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Biomedical subjects

E Ollivier

Publications and source records attributed to E Ollivier.

At least 19 recordsLinked to original sources
PubMed2006

Effect of green tea extracts on liver functions in Wistar rats.

An herbal medicinal product (Exolise) containing as active ingredient an hydro-alcoholic extract of green tea named AR25 (standardized to 25% catechins) has been implicated in hepatic failures, leading to the withdrawal of the marketing authorization. The active ingredient of Exolise being manufactured with 80% ethanol, the question to know whether the extraction solvent could introduce some toxic components was hypothesized. Two investigations were conducted in Wistar rats to determine if repeated oral administration of different green tea extracts could corroborate the reported hepatotoxicity in humans. In a preliminary 6 week-study, experimental groups (n=9/group) received either the vehicle or a methylene chloride extract (2500 mg/kg body weight) where potential non-polar hepatotoxin(s) could be concentrated. In a second experiment (12 week-study), rats were divided in three groups (n=10/group) and treated with either the vehicle, or an aqueous extract (1400 mg/kg) or AR25 green tea extract (2000 mg/kg). Rat liver functions were assessed by serum biochemistry of hepatotoxicity markers. No sign of evidence of characteristic hepatotoxicity was found in rats treated with very high amount of different green tea extracts in these two experiments (respectively a daily dosage, which was about 900 and 80 times higher to the therapeutic daily dosage of Exolise.

Animals↗
PubMed2005

Screening of 14 alkaloids isolated from Haplophyllum A. Juss. for their cytotoxic properties.

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.

Alkaloids↗
PubMed2005

In vitro cytotoxic, antileishmanial and antifungal activities of ethnopharmacologically selected Gabonese plants.

Seventy-seven crude extracts from leaves and stem barks of 15 Gabonese plants used in traditional medicine were evaluated for their cytotoxic, antileishmanial and antifungal activities. Most of the extracts exhibited cytotoxic activities toward human monocytes, and most particularly the hydromethanolic 50% (v/v) fraction of Ganophyllum giganteum leaves (IC(50)=1.3 microg/ml) as well as the methanolic extracts of Polyalthia suaveolens, Dioscorea preussii, Augouardia letestui leaves and Cola lizae stem barks (IC(50)<5 microg/ml). The methanolic extract of Polyalthia suaveolens displayed a strong antiproliferative activity against the promastigote form of Leishmania infantum parasites and presented a good antifungal activity on all the tested strains (IC(50)<1mg/ml). This extract was divided into six fractions: fraction F6 demonstrated a cytotoxic activity stronger than those of the crude extract (IC(50)=0.6 microg/ml), fractions F4 and F5 were devoid of cytotoxicity (IC(50)>100 microg/ml) and displayed interesting antileishmanial activity against the intracellular amastigote form of the parasite (IC(50)=5.6 and 12.4 microg/ml), respectively. However, the antifungal activity observed for the crude extract could not be recovered in the corresponding fractions.

Animals↗
PubMed2003

Antiplasmodial activity of alkaloid extracts from Pavetta crassipes (K. Schum) and Acanthospermum hispidum (DC), two plants used in traditional medicine in Burkina Faso.

In the course of the search for new antimalarial compounds, a study of plants traditionally used against malaria in Burkina Faso was made. An ethnobotanical study permitted the identification of plants currently used by the traditional healers and herbalists. Two plants among them were selected for further study: Pavetta crassipes (K. Schum) and Acanthospermum hispidum (DC). Alkaloid extracts of these plants were tested in vitro against two reference clones of Plasmodium falciparum: the W2 chloroquine-resistant and the D6 chloroquine-sensitive strains. Significant inhibitory activity was observed with Pavetta crassipes (IC(50)=1.23 microg/ml) and A. hispidum (IC(50)=5.02 microg/ml). Antiplasmodial activity was also evaluated against six Plasmodium falciparum isolates from children between 4 and 10 years old. The IC(50) values for the alkaloid extracts were in the range 25-670 ng/ml. These results indicated that P. falciparum wild strains were more sensitive to the alkaloid extracts than strains maintained in continuous culture. Moreover, the alkaloid extracts exhibit good in vitro antimalarial activity and weak cytotoxicity against three human cell lines (THP1, normal melanocytes, HTB-66). Isolation and structural determination are now necessary in order to precisely determine the active compounds.

