Isolation of two new bioactive proanthocyanidins from Cistus salvifolius herb extract.

Two new proanthocyanidins, epigallocatechin-3-O-p-hydroxybenzoate-(4beta-->8)-epigallocatechin (1) and epigallocatechin-3-O-p-hydroxybenzoate-(4beta-->8)-epigallocatechin-3-O-gallate (2) in addition to the known compound epigallocatechin-(4beta-->6)-epigallocatechin-3-O-gallate (3), were isolated from the air-dried herb of Cistus salvifolius. The chemical structures were determined on the basis of 1D-and 2D-NMR-spectra (HSQC, HMBC) of their peracetylated derivatives, MALDI-TOF-mass spectra, and by acid-catalysed degradation with phloroglucinol. The isolated compounds 1-3 and the water extract of C. salvifolius herb were tested for their inhibitory activities against COX-1 and COX-2. Compound 2 showed the strongest inhibitory effect on COX-2 followed by compound 3, compound 1 and the water extract, while compounds 1-3 exhibited moderate in vitro inhibition against COX-1.

Is the alkaloid pipermethystine connected with the claimed liver toxicity of Kava products?

The pyridone alkaloid pipermethystine has been considered to be responsible for alleged hepatoxicity of Kava products. Investigation of a series of retain samples of finished products from the German market and self-produced extracts from root and stem material of Piper methysticum clearly showed that pipermethystine (1) is absent from all root and retain samples and extracts, with a limit of quantification of 45 ppm. As a positive control, leaves of P. methysticum showed an amount of 0.2% of 1. Thus, if there is any hepatotoxicity, compound 1 should not be the responsible constituent in the case reports with ethanolic extracts produced in Germany.

Flavan-3-ols and procyanidins from the bark of Salix purpurea L.

From a commercial aqueous ethanolic extract obtained from the bark of Salix purpurea L. the flavan-3-ols catechin, epicatechin, gallocatechin, catechin-3-O-(1-hydroxy-6-oxo-2-cyclohexene-1-carboxylic acid)-ester, the dimeric procyanidins B1, B3 and the trimeric procyanidins epicatechin-(4B-->8)-catechin-(4alpha-->8)-catechin and epicatechin-(4beta-->8)-epicatechin-(4beta-->8)-catechin were isolated. Structure elucidation was performed by NMR, CD, MS, degradation and optical rotation methods. A fraction containing higher oligomeric procyanidins was investigated by 13C NMR. Data indicate an average degree of oligomerization of 4 to 5 flavan-3-ol units with dihydroxylated B-rings and predominance of 2,3-cis-stereochemistry.

Flavonoids from Acalypha indica.

Four known kaempferol glycosides, mauritianin, clitorin, nicotiflorin and biorobin, have been isolated from the flowers and leaves of Acalypha indica. Some formerly published NMR data were corrected.

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.

Prodelphinidin trimers and characterization of a proanthocyanidin oligomer from Cistus albidus.

Two new natural prodelphinidin trimers have been isolated from the air-dried herb of Cistus albidus, epigallocatechin-(4beta --> 8)-gallocatechin-(4alpha --> 8)-catechin and epigallocatechin-(4beta --> 8)-gallocatechin-(4alpha --> 8)-gallocatechin in addition to catechin, gallocatechin and thirteen known proanthocyanidins. The structures were determined on the basis of 1D- and reverse 2D-NMR (HSQC, HMBC) experiments of their peracetylated derivatives, MALDI-TOF-MS and by acid-catalysed degradation with phloroglucinol. A more abundant higher oligomeric proanthocyanidins fraction was also isolated and its chemical constitution studied by 13C-NMR. The mean molecular weight of the higher oligomeric fraction was estimated to be 6-7 flavan-3-ol-units.

Plasma levels of hypericin in presence of procyanidin B2 and hyperoside: a pharmacokinetic study in rats.

The biological evaluation of hypericin in various test models is hampered by its poor water solubility. In former studies we have shown that the water solubility of hypericin was remarkably enhanced in the presence of the procyanidins or flavonol glycosides of Hypericum extract. The present pharmacokinetic study was designed to find out whether the improved water solubility in the presence of procyanidin B2 or hyperoside is correlated to increased plasma levels of hypericin. Plasma levels of hypericin in rats in the presence and absence of procyanidin B2 or hyperoside were determined by reversed phase HPLC using fluorimetric detection. Both compounds increased the oral bioavailability of hypericin by ca. 58 % (B2) and 34 % (hyperoside). Procyanidin B2 and hyperoside had a different influence on the plasma kinetics of hypericin; median maximal plasma levels of hypericin were detected after 360 min (C max : 8.6 ng/mL) for B2, and after 150 min (C max : 8.8 ng/mL) for hyperoside. It can be speculated that, when administered together with these compounds, a significant accumulation of hypericin in rat plasma in the presence of both polyphenols might be responsible for the observed increased in vivo activity.

