitors
De leval, X.; Julémont, F.; Benoit, V. et al

in Mini Reviews in Medicinal Chemistry (2004), 4

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See detailNew developments on thromboxane and prostacyclin modulators. Part I: thromboxane modulators
Dogné, Jean-Michel ULg; De leval, X.; Hanson, Julien ULg et al

in Current Medicinal Chemistry (2004), 11

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See detailQuantitative analysis of strychnine and brucine in Strychnos nux-vomica using H-1-NMR
Frederich, Michel ULg; Choi, Y. H.; Verpoorte, R.

in Planta Medica (2003), 69(12), 1169-1171

A quantitative analysis using H-1-NMR (Q-NMR) has been developed for the determination of strychnine and brucine in Strychnos nux-vomica seeds and stems. The advantages of the method are that no reference ... [more ▼]

A quantitative analysis using H-1-NMR (Q-NMR) has been developed for the determination of strychnine and brucine in Strychnos nux-vomica seeds and stems. The advantages of the method are that no reference alkaloids are needed for calibration curves, the quantification could be directly realized on a crude extract, strychnine and brucine could easily be distinguished, an overall profile of the preparation (including non alkaloid compounds) could be directly obtained, and a very significant time-gain could be achieved, in comparison to conventional HPLC methods, for instance. [less ▲]

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See detailQuantification of tagitinin C in Tithonia diversifolia by reversed-phase high-performance liquid chromatography.
Goffin, Eric ULg; da Cunha, Antonio Proenca; Ziemons, Eric ULg et al

in Phytochemical Analysis [=PCA] (2003), 14(6), 378-80

A simple, rapid and reliable reversed-phase high-performance liquid chromatographic method for the determination of tagitinin C, an anti-plasmodial sesquiterpene lactone isolated from the aerial parts of ... [more ▼]

A simple, rapid and reliable reversed-phase high-performance liquid chromatographic method for the determination of tagitinin C, an anti-plasmodial sesquiterpene lactone isolated from the aerial parts of Tithonia diversifolia, has been developed. The assay has been used to quantify tagitinin C in various extracts of the aerial parts of T. diversifolia. [less ▲]

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See detailAntiplasmodial and cytotoxic alkaloids from Strychnos species
Frederich, Michel ULg

Conference (2003, March 14)

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See detailIsostrychnopentamine, an indolomonoterpenic alkaloid from Strychnos usambarensis, induces cell cycle arrest and apoptosis in human colon cancer cells
Frederich, Michel ULg; Bentires-Alj, M.; Tits, Monique ULg et al

in Journal of Pharmacology and Experimental Therapeutics (2003), 304(3), 1103-1110

Isostrychnopentamine (ISP) is an indolomonoterpenic alkaloid that is present in the leaves of Strychnos usambarensis, a well known African shrub or little tree. The roots contain quaternary alkaloids ... [more ▼]

Isostrychnopentamine (ISP) is an indolomonoterpenic alkaloid that is present in the leaves of Strychnos usambarensis, a well known African shrub or little tree. The roots contain quaternary alkaloids, which are used to make a curare-like arrow poison. However, tertiary alkaloids isolated from the same plant possess cytotoxic activities against mammalian cells and protozoa. The effect of ISP has been investigated on the growth and viability of HCT-116 colon cancer cells during their exponentially growing phase. ISP induced apoptotic cell death as shown by the translocation of phosphatidylserine from the inner layer to the outer layer of the plasma membrane, chromatin condensation, DNA fragmentation, and caspase-3 and -9 activation. ISP provoked also cell cycle arrest in the G(2)-M phase. We also showed that the expression of p53 was not modified in ISP-treated cells, but that p21 was induced in a p53-independent manner. Finally, we demonstrated that ISP did not affect the catalytic activity of human topoisomerases I and II. In conclusion, ISP, which promotes cell death by a p53-independent apoptotic pathway, could be an interesting lead for cancer chemotherapy. [less ▲]

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See detailApoptosis induction in human cancer cells by sungucine from Strychnos icaja root
Frederich, Michel ULg; Bentires-Ali, M.; Tits, Monique ULg et al

in Naunyn-Schmiedeberg's Archives of Pharmacology (2003), 367(3), 260-265

Sungucine (SG) and isosungucine (ISG) are bisindole alkaloids characterized by a 5'-23 link between the two parts of the compounds, which are till now specific to Strychnos icaja. In this work, SG and ISG ... [more ▼]

