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Biomedical subjects

A Lobstein

Publications and source records attributed to A Lobstein.

At least 19 recordsLinked to original sources
PubMed2006

Anti-proliferative effect of Euphorbia stenoclada in human airway smooth muscle cells in culture.

The ethanolic extract of a Malagasy species Euphorbia stenoclada (ES) (Euphorbiaceae), traditionally used as a herbal remedy against asthma and acute bronchitis, was tested to evaluate possible anti-proliferative activity on human airway smooth muscle cells (HASMC). The ES ethanolic extract totally abolished the interleukin-1beta (IL-1beta) induced proliferation of HASMC (IC(50)=0.73+/-0.08 microg/mL). No cytotoxic effect was observed up to 20 microg/mL. A bioassay-guided fractionation of the ethanolic extract was performed by reversed-phase (RP) flash chromatography, giving five fractions (FA to FE) where fraction FE was the only active one (IC(50)=0.38+/-0.02 microg/mL). The purification of this bioactive fraction FE was carried out by RP-HPLC affording six sub-fractions 1-6, and only sub-fraction 5 kept the anti-proliferative activity. Its major constituent was identified as quercetin (IC(50)=0.49+/-0.12 microg/mL) by means of HPLC/UV/MS and co-elution with the authentic standard. Quercitrin was also identified in the fraction FE but was inactive. A structure-activity relationship with flavonols determined that methylation reduced the anti-proliferative activity whereas glycosylation abolished it. The present study shows that the anti-proliferative properties of Euphorbia stenoclada are mediated through the presence of quercetin that may explain the traditional use of this plant as a remedy against asthma.

Anti-Asthmatic Agents↗
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↗
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↗
PubMed1998

Natural dietary polyphenolic compounds cause endothelium-dependent vasorelaxation in rat thoracic aorta.

This study investigated the possible active principles which support the endothelial nitric oxide-dependent relaxation produced by red wine and other plant polyphenolic compounds in thoracic aorta from male Wistar rats (12-14 wk old). Relaxation experiments were recorded isometrically on vessels precontracted with norepinephrine. Ten different chromatographic fractions (3-18 mg) isolated from red wine polyphenolic compounds (RWPC) and some available defined polyphenols (10-15 mg) were tested. Fractions enriched into either anthocyanins or oligomeric condensed tannins exhibited endothelium-dependent vasorelaxant activity (maximal relaxation in the range of 59-77%) comparable to the original RWPC. However, polymeric condensed tannins elicited a weaker vasorelaxant activity than the original RWPC (maximal relaxation ranged between 20-47%, P < 0.01). Moreover, the representative of either phenolic acid derivatives (benzoic acid, vanillic acid, gallic acid), hydroxycinnamic acid (p-coumaric acid, caffeic acid) or the flavanol [(+)-epicatechin] classes failed to induce this type of response. Among the anthocyanins, delphinidin (maximal relaxation being 89%), but not malvidin or cyanidin, showed endothelium-dependent vasorelaxation. These results show that anthocyanins and oligomeric-condensed tannins exhibited a pharmacological profile comparable to the original RWPC. These compounds may be involved in the reduction of cardiovascular mortality related to the presence of wine, fruits and vegetables in the diet.

Animals↗
PubMed1996

Flavonoids extracted from fonio millet (Digitaria exilis) reveal potent antithyroid properties.

Digitaria exilis (fonio) is a tiny variety of millet commonly eaten by inhabitants of semiarid regions. A sample of fonio collected right in the middle of a severely iodine-depleted goitrous endemic was submitted to phytochemical investigations in order to assess the potential contributory roles played by vegetable molecules to the goitrogenic processes. The total content of flavonoids amounts to 500 mg/kg of the edible whole cereal grains. Their extraction and identification fail to detect the C-glycosylflavones described in other millet varieties but point out the presence of apigenin (A = 150 mg/kg) and of luteolin (L1 = 350 mg/kg). Ten percent of A and 80% of L1 are present in free form, whereas the remaining 90% of A and 20% of L1 are bound as O-glycosylflavones. Both A and L1 aglycones manifest strong anti-thyroid peroxidase (TPO) activities, resulting in a significant reduction of the hormonogenic capacity of this enzyme. In addition, L1 significantly depresses the cyclic AMP phosphodiesterase, implying a concomitant overproduction of the thyrotropin-dependent nucleotide. These last unreported data are regarded as counteracting to some extent the TPO-mediated goitrogenic properties of L1. Since fonio is devoid of other molecules likely to interfere with the thyroid function, our results are directly and casually attributed to A and L1 found in the customary diet.