Dissolution, solubility and cooperativity of phenolic compounds from Hypericum perforatum L. in aqueous systems.

The dissolution in water of phenolic constituents of St. John's wort (Hypericum perforatum L.) from a medicinal tea and a coated tablet formulation showed different dissolution profiles. In general, the flavonoid glycosides were well dissolved, followed by flavonoid aglycones and hypericin while hyperforin was only detectable at a very low level. Interestingly, hypericin exhibited much better extraction and dissolution rates than the similarly lipophilic hyperforin. When determining the octanol/water partition coefficient it became obvious that the solubility of pure hypericin in water increased upon addition of some phenolic constituents typical for Hypericum extracts. Most effective in solubilizing hypericin was hyperoside (hyperin, quercetin 3-O-beta-D-galactoside) which increased the concentration of hypericin in the water phase up to 400 fold in this model.

[Piper methysticum (kava) under discussion: observations on quality, effectiveness and safety]. / Piper methysticum (Kava) in der Diskussion: Betrachtungen zu Qualität, Wirksamkeit und Unbedenklichkeit.

Worldwide the application for a drug registration follows three basic principles: the proof of quality, efficacy and safety. In the following the applicability of these three principles on extracts from roots of the medicinal plant Kava (Piper methysticum) will be examined in the light of the current discussion of possible hepatic side effects ratio.

Procyanidins from the herb of Hypericum perforatum.

From the aqueous acetone extract of the herb of Hypericum perforatum the flavanols catechin (1) and epicatechin (2), and the procyanidins A2 (9), B1 (3), B2 (4), B3 (5), B5 (6), B7 (7) and C1 (8) were isolated. Their structures were established as their peracetate derivatives, on the basis of chemical and spectral evidence. The 13C NMR spectrum of the higher molecular weight polymer fraction revealed a 3',4'-dihydroxylated B-ring oxidation pattern and the 2,3-cis relative stereochemistry of the constituent flavan-3-ol units. The mean average molecular size of the polymers was estimated to be 4 to 5 flavan-3-ol units. The procyanidin pattern in comparison to that of Crataegus spec. is briefly discussed.

Flavonoids from Hypericum perforatum show antidepressant activity in the forced swimming test.

It has been shown recently that a flavonoid fraction (fraction II) obtained from a crude extract of Hypericum perforatum (St. John's Wort) was remarkably active in the forced swimming test (FST). Fraction II was further separated using MLCCC to give fractions IIa and IIb. Both fractions proved to be active in the FST at different dosages. Further separation of fraction IIa by preparative HPLC yielded fraction IIa1 which mainly was composed of hyperoside, isoquercitrin, miquelianin and quercitrin, and fraction IIa2 which contained small amounts of hyperoside and astilbin, while most compounds were not known. Both fractions were active after acute treatment in the FST. Isolates obtained from these fractions including hyperoside, isoquercitrin, quercitrin, miquelianin, the aglycone quercetin and astilbin, were tested for activity in the FST. Except for quercetin, quercitrin and astilbin all compounds were active. To exclude false positive results in the FST the validity was checked in open field experiments and in the FST after 12 days of daily treatment.

Inhibition of neutrophil elastase activity by cinnamic acid derivatives from Cimicifuga racemosa.

Caffeic acid, fukinolic acid as well as cimicifugic acids A, B, E and F isolated from the rhizomes of Cimicifuga racemosa (Ranunculaceae) inhibited the activity of neutrophil elastase (EC 3.4.21.37) in a dose-dependent manner. An IC50 of 93 mumol/L was determined for caffeic acid and 0.23 mumol/L for fukinolic acid. Cimicifugic acid A inhibited the enzyme with an IC50 of 2.2 mumol/L, cimicifugic acid B with 11.4 mumol/L, and cimicifugic acid F with 18 mumol/L. Cimicifugic acid E was only a very weak inhibitor.

Fukiic and piscidic acid esters from the rhizome of Cimicifuga racemosa and the in vitro estrogenic activity of fukinolic acid.

Hydroxycinnamic acid esters of fukiic acid and piscidic acid were isolated from a 50% ethanolic extract obtained from the rhizomes of Cimicifuga racemosa (Ranunculaceae). Besides 2-E-caffeoylfukiic acid (fukinolic acid), 2-E-feruloylfukiic acid (cimicifugic acid A), 2-E-isoferuloylfukiic acid (cimicifugic acid B), 2-E-feruloylpiscidic acid (cimicifugic acid E) and 2-E-isoferuloylpiscidic acid (cimicifugic acid F), free caffeic, ferulic and isoferulic acids were isolated. The estrogenic activity of fukinolic acid was shown by increased proliferation (126% at 5 x 10(-8) M) of an estrogen dependent MCF-7 cell system with reference to estradiol (120% at 10(-10) M).

