Saponins and Flavonoids from an Infusion of Herniaria hirsuta.

Stone diseases present a major health problem in the Western society, since both urinary and biliary stones occur with a relatively high prevalence of 10-12 % and 10-20 %, respectively, and demonstrate a high recurrence rate. At the moment treatment is mainly based on interventional procedures, or prophylactic and dissolution therapy. However, many of the current drugs cause severe side effects, and therefore, there is an increasing interest in natural medicines. At the moment no registered herbal medicinal products are available for treatment of gallstones. Since an infusion of Herniaria hirsuta L. has a proven efficacy against urolithiasis and cholelithiasis, its phytochemical composition has been investigated. Two previously undescribed triterpene saponins, 28-O-{[ß-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)]-[ß-D-glucopyranosyl-(1-6)]-ß-D-glucopyranosyl}-medicagenic acid and 3-O-[α-L-rhamnopyranosyl-(1 → 3)-ß-D-glucuronopyranosyl]-28-O-{[ß-D-glucopyranosyl-(1 → 3)-ß-D-xylopyranosyl-(1 → 4)]-[ß-D-apiofuranosyl-(1 → 3)]-α-L-rhamnopyranosyl-(1 → 2)-ß-D-fucopyranosyl}-medicagenic acid and three known flavonoids, quercetin-3-O-(2″-O-α-L-rhamnopyranosyl)-ß-D-glucuronopyranoside, rutin, and narcissin (isorhamnetin-3-O-rutinoside), were isolated using flash chromatography and successive semi-preparative HPLC and were well characterized by MS and 1D and 2D NMR spectroscopic techniques. These findings could contribute to the development of a standardized extract that can be used in prophylaxis and treatment of gall and kidney stones.

Development and Validation of an in vitro Experimental GastroIntestinal Dialysis Model with Colon Phase to Study the Availability and Colonic Metabolisation of Polyphenolic Compounds.

The biological effects of polyphenols depend on their mechanism of action in the body. This is affected by bioconversion by colon microbiota and absorption of colonic metabolites. We developed and validated an in vitro continuous flow dialysis model with colon phase (GastroIntestinal dialysis model with colon phase) to study the gastrointestinal metabolism and absorption of phenolic food constituents. Chlorogenic acid was used as model compound. The physiological conditions during gastrointestinal digestion were mimicked. A continuous flow dialysis system simulated the one-way absorption by passive diffusion from lumen to mucosa. The colon phase was developed using pooled faecal suspensions. Several methodological aspects including implementation of an anaerobic environment, adapted Wilkins Chalgren broth medium, 1.10(8) CFU/mL bacteria suspension as inoculum, pH adaptation to 5.8 and implementation of the dialysis system were conducted. Validation of the GastroIntestinal dialysis model with colon phase system showed a good recovery and precision (CV < 16 %). Availability of chlorogenic acid in the small intestinal phase (37 ± 3 %) of the GastroIntestinal dialysis model with colon phase is comparable with in vivo studies on ileostomy patients. In the colon phase, the human faecal microbiota deconjugated chlorogenic acid to caffeic acid, 3,4-dihydroxyphenyl propionic acid, 4-hydroxybenzoic acid, 3- or 4-hydroxyphenyl acetic acid, 2-methoxy-4-methylphenol and 3-phenylpropionic acid. The GastroIntestinal dialysis model with colon phase is a new, reliable gastrointestinal simulation system. It permits a fast and easy way to predict the availability of complex secondary metabolites, and to detect metabolites in an early stage after digestion. Isolation and identification of these metabolites may be used as references for in vivo bioavailability experiments and for investigating their bioactivity in in vitro experiments.

LC-MS analysis of 13,28-epoxy-oleanane saponins in Maesa spp. extracts with antileishmanial activity.

