In vitro and in vivo antiplasmodial activity of extracts and isolated constituents of Alstonia congensis root bark.

ETHNOPHARMACOLOGICAL RELEVANCE: An aqueous decoction of root bark of Alstonia congensis Engl. (Apocynaceae) is used in several African countries to treat various ailments including malaria. MATERIALS AND METHODS: Extracts of different polarity and isolated constituents were tested in vitro for their antiplasmodial activity against the chloroquine-resistant strain Plasmodium falciparum K1 and the chloroquine-sensitive strain P. falciparum NF54A19A, as well as for their cytotoxic effects againt MRC-5 cells (human lung fibroblasts). Extracts and fractions were evaluated in vivo against the chloroquine-resistant strain P. yoelii N67 and the chloroquine-sensitive strain P. berghei berghei ANKA. RESULTS: The aqueous extract, the 80% methanol extract and the alkaloid-enriched extract exhibited strong antiplasmodial activity against P. falciparum K1 with IC50 values < 10 µg/ml and against P. falciparum NF54 A19A with IC50 values < 0.02 µg/ml. In vivo against P. yoelii N67, at the highest oral dose of 400 mg/kg body weight, all extracts produced 70-73% chemosuppression, while against P. berghei berghei, more than 75% chemosuppression was observed. With regard to the isolated constituents, boonein was inactive in vitro against P. falciparum K-1 (IC50 > 64 µM), while echitamine, 6,7-seco-angustilobine B and ß-amyrin exhibited moderate activity (IC50 < 30 µM). Against P. falciparum NF54 A19A, boonein was inactive (IC50 > 64 µM), while echitamine, 6,7-secoangustilobine and ß-amyrin showed moderate IC50 values of 11.07, 21.26 and 40.70 µM, respectively. CONCLUSION: These results demonstrated that all extracts from A. congensis root bark possessed antiplasmodial activity in vitro and in vivo. They can be used as raw materials for the preparation of ameliorated remedies for the treatment of uncomplicated malaria. The observed antiplasmodial activity may be due in part to the presence of indole alkaloids.

The value of central-African traditional medicine for lead finding: Some case studies.

UNLABELLED: Ethnoparmaological relevance: One of the possible methodologies for the discovery of novel drugs is the screening of selected plant extracts for a broad array of pharmacological activities. MATERIALS AND METHODS: The selection based on enthnomedicinal uses, combined with a follow-up of existing literature on the plants' chemotaxonomic properties, would seem to be the most cost-effective strategy for finding active plant extracts. A bioassay-guided fractionation of the active extracts should subsequently lead to the isolation and identification of the active lead constituent(s). RESULTS AND DISCUSSION: Taking into account the enormous number and the amazing structural diversity of the currently known plant constituents, one might hope that promising model compounds with new structures and/or novel mechanisms of action might be found. In order, however, to optimize such a natural product drug discovery methodology, dereplication and selectivity of activity should be included in the screening system. Dereplication by which known compounds can rapidly be identified from a partially purified mixture prevents a research group from wasting resources by rediscovering known compounds. The use of single-target specific bioassays such as tests on isolated enzymes or on receptor-binding, or multiple target functional bioassays on isolated organs or intact cells must allow at an early stage to isolate compounds with specific pharmacological properties. CONCLUSIONS: In this publication, several examples of bioassay-guided isolation and identification of pharmacologically active lead compounds from plants used in Central-African traditional medicine by our research group will be presented and discussed.

Antimalarial efficacy of a quantified extract of Nauclea pobeguinii stem bark in human adult volunteers with diagnosed uncomplicated falciparum malaria. Part 2: a clinical phase IIB trial.

