Effect of two artichoke extracts (36_U and 36_EB) on rat ileum (with respect to bowel syndrome) and the peristaltic threshold.

The diagnosis and treatment of irritable bowel syndrome (IBS) are complicated. Artichoke extracts are well known to be helpful in various gastrointestinal disorders. A hydrophilic extract 36_U mainly containing luteolin-7-glycoside, luteolin-7-O-glucoside, small amounts of cynarin and luteolin increased contraction of rat ileum. This is mainly mediated by 5-HT(3) - and 5-HT(2) receptors but not 5-HT(4) receptors as can be derived by using specific antagonists such as tropisetrone, GR113806 and ketanserine. Additional mechanisms (receptors) are involved since the combination of these three antagonists was not able to fully prevent the contractive effect of extract 36_U. The lipophilic extract 36_EB mainly containing cynarin, luteolin including its glycosides, and cholorogenic acid in contrast to extract 36_U had a relaxing effect which could hardly be washed out. It was diminishing a serotonin effect and was not modified by ACh or substance P. The peristaltic threshold, i.e. the distension necessary for inducing a pathophysiologically relevant propulsion activity, is one of the important features being correlated with IBS. The peristaltic threshold was decreased by both serotonin and extract U_36. From the data it can be derived that the extract 36_U may be useful in IBS combined with obstipation when gastrointestinal contraction is necessary, whereas 36_EB may be useful in IBS combined with diarrhea when gastrointestinal relaxation is desired. Especially interesting are the influence on the threshold. It would be interesting to know which effects are mediated via cynarin and luteolin or its glycosides.

5-HT3 receptor blocking activity of arylalkanes isolated from the rhizome of Zingiber officinale.

Different extracts (ethanolic, hexane, aqueous) of ginger (rhizomes of Zingiber officinale) and the essential oil were tested using [14C]guanidinium influx into N1E-115 cells and the isolated rat ileum in order to identify their activity in inhibiting 5-HT3 receptor function. The hexane extract proved to be the most active and yielded upon bioassay-guided fractionation nine constituents: [6]-, [8]-, [10]-gingerols, [6]- and [8]-shogaols which were previously shown as active in vivo against cytotoxic drug-induced emesis; [4]-gingerol, [6]-gingerdiol, diacetyl-[6]-gingerdiol and [6]-dehydrogingerdione have not been previously tested for anti-emetic or 5-HT3 receptor antagonistic effects. Even though the latter four compounds are only minor constituents, their identification contributed towards the characterisation of a structure-activity relationship of this class of compounds. The order of potency for the nine constituents in the N1E-115 cell system was [6]-gingerdiol approximately diacetyl-[6]-gingerdiol approximately [6]-dehydrogingerdione approximately [6]-shogaol > or = [8]-shogaol approximately [8]-gingerol > [10]-gingerol > or = [6]-gingerol > [4]-gingerol.

Bioavailability and pharmacokinetics of caffeoylquinic acids and flavonoids after oral administration of Artichoke leaf extracts in humans.

Extracts from artichoke leaves are traditionally used in the treatment of dyspeptic and hepatic disorders. Various potential pharmacodynamic effects have been observed in vitro for mono- and dicaffeoylquinic acids (e.g. chlorogenic acid, cynarin), caffeic acid and flavonoids (e.g. luteolin-7-O-glucoside) which are the main phenolic constituents of artichoke leaf extract (ALE). However, in vivo not only the genuine extract constituents but also their metabolites may contribute to efficacy. Therefore, the evaluation of systemic availability of potential bioactive plant constituents is a major prerequisite for the interpretation of in vitro pharmacological testing. In order to get more detailed information about absorption, metabolism and disposition of ALE, two different extracts were administered to 14 healthy volunteers in a crossover study. Each subject received doses of both extracts. Extract A administered dose: caffeoylquinic acids equivalent to 107.0 mg caffeic acid and luteolin glycosides equivalent to 14.4 mg luteolin. Extract B administered dose: caffeoylquinic acids equivalent to 153.8 mg caffeic acid and luteolin glycosides equivalent to 35.2 mg luteolin. Urine and plasma analysis were performed by a validated HPLC method using 12-channel coulometric array detection. In human plasma or urine none of the genuine target extract constituents could be detected. However, caffeic acid (CA), its methylated derivates ferulic acid (FA) and isoferulic acid (IFA) and the hydrogenation products dihydrocaffeic acid (DHCA) and dihydroferulic acid (DHFA) were identified as metabolites derived from caffeoylquinic acids. Except of DHFA all of these compounds were present as sulfates or glucuronides. Peak plasma concentrations of total CA, FA and IFA were reached within 1 h and declined over 24 h showing almost biphasic profiles. In contrast maximum concentrations for total DHCA and DHFA were observed only after 6-7 h, indicating two different metabolic pathways for caffeoylquinic acids. Luteolin administered as glucoside was recovered from plasma and urine only as sulfate or glucuronide but neither in form of genuine glucosides nor as free luteolin. Peak plasma concentrations were reached rapidly within 0.5 h. The elimination showed a biphasic profile.

Efficacy of artichoke leaf extract in the treatment of patients with functional dyspepsia: a six-week placebo-controlled, double-blind, multicentre trial.