Sungucine (SG) and isosungucine (ISG) are bisindole alkaloids characterized by a 5'-23 link between the two parts of the compounds, which are till now specific to Strychnos icaja. In this work, SG and ISG were submitted to the NCI's in vitro 60 human tumor cell line screen, where SG showed interesting selectivity (6X) against the tested leukemia cell lines. In HL60-treated cells, apoptosis was demonstrated by observation of apoptotic bodies formation, and phosphatidylserine exposition at cell surface. In HeLa-treated cells, the analysis of cellular cycle by flow cytometry showed G1 accumulation and a small sub-G1 peak that could be related to DNA fragmentation characteristic of apoptosis. The eventual role of p53 was analyzed using wild-type HCT-116 colon cancer cells. Nevertheless, p53 and Bax expression were not modified in SG-treated cells. The cleavage of PARP by caspase-3 protease proved that apoptosis was also induced in this line. These results demonstrate that SG induces apoptosis, but also necrosis, in human cancer cell lines. [less ▲]

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See detailIndolomonoterpenic alkaloids from Strychnos icaja roots
Philippe, Geneviève ULg; De Mol, Patrick ULg; Zeches-Hanrot, M. et al

in Phytochemistry (2003), 62(4), 623-629

In the course of our search for new antiplasmodial alkaloids from Strychnos icaja, we have isolated five alkaloids: three monomers, protostrychnine and genostrychnine, previously described in Strychnos ... [more ▼]

In the course of our search for new antiplasmodial alkaloids from Strychnos icaja, we have isolated five alkaloids: three monomers, protostrychnine and genostrychnine, previously described in Strychnos nux-vomica, pseudostrychnine, already found in the leaves of the plant, a new bisindolic alkaloid, named strychnogucine C, and the first naturally occurring trimeric indolomonoterpenic alkaloid: strychnohexamine. This latter trimeric alkaloid presented an antiplasmodial activity against the FCA Plasmodium falciparum line near I muM. (C) 2002 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailIndole alkaloids from Strychnos species and their antiplasmodial and cytotoxic activities
Frederich, Michel ULg; Tits, Monique ULg; Angenot, Luc ULg

in Chemistry of Natural Compounds (2003), 39(6, NOV-DEC), 513-519

Strychnos species (Loganiaceae) have been studied in the laboratory of Pharmacognosy of the University of Liege for more than fifty years. Although investigations into the Strychnos genus have been going ... [more ▼]

Strychnos species (Loganiaceae) have been studied in the laboratory of Pharmacognosy of the University of Liege for more than fifty years. Although investigations into the Strychnos genus have been going on for a long time in the case of Asian tetanizing and American curarizing species, the first chemical and pharmacological screening on African species was undertaken in the early nineteen fifties by the late Prof A. Denoel (University of Liege, Belgium), who examined twenty-five species of Strychnos collected in the Belgian Congo [1]. This research programme was also an offshoot of an inventory of medicinal and toxic plants in Rwanda, carried out during the years 1969-1970. The Belgian scientists were lucky to observe the tribe of Banyambo, living along the Akagera river on the border between Rwanda and Tanzania, where hunters prepared in front of them an arrow poison with Strychnos usambarensis roots and leaves as the main ingredients [2]. Strychnos species have several ethnobotanical uses. A few species are well known for their incorporation into arrow and ordeal poisons, but play more a role in ethnomedicine against fever, rheumatism, worms, ulcers, leprosy, snake-bites, and so forth [3]. In fact, among about one hundred and ninety species, only six would contain strychnine (1) (Strychnos nux-vomica L. [4-7], S. ignatii P. Bergius [8, 9], and S. wallichiana Steud ex DC. [7, 10] from Asia, S. lucida R. Br. [7, 11] from Australia, S. icaja Baillon [1, 12] from Africa, and S. panamensis [13-15] from South America). Strychnos alkaloids are in fact an example of molecular and pharmacological biodiversity. More than 300 different Strychnos alkaloids have been isolated to date and theypresent various biological activities in several fields: parasitology (amoebiasis, paludism, etc.) [ 16-18], cancer [ 19-22], neurology (tetanizing or curarizing effects) [14, 23, 24-26], inflammation [27], and so on. [less ▲]

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See detailEffects of prodelphinidins isolated from Ribes nigrum leaves on chondrocyte metabolism and COX activity
Angenot, Luc ULg; Garbacki, Nancy ULg; Damas, Jacques et al

Poster (2002, October 29)

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See detailLes substances naturelles dans la lutte contre le paludisme
Frederich, Michel ULg

Scientific conference (2002, October 17)

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See detailAntiplasmodial activity of alkaloids from various Strychnos species
Frederich, Michel ULg; Jacquier, M. J.; Thepenier, P. et al

in Journal of Natural Products (2002), 65(10), 1381-1386

The in vitro antiplasmodial activities of 69 alkaloids from various Strychnos species were evaluated against chloroquine-resistant and chloroquine-sensitive lines of Plasmodium falciparum. The compounds ... [more ▼]