According to the promising results of the Phase I and Phase IIA clinical trials with the herbal medicinal product PR 259 CT1 consisting of an 80 % ethanolic extract of the stem bark of Nauclea pobeguinii containing 5.6 % strictosamide, a Phase IIB study was conducted as a single blind prospective trial in 65 patients with proven Plasmodium falciparum malaria to evaluate the effectiveness and safety of this herbal drug. The study was carried out simultaneously using an artesunate-amodiaquine combination (Coarsucam®) as a positive control. This combination is the standard first-line treatment for uncomplicated malaria recommended by the National Programme of Malaria Control in the Democratic Republic of Congo (DR Congo). With regard to PR 259 CT1, patients were treated with a drug regimen of two 500-mg capsules three times daily for three days in the inpatient clinic, followed by out-patient treatment of one 500-mg capsule three times daily during the next four days; the positive control group received two tablets containing 100 mg artesunate and 270 mg amodiaquine (fixed-dose) once daily during three consecutive days. Antimalarial responses were evaluated according to the WHO 2003 guideline for a 14-day test. The results from the physical and laboratory examinations did not show any significant changes in values of vital signs, ECG, biochemical, and haematological parameters. The study showed a significant decreased parasitaemia in patients treated with PR 29 CT1 and artesunate-amodiaquine with adequate clinical parasitological responses (APCR) at day 14 of 87.9 and 96.9 %, respectively. The former product was better tolerated than the latter since more side effects were observed for the artesunate-amodiaquine combination. These results indicated that PR 259 CT1 can be considered as a promising candidate for the development of a herbal medicine for the treatment of uncomplicated falciparum malaria.

Antimalarial efficacy of a quantified extract of Nauclea pobeguinii stem bark in human adult volunteers with diagnosed uncomplicated falciparum malaria. Part 1: a clinical phase IIA trial.

The aim of this phase IIA clinical trial was to assess the efficacy of an 80 % ethanolic quantified extract (containing 5.6 % strictosamide as the putative active constituent) from Nauclea pobeguinii stem bark denoted as PR 259 CT1 in a small group of adult patients diagnosed with uncomplicated falciparum malaria. Results obtained from a phase I clinical trial on healthy male volunteers indicated that the oral administration during meals of two 500 mg capsules three times daily (each eight hours) during seven days was well tolerated and showed only mild and self-resolving adverse effects. This PR 259 CT1 drug regimen was obtained by mathematical conversion of animal doses obtained in several in vivo studies in mice to human equivalent doses as in falciparum malaria patients. The phase IIA study was an open cohort study in eleven appraisable adult patients suffering from proven Plasmodium falciparum malaria. The study was specifically designed to assess the efficacy of PR 259 CT1 administered with a dose regimen of two 500 mg capsules three times daily for three days, followed by outpatient treatment of one 500 mg capsule three times daily for the next four days, in order to prove that this therapeutic dose, which was calculated from animal doses, was effective to treat adult malaria patients and consequently useful for a future Phase IIB clinical trial. This study would then substitute a dose-escalating trial, which in general is used to find the appropriate dose for clinical studies. The phase IIA clinical trial was carried out according to the WHO 2003 14-day test, and the results revealed that all eleven patients were completely cleared of parasitemia and fever on days 3, 7, and 14 except for one patient, who experienced a recurrence of parasitemia at days 7 until 14. Besides this adequate clinical and parasitological response (ACPR), this trial also demonstrated that PR 259 CT1 was well tolerated with only mild and self-resolving adverse effects including fatigue and headache, which were in accordance with those found in the phase I clinical trial. Moreover, all symptoms progressively disappeared, and no symptoms were observed on day 14. Although the number of patients included in this study was rather limited, the statistical analysis nevertheless suggested the efficacy and tolerability of PR 259 CT1, which indicated that this herbal medicinal product might be considered as a putative candidate for a large scale clinical trial.

The quantification of ellagic acid in the crude extract of Phyllanthus amarus Schum. & Thonn. (Euphorbiaceae).

INTRODUCTION: Phyllanthus amarus Schum. & Thonn. (Euphorbiaceae), already well known for its antiviral, antihyperglycaemic and antihepatotoxic effects, is also investigated for its antimalarial activity. The major constituent of the crude extract of the whole plant was isolated and identified in this research to be ellagic acid, for which antiplasmodial activity already has been reported. OBJECTIVE: Because of the potential of the plant and the interesting properties of ellagic acid, an analytical method can be useful for the standardisation of the extracts to allow further biological and pharmacological investigations. In order to obtain an easily performable and inexpensive method, an HPLC analysis was developed and validated. METHODOLOGY: The samples were dissolved in DMSO, ultrasonicated for 15 min, and diluted with 50% methanol. Analysis was performed using water and methanol containing 0.06% TFA and the peaks were detected at 254 nm. RESULTS: Ellagic acid showed a linear relationship in the range of 1.74-20.91 µg/mL and a single-point calibration was allowed. The method was shown to be precise with respect to time (RSD of 1.84%, 3 days, n = 6) and concentration (RSD of 2.54%, 3 levels, n = 6). The overall mean content of ellagic acid was 2.06%. A recovery experiment was performed and it showed an accuracy of 100.4%. CONCLUSION: Based on the obtained results, it can be concluded that the newly developed method is suitable for its purpose, namely the determination of ellagic acid in the crude extract of P. amarus.