Alkaloids↗
PubMed2003

Ethnobotanical survey and in vitro antiplasmodial activity of plants used in traditional medicine in Burkina Faso.

In Burkina Faso, most people in particular, in rural areas, use traditional medicine and medicinal plants to treat usual diseases. In the course of new antimalarial compounds, an ethnobotanical survey has been conducted in different regions. Seven plants, often cited by traditional practitioners and not chemically investigated, have been selected for an antiplasmodial screening: Pavetta crassipes (K. Schum), Acanthospermum hispidum (DC), Terminalia macroptera (Guill. et Perr), Cassia siamea (Lam), Ficus sycomorus (L), Fadogia agrestis (Schweinf. Ex Hiern) and Crossopteryx febrifuga (AFZ. Ex G. Don) Benth. Basic, chloroform, methanol, water-methanol and aqueous crude extracts have been prepared and tested on Plasmodium falciparum chloroquine-resistant W2 strain. A significant activity has been observed with alkaloid extract of P. crassipes (IC(50)<4 microg/ml), of A. hispidum, C. febrifuga, and F. agrestis (4<IC(50)<10 microg/ml). The best result is obtained with aqueous extract of T. macroptera with an IC(50)=1 microg/ml. These results confirm the traditional use of these plants.

Animals↗
PubMed2002

Antimalarial activity of extracts and alkaloids isolated from six plants used in traditional medicine in Mali and Sao Tome.

Methanol and chloroform extracts were prepared from various parts of four plants collected in Mali: Guiera senegalensis (Gmel.) Combretaceae, Feretia apodanthera (Del.) Rubiaceae, Combretum micranthum (Don.) Combretaceae, Securidaca longepedunculata (Fres.) Polygalaceae and two plants -collected in Sao Tome: Pycnanthus angolensis (Welw.) Myristicaceae and Morinda citrifolia (Benth.) Rubiaceae were assessed for their in vitro antimalarial activity and their cytotoxic effects on human monocytes (THP1 cells) by flow cytometry. The methanol extract of leaves of Feretia apodanthera and the chloroform extract of roots of Guiera senegalensis exhibited a pronounced antimalarial activity. Two alkaloids isolated from the active extract of Guiera senegalensis, harman and tetrahydroharman, showed antimalarial activity (IC(50) lower than 4 microg/mL) and displayed low toxicity against THP1. Moreover, the decrease of THP1 cells in S phase of the cell cycle, after treatment with harman and tetrahydroharman, was probably due to an inhibition of total protein synthesis.

Alkaloids↗
PubMed2002

Deciphering Arabidopsis thaliana gene neighborhoods through bibliographic co-citations.

In the framework of genome annotation, scientific literature is obviously the major source of biological knowledge. The aim of the work described in this paper is to exploit this source of data for the model plant Arabidopsis thaliana. The first step has consisted in constituting a relevant bibliographic references dataset for plant genomic research. Genes co-citations have then been systematically annotated in this reference dataset, starting from the simple idea that if genes are cited in the same publication, they must probably share some related functional properties. In order to deal with the synonymous gene name problem, a gene name reference list has been constituted starting from A. thaliana SwissProt entries. This list was used to build clusters of co-cited genes by a single linkage procedure such that any gene in a given cluster possesses at least one co-cited partner in the same cluster. Analysis of the clusters demonstrate the biological consistency of this approach, with only very few fortuitous links. As an example, a cluster including genes related to flowering time is more deeply described in the paper. Finally, a graphical representation of each cluster was performed, which provides a convenient way to retrieve the genes (the nodes of the graphs) and the references in which they were co-cited (the edges of the graphs). All the results can be accessed at the URL http://chlora.Igi.infobiogen.fr:1234/bib_arath/.