INTRODUCTION: Saponins are natural products that are well known for a wide range of biological activities. For saponins of Maesa balansae, selective antileishmanial activity has been described. OBJECTIVE: In view of their pharmacological interest, several Maesa species from the National Botanical Garden of Meise (Belgium) and wild-grown plants from Vietnam were screened for their antileishmanial potential and saponin content. METHODOLOGY: Different parts of the plants (mainly leaves and twigs) were collected, dried and extracted. Plant extracts were evaluated by liquid chromatography/mass spectrometry (LC-MS) using electrospray ionisation in the negative ion mode and their saponin content was compared with those of Maesa balansae (maesabalides) and Maesa lanceolata (maesasaponins). RESULTS: Several Maesa species (M. ambigua, M. argentea, M. brevipaniculata, M. japonica and M. perlarius) showed potent antileishmanial activity (<0.1 microg/mL) and indeed contained known maesasaponins and maesabalides. However the leaves of M. argentea also revealed two new compounds. Two saponins with [M - H]- ions at m/z 1465 and 1477 were characterised. Their mass spectrometric fragmentation pattern revealed a structure that was the same or closely related to maesasaponin V.3 and VI.2, respectively, but had a glycan part with one additional hexose residue. CONCLUSION: Several known as well as new saponins from Maesa species active against leishmaniasis were characterised using LC-MS.

Structural characterization of flavonol di-O-glycosides from Farsetia aegyptia by electrospray ionization and collision-induced dissociation mass spectrometry.

This study reports the application of mass spectrometric methods to characterize unknown flavonoids of the herb Farsetia aegyptia Turra (Crucifereae). High-performance liquid chromatography was performed in combination with UV-photodiode array detection (LC/UV-DAD) and electrospray ionization mass spectrometry (LC/ESI-MS) in both positive and negative ion modes. Collision-induced dissociation (CID) mass spectral data were obtained off-line by nanospray (nano-ESI) analysis, which provided a wealth of information and led to the structural proposal of the flavonol di-O-glycosides present in the herb extract. In addition to the mass spectral data, we also report NMR data for the major compound which allowed the completion of its structural elucidation. The Farsetia aegyptia Turra herb extract was found to contain three flavonol di-O-glycosides containing a monosaccharidic residue linked to the 3-O position and a disaccharidic residue linked to the 7-O position; the major compound was characterized as the new flavonoid, isorhamnetin 3-O-alpha-L-arabinoside 7-O-[beta-D-glucosyl-1 --> 2]-alpha(L)rhamnoside. Different types of CID spectra, i.e., low-energy [M+H]+, [M+Na]+ and [M--H]- spectra as well as high-energy [M+Na]+ spectra, were evaluated with respect to their utility to locate the O-linked saccharidic residues in flavonol di-O-glycosides and to determine the sequence in the disaccharidic part. In agreement with previously published data, the 3-O-glycosyl residue was more readily lost from the protonated molecule than the 7-O-glycosyl residue. The opposite behavior was noted for the fragmentation of the deprotonated and sodiated molecules. Radical ions were observed in the high-energy [M+Na]+ CID spectra which provided supporting information on the glycosylation positions.

Anthranoid compounds with antiprotozoal activity from Vismia orientalis.

A phytochemical investigation of the 80% ethanolic extract of stem bark of Vismia orientalis Engl. (Guttiferae or Clusiaceae), a plant used in traditional medicine in Tanzania, resulted in the isolation and spectroscopic characterisation of 3-geranyloxy-6-methyl-1,8-dihydroxyanthraquinone, emodin, vismione D and bianthrone A1. Vismione D exhibited a broad range of antiprotozoal activities against Trypanosoma brucei rhodesiense and T. cruzi (IC50 < 10 micrograms/mL), Leishmania donovani (IC50 0.37 micrograms/mL) and Plasmodium falciparum strain K1 (IC50 1.0 microgram/mL). However, it was also slightly cytotoxic against human L6 cells (IC50 4.1 micrograms/mL). Emodin showed antileishmanial activity (IC50 2.0 micrograms/mL), while its IC50 against L6 cells was 20.3 micrograms/mL. Other antiprotozoal activities observed for emodin against both Trypanosoma species and P. falciparum, for bianthrone A1 against T. b. rhodesiense and P. falciparum, and for 3-geranyloxy-6-methyl-1,8-dihydroxyanthraquinone against T. b. rhodesiense, L. donovani and P. falciparum were in the range of 10 to 50 micrograms/mL. None of the compounds showed antibacterial or antiviral (including also HIV) activity.

Fast high-performance liquid chromatography method for quality control of soy extracts.

Soy extracts contain a mixture of isoflavones belonging to the group of phytoestrogens. In the quality control of soy the amount of isoflavones, both aglycones and glycosides, is usually determined by means of reversed-phase HPLC-UV. On conventional C18-material columns, long analysis times are required in order to separate this complex mixture. In order to speed up analysis, the separation was optimized using two linked monolithic silica-based reversed-phase C18 columns. A spectacular decrease of the analysis time, i.e. almost three-fold, was achieved by applying a flow rate of 3-4 ml/min without loosing any separation efficiency. This analysis method for determination of isoflavones in soy extracts in less than 25 min was fully validated according to the ICH guidelines.