Quantification of xanthohumol, isoxanthohumol, 8-prenylnaringenin, and 6-prenylnaringenin in hop extracts and derived capsules using secondary standards.

Hop is a well-known and already frequently used estrogenic phytotherapeutic, containing the interesting prenylflavonoids, xanthohumol (XN), isoxanthohumol (IXN), 8- and 6-prenylnaringenin (8-PN and 6-PN). Since the use of secondary standards can form a solution whenever the determination is required of certain components, not commercially available or too expensive, it was decided to develop an accessible HPLC-DAD method for the determination of these prenylflavonoids. The amounts were determined in hop extract and capsules, using quercetin and naringenin as secondary standards. After optimization of the sample preparation and HPLC conditions, the analysis was validated according to the ICH guidelines. The response function of XN, 8-PN, quercetin and naringenin showed a linear relationship. For the determination of XN, a calibration line of at least three concentrations of quercetin has to be constructed. The correction factors for XN (quercetin) and for 8-PN (naringenin) were validated and determined to be 0.583 for XN, and 1.296 for IXN, 8-PN and 6-PN. The intermediate precision was investigated and it could be concluded that the standard deviation of the method was equal considering time and concentration (RSD of 2.5-5%). By means of a recovery experiment, it was proven that the method is accurate (recoveries of 96.1-100.1%). Additionally, by analysing preparations containing hop extracts on the Belgian market, it was shown that the method is suitable for its use, namely the determination of XN, IXN, 8-PN and 6-PN in hop extract and capsules, using quercetin and naringenin as secondary standards.

Antimalarial activity and toxicity evaluation of a quantified Nauclea pobeguinii extract.

AIM OF THE STUDY: To evaluate the in vitro and in vivo antiplasmodial activity and toxicity of the aqueous and 80% EtOH extract of the stem bark of Nauclea pobeguinii (Pob. Ex. Pell.) Petit (Rubiaceae), a plant used in traditional medicine in DR Congo against malaria. MATERIALS AND METHODS: The aqueous and 80% EtOH extract from N. pobeguinii stem bark, and its constituents (5S)-5-carboxystrictosidine, 19-O-methylangustoline, 3-O-beta-fucosylquinovic acid, 3-ketoquinovic acid and strictosamide, were evaluated for their in vitro activity against Plasmodium falciparum (chloroquine-sensitive Ghana-strain). The 80% EtOH extract, containing 5.6% strictosamide, was evaluated in vivo in the 4-day P. berghei mouse model, and in the P. yoelii N67 model. RESULTS: All compounds were inactive or only moderately active in vitro. The aqueous and 80% EtOH extract displayed moderate in vitro activity with IC(50) values of 44 and 32 microg/mL, respectively, without apparent cytotoxicity on MRC-5 cells (CC50>64 microg/mL). Daily oral dosing of the 80% EtOH extract, at 300 mg/kg, resulted in 86% reduction of parasitaemia in the 4-day P. berghei mouse model, and 75% reduction in the P. yoelii N67 model. Prolonging oral dosing to 2 x 5 days, with an interval of 2 days, and oral administration of the 80% EtOH extract at 300 mg/kg induced 92% reduction of parasitaemia, and a mean survival time of 17 days. Strictosamide, the putative active constituent, may be metabolically activated in the gastrointestinal tract after oral administration. Levels of creatinin, urea, ALAT and ASAT remained unchanged after treatment. No acute toxicity was observed in mice after a single 2g/kg oral dose, nor after 4 weekly doses. No significant macroscopic or microscopic lesions were observed in heart, lung, spleen, kidney, liver, large intestine and brain. CONCLUSIONS: These results can partly support and justify the use of N. pobeguinii in traditional medicine in the DR Congo for the treatment of uncomplicated malaria.

