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R Anton

Publications and source records attributed to R Anton.

At least 19 recordsLinked to original sources
PubMed2006

In vitro antiprotozoal activities and cytotoxicity of some selected Cameroonian medicinal plants.

Eight extracts from seven selected Cameroonian medicinal plants, traditionally used to treat malaria and other protozoal diseases, were tested in vitro for their antiprotozoal activities against Plasmodium falciparum K1 chloroquine-resistant strain, Leishmania donovani, Trypanosoma cruzi and Trypanosoma brucei rhodesiense, protozoa responsible for malaria, visceral leishmaniasis, Chagas disease and African trypanosomiasis, respectively. The most active extract against Plasmodium falciparum K1 strain and Trypanosoma brucei rhodesiense was the methanolic extract of Albizia zygia (Fabaceae) stem bark with IC(50) values of 1.0 microg/ml and 0.2 microg/ml, respectively. Five extracts showed IC(50) values below 5mug/ml against Leishmania donovani, with the methanolic seed extract of Harungana madagascarensis showing the highest activity, but only the methanolic extract of Albizia zygia showed activity against Trypanosoma cruzi. Cytotoxicity and selectivity indexes were estimated for the most active extracts. The best ratio of cytotoxicity to antiplasmodial activity (SI(a)=14) was established for the methanolic leaf extract of Symphonia globulifera (Clusiaceae), while the methanolic stem bark extract of Albizia zygia showed the best ratio of cytotoxicity to antitrypanosomal activity (SI(b)=22.5).

Albizzia↗
PubMed2005

Comparative antiplasmodial, leishmanicidal and antitrypanosomal activities of several biflavonoids.

The antiplasmodial, leishmanicidal and antitrypanosomal activities of eight natural biflavonoids were estimated in vitro on a chloroquine-resistant strain of Plasmodium falciparum, axenically grown Leishmania donovani amastigotes and Trypanosoma cruzi trypomastigotes and Trypanosoma brucei rhodesiense bloodstream forms. Lanaroflavone showed the highest antiplasmodial activity (IC(50) = 0.48 microM), isoginkgetin was the most active leishmanicidal compound (IC(50) = 1.9 microM), whereas ginkgetin (IC(50) = 11 microM) and isoginkgetin (IC(50) = 13 microM) showed the best antitrypanosomal activity in our assays. The cytotoxicity and the selectivity indices for the most active compounds were also estimated. Lanaroflavone exhibited a high selectivity index value (SI = 159), indicating selective antiplasmodial activity.

Animals↗
PubMed2004

A bioactive biflavonoid from Campnosperma panamense.

Lanaroflavone (1), a biflavonoid isolated from the methanol extract of the aerial part of Campnosperma panamense by bioguided fractionation, has been assessed for in vitro antiprotozoal activity. Lanaroflavone showed both antimalarial and leishmanicidal activities, but was inactive against Chagas disease vector, Trypanosoma cruzi.

Anacardiaceae↗
PubMed2003

Guidance for the safety assessment of botanicals and botanical preparations for use in food and food supplements.

There is a growing interest by both consumers and industry for the development of food products with 'functional' properties, or health benefits. These products may take the form of dietary supplements or of foods. The health benefits are given by particular ingredients, and in many cases these are derived from botanicals. The variety of plants providing these functions is large, ranging from staple food sources such as cereals, fruits and vegetables, to herbals as used in traditional medicine. The food or ingredient conferring health properties may consist of the plants themselves, extracts thereof, or more purified components. The scientific literature is abundant with articles not only on the beneficial properties, but also on possible adverse health effects of plants and their components. The present report discusses the data required to determine the safe use of these types of ingredients, and provides advice on the development of risk assessment strategies consistent with due diligence under existing food regulations. Product specifications, composition and characterisation of standardised and authentic materials, documented history of use and comparison to existing products (taking into account the effect of industrial processing), description of the intended use and consequent exposure are highlighted as key background information on which to base a risk evaluation. The extent of experimental investigation required, such as in vitro, animal, and/or human studies, depends on the adequacy of this information. A decision tree is presented as an aid to determine the extent of data requirements based on product comparison. The ultimate safety in use depends on the establishment of an adequate safety margin between expected exposure and identified potential hazards. Health hazards may arise from inherent toxicities or contaminants of the plant materials, including the mechanism of the intended beneficial effect. A lower safety margin may therefore be expected than for food ingredients or additives where no physiological effects are intended. In rare cases, post launch monitoring programmes may be envisaged to confirm expected exposures and adequacy of the safety margin. This guidance document was elaborated by an expert group of the Natural Toxin Task Force of the European Branch of the International Life Sciences Institute--ILSI Europe and discussed with a wider audience of scientists at a workshop held on 13-15 May 2002 in Marseille, France.