Arabidopsis↗
PubMed2001

Massive sequence comparisons as a help in annotating genomic sequences.

An all-by-all comparison of all the publicly available protein sequences from plants has been performed, followed by a clusterization process. Within each of the 1064 resulting clusters-containing sequences that are orthologous as well as paralogous-the sequences have been submitted to a pyramidal classification and their domains delineated by an automated procedure à la. This process provides a means for easily checking for any apparent inconsistency in a cluster, for example, whether one sequence is shorter or longer than the others, one domain is missing, etc. In such cases, the alignment of the DNA sequence of the gene with that of a close homologous protein often reveals (in 10% of the clusters) probable sequencing errors (leading to frameshifts) or probable wrong intron/exon predictions. The composition of the clusters, their pyramidal classifications, and domain decomposition, as well as our comments when appropriate, are available from http://chlora.infobiogen.fr:1234/PHYTOPROT.

Amino Acid Sequence↗
PubMed2000

Antimalarial activity of four plants used in traditional medicine in Mali.

Mitragyna inermis (De Willd.) O. Kuntze Rubiaceae, Nauclea latifolia (Sm.) Rubiaceae, Glinus oppositofolius (Linn) Molluginaceae and Trichilia roka (Forsk.) Chiv. Meliaceae were investigated for their in vitro antimalarial activity. Leaves, roots and stem barks were submitted to aqueous, hydromethano and chloroform extractions and antimalarial activity was evaluated by microscopic and flow cytometric analysis. The results present evidence that the alkaloids contained in chloroform extracts and ursolic acid, purified from the hydromethanol extract of M. inermis induced a significant decrease of parasite proliferation. However, aqueous extracts, traditionally used for medication did not show high antimalarial activity. Statistical comparison between microscopic and cytometric analysis demonstrated the validity of this new technique for the screening of active antimalarial compounds isolated from plants.

Animals↗
PubMed2000

Structure and antiprotozoal activity of triterpenoid saponins from Glinus oppositifolius.

Two new triterpenoid saponins, glinosides A and B, isolated from the aerial parts of Glinus oppositifolius, have been characterized by 1D, 2D, NMR and high-resolution mass spectral (HRMS) techniques. Their structures were established respectively as 16-O-(beta-arabinopyranosyl)-3-oxo-12,16 beta,21 beta,22-tetrahydroxyhopane for glinoside A and 16-O-(beta-arabinopyranosyl)-3-oxo-12,16 beta,22-trihydroxyhopane for glinoside B. Results presented evidence that fractions had a better antiplasmodial activity (IC50 = 31.80 micrograms/ml) than pure glinoside A (IC50 = 42.30 micrograms/ml).

Animals↗
PubMed1999

Codon usage as a tool to predict the cellular location of eukaryotic ribosomal proteins and aminoacyl-tRNA synthetases.

In spite of many efforts, the prediction of the location of proteins in eukaryotic cells (cytoplasm, mitochondrion or chloroplast) is still far from straightforward. In some cases (e.g. ribosomal proteins and aminoacyl-tRNA synthetases) both the cytoplasmic proteins and their organellar counterparts are encoded by the nuclear genome. A factorial correspondence analysis of the codon usage in yeast and Caenorhabditis elegans shows that the codon usage of those nuclear genes encoding ribosomal proteins or aminoacyl-tRNA synthetases is markedly different, depending on the final location of the proteins (cytoplasmic or mitochondrial). As a consequence, the location of such proteins-whose sequences are now frequently determined by systematic genomic sequencing-can be easily and quickly predicted. A WWW interface has been developed, aimed at providing a user-friendly tool for codon usage pattern analysis. It is available from http://www.genetique.uvsq.fr/afc.html

Amino Acyl-tRNA Synthetases↗
PubMed1999

Two new pyridine monoterpene alkaloids by chemical conversion of a commercial extract of harpagophytum procumbens