Flavonol oligosaccharides from the seeds of Aesculus hippocastanum.

Nine flavonol oligosides of quercetin and kaempferol with glucose, xylose, and rhamnose as sugars were isolated from the seeds of Aesculus hippocastanum L. (Hippocastanaceae). Five of them are new compounds (2 trisaccharides, 1 bisdesmoside, a nicotinic and a indolinone hydroxyacetic acid ester of the bisdesmoside). Their structures were elucidated mainly using (1)H- and (13)C-NMR techniques.

Solubilized hypericin and pseudohypericin from Hypericum perforatum exert antidepressant activity in the forced swimming test.

It has been shown recently that the fraction IIIc of a crude extract of Hypericum perforatum, (St. John's wort) that contained both hypericin (1) and pseudohypericin (2), was remarkably active in the rats forced swimming test (FST) after Porsolt. However, neither of the naphthodianthrones isolated from this fraction were sufficiently effective when administered suspended in water. The solubility of 1 and 2 is remarkably increased in the presence of a fraction containing procyanidins, especially procyanidin B2, which is present also in the active Hypericum fraction IIIc. The cooperative effect of procyanidins significantly increased the in vivo effects of 1 and 2, which exhibited inverted U-shaped dose response curves, in the FST. The anti-immobility effect of solubilized 1 and 2 was antagonized by the dopamine antagonist sulpiride. These data indicate that naphthodianthrones are antidepressant constituents of H. perforatum and suggest that the dopaminergic system is involved in their action.

New pyrazole alkaloids from the root bark of Newbouldia laevis.

The root bark of Newbouldia laevis afforded withasomnine, 4'-hydroxywithasomnine, 4'-methoxywithasomnine, newbouldine, 4'-hydroxynewbouldine, and 4'-methoxynewbouldine. 4'-Methoxywithasomnine and 4'-methoxynewbouldine are new natural products.

Separations of flavan-3-ols and dimeric proanthocyanidins by capillary electrophoresis.

Micellar electrokinetic capillary chromatography (MECC), using a phosphate buffer pH 7.0 and sodium dodecyl sulfate as the surfactant, was found suitable for the separation of structurally similar flavan-3-ols and related dimeric proanthocyanidins. A total of 20 substances has been tested, 17 of which were successfully separated simultaneously in less than 7 minutes. Retention of the investigated compounds by the SDS micelles is affected by (i) the stereochemistry of the heterocycle of the flavan-3-ol skeleton, (ii) the molecular size, the number and position of free phenolic hydroxy groups, and (iii) the type of acyl residues attached at the C-3 hydroxy function. The method was successfully applied to the phytochemical analysis of tannin enriched extracts of Cistus incanus L. ssp. incanus and C. salvifolius L. (Cistaceae), two traditionally used medicinal plants.

Study on the composition of the volatile fraction of Hamamelis virginiana.

The volatile fractions, obtained by water distillation from the leaves and bark of Hamamelis virginiana L. were analysed in detail by GC-MS. About 175 (leaves) and 168 (bark) compounds have been identified or at least partly characterized on the basis of a computerized database (SeKoMS). The dominating substances were represented by a homologous series of alkanes, alkenes, aliphatic alcohols, related aldehydes, ketones, and fatty acid esters. Importantly, significant differences in the terpenoid and phenylpropanoid patterns of the products obtained from the bark and leaves are apparent: whereas the product of bark distillation was found to typically contain phenylpropanoids and mainly sesquiterpenoids, that obtained from the leaves included some distinct monoterpenoids detected in comparably higher amounts. The chemical composition of the volatiles, when taken together with the absence of specific accumulation sites of lipophilics, emphasizes the definition "volatile fraction" rather than "essential oil".

Effects of the total extract and fractions of Hypericum perforatum in animal assays for antidepressant activity.

A commercially available extract of the aerial parts of Hypericum perforatum, LI 160, showed pronounced activity in selected animal bioassays. These include the forced swimming test (FST) and the tail suspension test, used to determine antidepressant activity, and tests indicating activity on the central nervous system, such as body temperature and ketamine induced sleeping time. The counteracting effects of drugs known to interfere with the central dopaminergic system strongly suggested that dopamine mediated activity is important for the activity of the extract. Dose-response experiments of the total extract and of fractions rich in flavonoids and napthodianthrones produced inverted U-shaped dose response curves.