Animals↗
PubMed2001

Thickness inhomogeneity and fluorescence effects in EXAFS spectroscopy for powder samples: solution of the inverse problem.

For thin powder samples EXAFS spectra are often suffered from thickness inhomogeneity and for thick samples from fluorescence at energies above edge absorption. As a result EXAFS amplitude is decreased and information about the coordination numbers is distorted. For correction of x-ray absorption spectra on inhomogeneity and fluorescence effects we propose a new method of solving an inverse problem. Model calculations are carried out. This method is applied to preliminary processing EXAFS spectra for Ni-Mn alloys.

Journal Article↗
PubMed2001

Saponins from Strasburgeria robusta.

The isolation of three saponins, 24-hydroxytormentic acid ester glucoside (1), niga-ichigoside F1 (2) and niga-ichigoside F2 (3), from the stem bark of Strasburgeria robusta, an endemic plant from New Caledonia, is reported.

Humans↗
PubMed2001

Antiprotozoal activities of Colombian plants.

In our search for therapeutical alternatives for antiprotozoal chemotherapy, we collected a selection of 44 plants from western Colombia upon ethnopharmacological and chemotaxonomic considerations. Polar and apolar extracts of these species were examined for antimalarial activity using in vitro tests with two clones of Plasmodium falciparum. Leishmanicidal and trypanocidal activity were determined in vitro using promastigote and amastigote forms of several strains of Leishmania sp. and epimastigotes of Trypanosoma cruzi. Among the selected plants, the 15 following species showed good or very good antiprotozoal activity in vitro: Aspidosperma megalocarpon, Campnosperma panamense, Conobea scoparioides, Guarea polymera, Guarea guidonia, Guatteria amplifolia, Huberodendron patinoi, Hygrophila guianensis, Jacaranda caucana, Marila laxiflora, Otoba novogranatensis, Otoba parviflora, Protium amplium, Swinglea glutinosa and Tabernaemontana obliqua. Cytotoxicity was assessed in U-937 cells and the ratio of cytotoxicity to antiprotozoal activity was determined for the active extracts. Ten extracts from eight species showed selectivity indexes > or = 10. Among the extracts that showed leishmanicidal activity, the methylene chloride extract of leaves from C. scoparioides showed a selectivity index in the same range that the one of the Glucantime control. Several of the active leishmanicidal plants are traditionally used against leishmaniasis by the population of the concerned area.

Animals↗
PubMed2001

Bioactive acridone alkaloids from Swinglea glutinosa.

A new prenylated acridone alkaloid, 1,3,5-trihydroxy-2,8-bis(3-methylbut-2-enyl)-10-methyl-9-acridone (1), was isolated from the stembark of Swinglea glutinosa, along with three known acridone alkaloids, 5-hydroxynoracronycine (2), 1,3,5-trihydroxy-4-methoxy-2-(3-methylbut-2-enyl)-10-methyl-9-acridone (3), and 1,3,5-trihydroxy-4-methoxy-10-methylacridone (4). The isolated alkaloids were assessed in vitro against chloroquine-sensitive and -resistant Plasmodium falciparum strains and for cytotoxicity using HeLa cells.

Acridines↗
PubMed2001

Triterpenoid saponins from Isertia pittieri.