Complement-inhibiting iridoids from Morinda morindoides.

Morinda morindoides (Baker) Milne-Redhead (syn. Gaertnera morindoides Bak.) is one of the most popular medicinal plants in the Democratic Republic of Congo. In relation to its traditional use against rheumatic pains, fractionation of both the EtOAc- and the n-BuOH-soluble fraction of the 80% MeOH extract of the leaves, guided by the anticomplementary activity on the classical activation pathway, yielded eight novel iridoids (1-8), all containing a spirolactone functionality. Their structure was elucidated using spectroscopic methods. Gaertneroside 1, acetylgaertneroside 2, and gaertneric acid 5 were found to inhibit the activation of the classical pathway of the complement system, with IC(50) values between 58 and 69 microM. In addition to the biologically active flavonoids reported before from the same plant, these complement-inhibiting iridoids may contribute at least in part to the traditional use against rheumatic pains.

Structural characterization of chromone C-glucosides in a toxic herbal remedy.

Two novel compounds, 8-C-D-glucopyranosyl-7-hydroxy-5-methylchromone-2-carboxylic acid and a 2-O'-p-coumaroyl derivative thereof, were identified in a herbal tea that caused severe vomiting in a South African patient who had taken the traditional remedy to clean his stomach. For structural characterization, electrospray (ES) ionization in combination with collision-induced dissociation (CID) and tandem mass spectrometry (MS/MS) were used, as well as UV and nuclear magnetic resonance (NMR) spectroscopy. Specific ions or neutral losses generated under conditions of ES-MS/CID/MS permitted the establishment of structural features such as the free carboxyl group, the C-hexosidic part and the p-coumaroyl group. NMR spectroscopy was necessary to support the structure of the chromone-type aglycone and the glucosidic parts. Since the compounds are structurally related to aloesin and aloeresin A, which are chemotaxonomic markers of Aloe species, and have not been previously reported, we propose that they were formed by oxidative degradation during preparation of the herbal tea from an Aloe species or during its storage.

Optimization of a liquid chromatography method based on simultaneous electrospray ionization mass spectrometric and ultraviolet photodiode array detection for analysis of flavonoid glycosides.

Different reversed-phase liquid chromatography (LC) columns of conventional dimensions were coupled to an ultraviolet photodiode array detector (UV-DAD) and a magnetic sector-type spectrometer, equipped with an electrospray ionization (ESI) source, by a laboratory-made flow splitter. A mixture of three flavonoid-O-glycosides was employed to examine the effects of the solvent composition, the flow rate, the stationary phase, the pH and the organic acid added, on the chromatographic separation, the UV-DAD detection, the ESI process and the entire LC system with ESI-MS and UV-DAD detection. In the positive ion mode, methanol containing 1% acetic acid was by far the most sensitive in ESI-MS analysis, whereas an acetonitrile/water mobile phase containing 0.5% formic acid was proved to give the best sensitivity in LC/ESI-MS/UV-DAD analysis. In the negative ion mode, the highest sensitivity was obtained with a mobile phase containing 0.1% formic acid, while addition of bases decreased the sensititvity. The optimal flow rate was higher in negative ESI (20-50 micro L/min) than in positive ESI (5 micro L/min), and the percentage of organic phase had an influence on the sensitivity of ESI-MS detection. With regard to the selection of a suitable C(18) reversed-phase LC column, a column which is well end-capped is to be preferred, because residual silanol groups appear to impair the separation of flavonoid glycosides. The optimized LC/ESI-MS/UV-DAD method was applied to a commercial Crataegus extract, which is used in phytomedicine to treat cardiovascular problems and is known to be rich in flavonoids. It is demonstrated how UV spectra and first-order ESI mass spectra allow a fast characterization of flavonoids, even if reference compounds are not available or at hand.

Direct stereochemical assignment of hexose and pentose residues in flavonoid O-glycosides by fast atom bombardment and electrospray ionization mass spectrometry.