1-Methyl-3-isobutylxanthine↗
PubMed1996

Structure elucidation of three triterpene glycosides from the trunk of Argania spinosa.

The structures of three novel saponins from Argania spinosa, named arganines G, H, and J, have been elucidated by MS and NMR techniques as 3-O-beta-D-apiofuranosyl- (1-->4)-beta-D-glucopyranosyl-28-O-beta-D-glucopyranosylbayogenin (1), 3-O-beta-D-apiofuranosyl-(1-->4)-beta-D-glucopyranosyl-28-O-alpha- L- arabinopyranosylbayogenin (2), and 3-O-beta-D-apiofuranosyl-(1-->4)-beta-D-glucopyranosyl-28-O- [beta-D-apiofuranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-alpha-L - rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl]bayogenin (3), respectively.

Carbohydrate Sequence↗
PubMed1995

Triterpenoid saponins from the root of Sideroxylon foetidissimum.

Two novel triterpenoid saponins named sideroxyloside B and sideroxyloside C were isolated from the root of Sideroxylon foetidissimum. On the basis of spectroscopic and chemical methods, their structures were established as 3-O-beta-D-glucopyranosyl-28-O([beta-D-apiofuranosyl-(1-->3)-beta- D- xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->4)] [beta-D-apiofuranosyl(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-alph a-L- arabinopyranosyl) protobassic acid and 28-O([beta-D-xylopyranosyl-(1-->4)- alpha-L-rhamnopyranosyl-(1-->4)] [beta-D-apiofuranosyl-(1-->3)]-alpha-L- rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl) protobassic acid, respectively.

Carbohydrate Conformation↗
PubMed1995

Triterpenoid saponins from Mimosa pigra.

Two novel triterpene glycosides have been isolated from Mimosa pigra. The aglycone of these two compounds was identified as machaerinic acid by 1H- and 13C-nmr spectroscopy and by comparison with an authentic sample. This aglycone is substituted at position C-3 by an identical oligosaccharide chain in these glycosides, and at position C-21 by either a Z/E-methoxycinnamic [1] unit or an E-cinnamic acid [2] unit.

Carbohydrate Sequence↗
PubMed1995

Cytotoxic activity of Amaryllidaceae alkaloids.

25 Amaryllidaceae alkaloids belonging to different skeletal types were evaluated for their cytotoxic activity against one murine non-tumoral cell line (LMTK) and two human tumoral cell lines (Molt4 and HepG2) according to established protocols. Significant differences of activity related with the type of skeleton of the tested alkaloids could be observed. Pretazettine (22) was among the most active compound among the 25 tested alkaloids on the Molt4 lymphoid cells, but was inactive against HepG2 hepatoma. On the other hand, lycorenine (11) was found to be the most cytotoxic compound against HepG2 hepatoma, even though it appears to be active against Molt4 cells. Almost all of the tested alkaloids showed cytotoxic activity against fibroblastic LMTK cells. Only mesembrenone (25) showed some specificity against Molt4 cells in comparison to LMTK cells.

Alkaloids↗
PubMed1991

Seasonal Variations of the Flavonoid Content from Ginkgo biloba Leaves.

An HPLC method for the separation and the quantitative determination of flavonol glycosides, acylflavonol glycosides, and biflavones in crude leaf extracts from GINKGO BILOBA is described. The results, expressed in percentage of rutine, kaempferol P-coumaroyl glucorhamnoside, and bilobetin showed a higher amount of acylflavonol glycosides in buds, of flavonol glycosides in spring leaves, and of biflavones in autumn leaves.

Journal Article↗
PubMed1982

[Remanent efficiency of timolol in ocular hypertension (author's transl)].

In four ocular hypertensive patients (seven eyes) the lowering of intraocular pressure to a normal level persisted over a period of several months after gradual cessation of topical Timolol therapy. This remanent efficiency ("after-effect") could be used in treating ocular hypertension in order to prevent glaucoma damage.

Adult↗