The in vitro antiplasmodial activities of 69 alkaloids from various Strychnos species were evaluated against chloroquine-resistant and chloroquine-sensitive lines of Plasmodium falciparum. The compounds, comprising mainly indolomonoterpenoid alkaloids, exhibited a wide range of biological potencies in the antiplasmodial assays. The most active alkaloids were also tested for cytotoxicity against HCT-116 colon cancer cells to determine their antiplasmodial selectivity. As a result of these studies, structure-activity relationships for these alkaloids have begun to emerge. Alkaloids presenting four types of bisindole skeleton exhibited potent and selective activities against Plasmodium. They were sungucine-type (IC(50) values ranging from 80 nM to 10 microM), longicaudatine-type (IC(50) values ranging from 0.5 to 10 microM), matopensine-type (IC(50) values ranging from 150 nM to 10 microM), and usambarine-type alkaloids. Within the last structural type, isostrychnopentamine (49) and ochrolifuanine A (46) were found to be active against chloroquine-sensitive and -resistant strains (IC(50) values of 100-150 and 100-500 nM, respectively), and dihydrousambarensine (51) exhibited a 30-fold higher activity against the chloroquine-resistant strain (IC(50) = 32 nM) than against the chloroquine-sensitive one. [less ▲]

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See detailActivités cytotoxiques et apoptotiques de gigantéosides D et E isolés de Cephalaria gigantea
Gerkens, Pascal; Frederich, Michel ULg; Mshvildadze, Vakhtang et al

Poster (2002, September)

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See detailNew trends in anti-malarial agents
Frederich, Michel ULg; Dogné, Jean-Michel ULg; Angenot, Luc ULg et al

in Current Medicinal Chemistry (2002), 9(15), 1435-1456

Malaria is the major parasitic infection in many tropical and subtropical regions, leading to more than one million deaths (principally young African children) out of 400 million cases each year (WHO ... [more ▼]

Malaria is the major parasitic infection in many tropical and subtropical regions, leading to more than one million deaths (principally young African children) out of 400 million cases each year (WHO world health report 2000). More than half of the world's population live in areas where they remain at risk of malaria infection. During last years, the situation has worsened in many ways, mainly due to malarial parasites becoming increasingly resistant to several antimalarial drugs. Furthermore, the control of malaria is becoming more complicated by the parallel spread of resistance of the mosquito vector to currently available insecticides. Discovering new drugs in this field is therefore a health priority. Several new molecules are under investigation. This review describes the classical treatments of malaria and the latest discoveries in antimalarial agents, especially artemisinin and its recent derivatives as well as the novel peroxidic compounds. [less ▲]

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See detailApoptosis of HL-60 leukemia cells induced by the bisindole alkaloids sungucine and isosungucine from Strychnos icaja
Lansiaux, A.; Bailly, Christian; Houssier, Claude ULg et al

in Planta Medica (2002), 68(7), 591-595

Sungucine and isosungucine are two bisindole alkaloids isolated from the roots of the African plant Strychnos icaja Baillon. They both exhibit antiplasmodial activities but also show cytotoxic effects ... [more ▼]

Sungucine and isosungucine are two bisindole alkaloids isolated from the roots of the African plant Strychnos icaja Baillon. They both exhibit antiplasmodial activities but also show cytotoxic effects against human cancer cell lines. In order to elucidate their mechanism of action, we have investigated the interaction of the alkaloids with DNA and their capacity to inhibit nucleic acids and protein synthesis in the human HL-60 promyelocytic leukemia cell line. Cell treatment with both sungucine and isosungucine leads to the appearance of a hypo-diploid DNA content peak. Western blotting analysis reveals that the two alkaloids induce cleavage of the poly(ADP-ribose) polymerase (PARP) and promote the cleavage of a caspase-3 DEVD peptide substrate. The activation of the caspase cascade is accompanied with a fragmentation of DNA in cells, as revealed by the TUNEL assay. Altogether, the results shed light on the mechanism of action of these two plant alkaloids and identify signaling factors involved in (iso)sungucine-induced apoptosis in HL-60 cells. [less ▲]

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See detailIn vitro antiplasmodial activity of Tithonia diversifolia and identification of its main active constituent: tagitinin C.
Goffin, Eric ULg; Ziemons, Eric ULg; De Mol, Patrick ULg et al

in Planta Medica (2002), 68(6), 543-5

The antimalarial properties of Tithonia diversifolia, an Asteraceae traditionally used to treat malaria, were investigated in vitro against three strains of Plasmodium falciparum. The ether extract from ... [more ▼]

The antimalarial properties of Tithonia diversifolia, an Asteraceae traditionally used to treat malaria, were investigated in vitro against three strains of Plasmodium falciparum. The ether extract from aerial parts of the plant collected in Sao Tome e Principe, demonstrated good antiplasmodial activity (IC 50 on FCA strain: 0.75 microg/ml). A bioassay guided fractionation of this extract led to the isolation of the known sesquiterpene lactone tagitinin C as an active component against Plasmodium (IC 50 on FCA strain: 0.33 microg/ml), but also possessing cytotoxic properties (IC 50 on HTC-116 cells: 0.706 microg/ml). [less ▲]

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