Mass spectrometric methods have been developed which allow the direct stereochemical assignment of terminal monosaccharide residues in flavonoid O-glycosides without the need for chemical hydrolysis. Standards containing a glucose, galactose, mannose, xylose, arabinose or apiose residue were examined because these monosaccharides are by far the most commonly encountered in flavonoid glycosides. Following acetylation, the major peracetylated sugar related fragments, generated by fast atom bombardment (FAB) or electrospray ionization (ESI), were selected for collisional activation employing a broad range of collision energies. Both FAB and ESI proved to be useful as ionization techniques. Stereoselective fragmentation was achieved and allowed us clearly to differentiate and characterize isomeric monosaccharide residues. The method developed was successfully applied to an unknown flavonoid containing a terminal pentose and hexose residue which was isolated from Farsetia aegyptia.

In vitro inhibition of [3H]-angiotensin II binding on the human AT1 receptor by proanthocyanidins from Guazuma ulmifolia bark.

A bioassay-guided fractionation of the 70% acetone extract of the bark of Guazuma ulmifolia Lam. on the inhibition of angiotensin II binding to the AT 1 receptor led to the isolation and identification of bioactive oligomeric and polymeric proanthocyanidins consisting mainly of (-)-epicatechin units. The displacement of [3H]-angiotensin II binding was dose-dependent and correlated with the degree of polymerization of the different fractions containing proanthocyanidins. A strong displacement was seen for the residual fraction suggesting that the most active substances corresponding to the highly polymerized proanthocyanidins. Angiotensin II AT 1 receptor binding might be considered as a potentially interesting biological activity of proanthocyanidins contributing to the very broad spectrum of biological activities of the condensed tannins.

Inhibitory activity on binding of specific ligands to the human angiotensin II AT(1) and endothelin 1 ET(A) receptors: bioactive benzo[c]phenanthridine alkaloids from the root of Bocconia frutescens.

A bioassay-guided fractionation of the 80 % ethanolic extract from Bocconia frutescens L. roots, showing a dose-dependent inhibitory effect towards both [(3)H]-angiotensin II and [(3)H]-BQ-123 binding to the human angiotensin II AT 1 and endothelin 1 ET(A) receptors, led to an alkaloidal subfraction as the only responsible fraction for the activity of the whole extract. Among the alkaloids present in this fraction sanguinarine and chelerythrine were significant inhibitors of [(3)H]-angiotensin II binding (hAT 1 receptor), with IC(50) values within the micromolar range. On the contrary, the [(3)H]-BQ-123 binding (ET(A) receptor) was only weakly inhibited. Moreover, other members of the isoquinoline alkaloid family such as chelidonine and some protoberberine alkaloids exhibited no affinity for the two receptors. The present work shows the possible structure-activity relationship for these benzophenanthridine alkaloids on a screening bioassay using both stably transfected Chinese hamster ovary (CHO) and the human neuroblastoma SK-N-MC cells. Furthermore, the ability of these compounds to block AT(1) and/or ET(A) receptors may provide some justification for the traditional use of Bocconia frutescens L. to control hypertension.

Antiviral and antioxidant activity of flavonoids and proanthocyanidins from Crataegus sinaica.

The antiviral and antioxidant activity of some fractions and of a series of flavonoids and proanthocyanidins obtained from Crataegus sinaica (Rosaceae) was evaluated. The O-glycosidic flavonoids and the oligomeric proanthocyanidins exhibited significant inhibitory activity against herpes simplex virus type 1 (HSV-1), which was shown to be due to an extracellular mechanism for procyanidin C-1. Procyanidin C-1 also had the highest antioxidant activity in both the microsomal lipid peroxidation and the hydroxyl radical scavenging assay. In addition to the previously reported phenolic compounds, the pentacyclic triterpenoid ursolic acid (1) and a tetrameric (2) and pentameric procyanidin (3) are reported for the first time.

Herbal remedy-associated acute renal failure secondary to Cape aloes.

Use of traditional herbal remedies is common in Africa, and many patients who visit traditional healers do not need to resort to Western medicine. Acute renal failure is one of the most serious complications resulting from the use of traditional remedies, however, which accounts for 35% of all cases of acute renal failure in Africa. Traditional remedies rarely have been analyzed, and little is known about their nephrotoxicity. We report a case of a 47-year-old man from Soweto, South Africa, who developed acute oliguric renal failure and liver dysfunction after ingestion of an herbal remedy. The patient's renal function recovered slowly, and dialysis was discontinued after several weeks, although serum creatinine did not return to the normal range. Mass spectrometric and chromatographic analysis of the herbal remedy used by the patient revealed the presence of Cape aloes, a previously described nephrotoxin.