BACKGROUND: This study aimed to assess the efficacy of artichoke leaf extract (ALE) in the treatment of patients with functional dyspepsia (FD). METHODS: In a double-blind, randomized controlled trial (RCT), 247 patients with functional dyspepsia were recruited and treated with either a commercial ALE preparation (2 x 320 mg plant extract t.d.s.) or a placebo. The primary efficacy variable was the sum score of the patient's weekly rating of the overall change in dyspeptic symptoms (four-point scale). Secondary variables were the scores of each dyspeptic symptom and the quality of life (QOL) as assessed by the Nepean Dyspepsia Index (NDI). RESULTS: Two hundred and forty-seven patients were enrolled, and data from 244 patients (129 active treatment, 115 placebo) were suitable for inclusion in the statistical analysis (intention-to-treat). The overall symptom improvement over the 6 weeks of treatment was significantly greater with ALE than with the placebo (8.3 +/- 4.6, vs. 6.7 +/- 4.8, P < 0.01). Similarly, patients treated with ALE showed significantly greater improvement in the global quality-of-life scores (NDI) compared with the placebo-treated patients (- 41.1 +/- 47.6 vs. - 24.8 +/- 35.6, P < 0.01). CONCLUSION: The ALE preparation tested was significantly better than the placebo in alleviating symptoms and improving the disease-specific quality of life in patients with functional dyspepsia.

Toxoplasma gondii strain-specific transcript levels of SAG1 and their association with virulence.

Toxoplasma gondii isolates can be classified into mouse-virulent and -avirulent strains. Since the major surface antigen of Toxoplasma gondii, SAG1, has been shown to be important for the invasion process and might thus be involved in mouse virulence as well, we analyzed the corresponding gene of mouse-virulent and -avirulent strains. In addition to eight mismatches, mouse-virulent strains harbored five copies of an up-stream 27-bp repeat in the promotor region of SAG1 as compared with four copies in avirulent strains. Reverse-transcriptase polymerase chain reaction revealed that SAG1 expression levels in the mouse-virulent T. gondii strains were at least 4-fold those in the avirulent strains. Since SAG1 seems to mediate invasion, it is suggested that the possibly higher steady-state expression of SAG1 in mouse-virulent strains of T. gondii is associated with virulence and facilitates faster invasion by these strains in comparison with avirulent strains.

Two alleles of the gene encoding surface antigen P22 in 25 strains of Toxoplasma gondii.

A group of 25 strains of Toxoplasma gondii (4 mouse-virulent strains and 21 mouse-avirulent strains) were tested by immunoblot with 4 monoclonal antibodies (MAb) against surface antigen P22. Parasite lysates from only 12 strains were recognized by all 4 MAbs, while lysates from the remaining 13 strains (all avirulent) were not recognized by any of the 4 MAbs. Strains not recognized by the 4 MAbs were found to express an altered form of the P22 antigen. Sequencing of the P22 genes from 10 strains revealed only 2 alleles. One allele is identical to the gene from the virulent RH strain. The second allele carries 5 single nucleotide substitutions and an insertion of a GGT triplet when compared to the allele from the RH strain. Four of the 5 nucleotide changes result in amino acid substitutions and the triplet insertion results in an extra glycine residue. Four of the single base changes also result in restriction fragment length polymorphisms (RFLP). RFLP analysis of the P22 gene revealed only 2 patterns among the 25 strains. The allele of the P22 gene correlated with reactivity of the 4 MAbs to lysates of each strain. However, the allele of the P22 gene did not correlate with the virulence of each strain for mice.

Toxoplasma gondii: uptake of fetuin and identification of a 15-kDa fetuin-binding protein.

Lectin-binding studies demonstrated the presence of a 68-kDa glycoprotein in tachyzoites of Toxoplasma gondii harvested from P388D1 macrophage cell cultures but not in tachyzoites maintained in peritoneal cavities of NMRI mice. This protein was identified as the embryonic protein fetuin that regularly is contained in fetal calf serum, a component of cell-culture media. Uptake of fetuin by T. gondii was demonstrated by intracellular localization of this protein. As shown by latex agglutination and immunofluorescence, no specific binding of fetuin to the parasite's surface was detected. Using affinity chromatography on fetuin-agarose, it was demonstrated that fetuin bound specifically to a 15-kDa antigen of tachyzoites. As revealed by inhibition studies with sialic acid and the lectin Sambucus nigra agglutinin, the 15-kDa protein probably recognized glycan structures of fetuin.

[New views on the pathogenesis and diagnosis of toxoplasmosis]. / Neue Aspekte zur Pathogenese und Diagnostik der Toxoplasmose.

T. gondii is one of the most occurring human pathogenic parasites in Europe. While the majority of immunocompetent individuals with T. gondii infection do not present clinical symptoms, congenital toxoplasmosis and reactivation of a latent infection in immunocompromised patients (i. e. patients with AIDS) are of high clinical relevance. A classification of T. gondii isolates is not available so far, although it was possible to demonstrate strain differences by the use of several methods, i. e. by using monoclonal antibodies. T. gondii seems to be able to infect any mammalian cell. Host cell-derived as well as parasite-derived factors seem to be important for the contact between host cell and parasite and the subsequent internalization. Following invasion, T. gondii is located within a parasitophorous vacuole that does not fuse with lysosomes. The multiplication rate of these obligately intracellular growing parasites decreases during conversion from the tachyzoite stage to the bradyzoite stage. Finally, the bradyzoites-harbouring cysts persist for the lifetime of the host. Reconversion from bradyzoites to tachyzoites may occur in immunocompromised patients. Probably, IFN-gamma is involved in this process. In addition to serological methods, direct detection of T. gondii using PCR or demonstration of circulating antigens might be routinely used as diagnostical tools in the future. Determination of specific IgA antibodies, which can be evaluated using the immunoblot technique, seem to be important for early serological diagnosis. The use of recombinant antigens might be helpful in future diagnosis to circumvent discrepancies between serological test results which could have resulted from strain-specific differences.