Two new 27-nor-triterpenoid saponins, pyrocincholic acid 3 beta-O-beta-D-quinovopyranosyl-28-[beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl] ester (1) and pyrocincholic acid 3 beta-O-beta-D-quinovopyranosyl(1-->6)-beta-D-glucopyranosyl-28-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl] ester (2) were isolated from the stem bark of Isertia pittieri, together with two known bidesmosidic quinovic acid glycosides. The structures of 1 and 2 were determined on the basis of spectroscopic studies.

Chromatography, High Pressure Liquid↗
PubMed2001

Clinical review of inhalants.

While the rate of inhalant abuse continues to rise in this country, it remains one of the least studied or discussed groups of abused substances. This review focuses on the current knowledge of the epidemiology, pharmacology, and sequela of inhalant abuse. We will discuss three groups of inhalants: volatile solvents, nitrous oxide, and nitrites. We will then conclude by proposing means by which inhalant abuse may be prevented and treated.

Administration, Inhalation↗
PubMed2001

Carbohydrate deficient transferrin in abstaining patients with end-stage liver disease.

BACKGROUND: Carbohydrate deficient transferrin (CDT), a biochemical marker of chronic alcohol consumption, is used by researchers and clinicians alike in a variety of populations. Levels of CDT may be affected by certain types of medical illnesses and conditions. Thus the interpretation of CDT results may need to be carefully examined in these populations. Because CDT is synthesized, glycosylated, and secreted by the liver, the use of CDT values in patients with liver disease has been an area of focused interest. METHODS: We evaluated the CDT values of 79 abstaining patients with end-stage liver disease. These patients were recruited from a liver transplant clinic while they were listed and waiting for transplantation. Patients were determined to be abstaining both by interview and by random blood alcohol levels in those with a diagnosis of alcoholic liver disease. The severity of the liver disease was categorized by the Child-Pugh score. Correlations were determined between CDT values and liver enzymes, and Child-Pugh scores and liver diagnosis. RESULTS: Nearly 50% of the patients had a CDT value of 2.6% or above, indicating a clinically positive value. There were strong correlations between CDT and a number of biochemical and physical variables, most importantly the Child-Pugh score (r = 0.52, p = 0.000). Specific liver diseases were not associated with absolute CDT values. However, patients with hepatitis C (HCV) had a significantly higher chance of having a clinically positive CDT compared with patients with other types of liver diseases. CONCLUSIONS: These results suggest that an elevated CDT value may not accurately represent alcohol consumption in patients with advanced liver disease. In fact, in such patients, the CDT may become a marker for the degree of liver impairment in alcoholic and nonalcoholic liver disease. CDT values should be viewed with caution in any patient with liver disease especially when the degree of cirrhosis reaches a Child-Pugh score of C (total score of 10 or above).

Alcohol Drinking↗
PubMed2001

Adolescent Obsessive-Compulsive Drinking Scale: an assessment tool for problem drinking.

Alcoholism has been studied in adults and found to share obsessive-compulsive characteristics. The Yale-Brown Obsessive Compulsive Scale (YBOC) was used to quantify the measurements of this disorder. This study adapted the YBOC for use with adolescents/young adults in an attempt to measure the "craving" expressed as obsessive and compulsive phenomenon. The primary findings show that the obsessive compulsive dimensions of alcohol cravings, as described in adult populations, also exist in adolescent/young adults. The Adolescent Obsessive Compulsive Drinking Scale (A-OCDS) was developed utilizing idioms and language typical for the 17-20 age group. Various quantitative evaluations proved that the Interference and Irresistibility sub-scales were the primary dimensions causing the obsessive behavior. This study begins to address this aspect of adolescent substance abuse utilizing a tool that is easy to administer. Because of the ease of use, although not a diagnostic instrument, the A-OCDS may be useful for identifying problem drinking in adolescents as well as detecting impairment in function related to drinking.

Adolescent↗
PubMed2000

Modulation of mistletoe (Viscum album L.) lectins cytotoxicity by carbohydrates and serum glycoproteins.