The treatment of harpagide (1), harpagoside (2), or 8-O-p-coumaroylharpagide (3), the main iridoids of Harpagophytum procumbens and Harpagophytum zeyheri, with NH3 and HCl led to aucubinine B(4), a pyridine monoterpene alkaloid (PMTA). A similar procedure applied to a commercial extract of H. procumbens yielded 4 and two new PMTAs named beatrine A (5) and beatrine B (6). The structures of these new PMTAs were established using ESIMS and 2D NMR. Their semisynthesis was analyzed in terms of reaction mechanisms.

Journal Article↗
PubMed1999

Formation of nitrogen-containing metabolites from the main iridoids of Harpagophytum procumbens and H. zeyheri by human intestinal bacteria.

The study of the metabolism of iridoid glycosides from Harpagophytum procumbens and Harpagophytum zeyheri by human intestinal bacteria, was realized in order to elucidate compounds responsible for the pharmacological activities of Harpagophytum. Harpagide, harpagoside and 8-O-p-coumaroyl-harpagide were transformed into the pyridine monoterpene alkaloid aucubinine B by human fecal flora and by bacteria isolated from this flora. Aucubinine B was also prepared from harpagide, harpagoside and 8-O-p-coumaroylharpagide, by beta-glucosidase in the presence of NH4+.

Alkaloids↗
PubMed1998

A sulfated saponin from bupleurum rigidum

A new sulfated triterpene glycoside with the sulfate group located in an unusual position in the carbohydrate moiety, was isolated from the MeOH extract of the aerial parts of Bupleurum rigidum. This compound was identified by a combination of chemical degradation and spectral methods as 3beta,16beta,23-trihydroxy-13, 28-epoxyolean-11-en-3beta-yl-beta-D-glucopyranosyl-(1-->2)[4-sulfate- beta-D-glucopyranosyl-(1-->3)]-beta-D-fucopyranoside (sandrosaponin I) (1). In addition, the known compound 3beta,16beta, 23-trihydroxy-13, 28-epoxyolean-11-en-3beta-yl-beta-D-glucopyranosyl-(1-->2)[beta-D-glu copyranosyl-(1-->3)]beta-D-fucopyranoside (2) was isolated in the present investigation.

Journal Article↗
PubMed1997

An analytical study, anti-inflammatory and analgesic effects of Harpagophytum procumbens and Harpagophytum zeyheri.

The iridoids of Harpagophytum procumbens and Harpagophytum zeyheri were studied by CLHP. Harpagoside is the main iridoid for both drugs whereas 8-p-coumaroylharpagide is a representative iridoid of Harpagophytum zeyheri only. The ratio harpagoside/8-p-coumaroylharpagide can be used to distinguish chemically both species. For commercial dried aqueous extracts this ratio is intermediate because they are probably prepared from a mixture of H. procumbens and H. zeyheri drugs. The aqueous extracts of both drugs show similar analgesic and anti-inflammatory properties. Harpagophytum procumbens and Harpagophytum zeyheri should be accepted as sources for the drug Harpagophyti radix.

Analgesics↗
PubMed1997

Detection of significant patterns by compression algorithms: the case of approximate tandem repeats in DNA sequences.

MOTIVATION: Compression algorithms can be used to analyse genetic sequences. A compression algorithm tests a given property on the sequence and uses it to encode the sequence: if the property is true, it reveals some structure of the sequence which can be described briefly, this yields a description of the sequence which is shorter than the sequence of nucleotides given in extenso. The more a sequence is compressed by the algorithm, the more significant is the property for that sequence. RESULTS: We present a compression algorithm that tests the presence of a particular type of dosDNA (defined ordered sequence-DNA): approximate tandem repeats of small motifs (i.e. of lengths < 4). This algorithm has been experimented with on four yeast chromosomes. The presence of approximate tandem repeats seems to be a uniform structural property of yeast chromosomes.

Algorithms↗