Three D-galactose and/or N-acetyl-D-galactosamine specific mistletoe lectins, ML I, ML II and ML III, were purified by affinity chromatography followed by cation exchange chromatography. These lectins were toxic for Molt 4 cells in culture at concentrations in the pg/ml range, ML III being the most cytotoxic. Carbohydrates able to bind to the B-chain of these lectins inhibited their toxic activity. The digalactosides Gal beta 1,2Gal beta-allyl and Gal beta 1,3Gal beta-allyl were 60 and 30 times, respectively, more potent than D-galactose in their ability to protect the cells from the ML I cytotoxicity. N-acetyl-D-galactosamine and rho-nitrophenyl N-acetylgalactosamine protected mainly from the toxic effects of ML II and III. Protection from cytotoxicity varied in the same order as the affinity of the tested carbohydrates for lectins. Serum glycoproteins particularly haptoglobin, but also alpha 1-acid glycoprotein and transferrin, notably inhibited the cytotoxicity of the lectins. This effect was due to the binding of lectin to the sugar moiety of the glycoprotein because deglycosylated haptoglobin did not have a protective activity on Molt 4 cells. Inhibition of the cytotoxicity of lectins by serum glycoproteins explains why mistletoe extracts containing lectins can be administered to cancer patients without harmful effects.

Antineoplastic Agents↗
PubMed2000

Suppression of azoxymethane-induced preneoplastic lesions and inhibition of cyclooxygenase-2 activity in the colonic mucosa of rats drinking a crude green tea extract.

We determined the effects of a crude green tea extract given as drinking fluid on the promotion/progression phase of colon carcinogenesis in rats after induction of the neoplastic process by azoxymethane. Adult Wistar rats were given azoxymethane (15 mg/kg i.p.) once a week for two weeks. One week after the second injection, the rats were randomly divided into two groups. One group (n = 8) received daily prepared aqueous solutions of green tea extracts (GTE; 0.02%, wt/vol); the control group (n = 8) received tap water. After six weeks, rats receiving GTE showed a 60% reduction in the number of colonic preneoplastic lesions (aberrant crypts). The number of individual crypts per aberrant crypt focus (crypt multiplicity) was significantly reduced in the GTE group; the majority (80%) of the remaining aberrant foci contained only one or two preneoplastic crypts. A significant and selective decrease of cyclooxygenase (COX)-2 activity was observed in the colon of rats receiving GTE (23 +/- 3 vs. 117 +/- 30 mU/mg protein in controls), whereas COX-1 showed no alterations. Our data demonstrate that GTE reduces COX-2 and suppresses the formation of colonic preneoplastic lesions. They provide new insights into the mechanism of chemopreventive and anti-inflammatory properties of green tea.

Animals↗
PubMed2000

Talk is cheap: measuring drinking outcomes in clinical trials.

OBJECTIVE: To evaluate the correspondence among measures of self-reported drinking, standard biological indicators and the reports of collateral informants, and to identify patient characteristics associated with observed discrepancies among these three sources of research data. METHOD: Using data collected from a large-scale clinical trial of treatment matching with alcoholics (N = 1,726), these three alternative outcome measures were compared at the time of admission to treatment and at 12 months after the end of treatment. RESULTS: Patient self-reports and collateral reports agreed most (97.1%) at treatment admission when heavy drinking was unlikely to be denied. In contrast, liver function tests were relatively insensitive, with positive serum gamma-glutamyl transpeptidase (GGTP) values obtained from only 39.7% of those who admitted to heavy drinking. At 15-month follow-up the correspondence between client self-report and collateral report decreased to 84.7%, but agreement with blood chemistry values increased to 51.6%. When discrepancies occurred, they still indicated that the client' s self-report is more sensitive to the amount of drinking than the biochemical measures. Patients who presented discrepant results tended to have more severe drinking problems, more previous treatments, higher levels of pretreatment drinking and significantly greater levels of cognitive impairment, all of which could potentially interfere with accurate recall. CONCLUSIONS: In clinical trials using self-selected research volunteers, biochemical tests and collateral informant reports do not add sufficiently to self-report measurement accuracy to warrant their routine use. Resources devoted to collecting these alternative sources of outcome data might be better invested in interview procedures designed to increase the validity of self-report information.

Adult↗