Phytochemical and biological investigations of Elaeodendron schlechteranum.

AIM OF THE STUDY: Elaeodendron schlechteranum (Loes.) Loes. is a shrub or tree belonging to the family Celastraceae. In Tanzania, in addition to ethnopharmacological claims in treating various non-infectious diseases, the root and stem bark powder is applied on septic wounds, and the leaf paste is used for treatment of boils and carbuncles. The aim of this study was to identify the putative active constituents of the plant. MATERIALS AND METHODS: Dried and powdered root bark was extracted and subjected to bioassay-guided fractionation, based on antibacterial, antiparasitic and anti-HIV activity. Isolated compounds were identified by spectroscopic methods, and evaluated for biological activity. RESULTS AND CONCLUSIONS: Bioassay-guided isolation led to the identification of tingenin B (22beta-hydroxytingenone) as the main antibacterial constituent. It was active against Bacillus cereus, Staphylococcus aureus and Escherichia coli (IC(50)<0.25 microg/mL). Furthermore, antiparasitic activity was observed against Trypanosoma cruzi (IC(50)<0.25 microg/mL), Trypanosoma brucei (<0.25 microg/mL), Leishmania infantum (0.51 microg/mL), and Plasmodium falciparum (0.36 microg/mL). Tingenin B was highly cytotoxic to MRC-5 cells (CC(50) 0.45 microg/mL), indicating a poor selectivity. Two inactive triterpenes, 3beta,29-dihydroxyglutin-5-ene and cangoronine methyl ester were also obtained. Phytochemical investigation of the anti-HIV active fractions led to the isolation and identification of three phenolic compounds, namely 4'-O-methylepigallocatechin, 4'-O-methylgallocatechin, and a new procyanidin dimer, i.e. 4',4'''-di-O-methyl-prodelphinidin B(4) or 4'-O-methylgallocatechin-(4alpha-->8)-4'-O-methylepigallocatechin. However, none of these showed anti-HIV activity.

Screening of Tanzanian medicinal plants against Plasmodium falciparum and human immunodeficiency virus.

Medicinal plants used to treat infectious diseases in Bunda district, Tanzania, were screened for activity against Plasmodium falciparum and Human Immunodeficiency Virus Type 1 (HIV-1, IIIB strain) and Type 2 (HIV-2, ROD strain). Antiplasmodial activity was observed for the 80 % MeOH extract of Ormocarpum kirkii (root; MIC = 31.25 microg/mL), Combretum adenogonium (leaves), Euphorbia tirucalli (root), Harrisonia abyssinica (root), Rhynchosia sublobata (root), Sesbania sesban (root), Tithonia diversifolia (leaves), and Vernonia cinerascens (leaves; MIC value of 62.5 microg/mL). With regard to HIV, 80 % MeOH extracts of Barleria eranthemoides (root), Combretum adenogonium (leaves and stem bark), Elaeodedron schlechteranum (stem bark and root bark), Lannea schweinfurthii (stem bark), Terminalia mollis (stem bark and root bark), Acacia tortilis (stem bark), Ficus cycamorus (stem bark) and Indigofera colutea (shoot), as well as H2O extracts from Barleria eranthemoides (root), Combretum adenogonium (leaves and stem bark), and Terminalia mollis (stem bark and root bark) exhibited IC50 values below 10 microg/mL against HIV-1 (IIIB strain). The highest anti-HIV-1 activity value was obtained for the B. eranthemoides 80 % MeOH root extract (IC50 value 2.1 microg/mL). Only a few extracts were active against HIV-2, such as the 80 % MeOH extract from Lannea schweinfurthii (stem bark) and Elaeodedron schlechteranum (root bark), showing IC50 values < 10 microg/mL.

A new monoterpene alkaloid and other constituents of Plumeria acutifolia.

Phytochemical investigation of the methanolic extract of Plumeria acutifolia (Apocynaceae) leaves has led to the isolation and identification by spectroscopic means of a new monoterpene alkaloid, (R)-4'-((S)-1-hydroxyethyl)-5,6-dihydro-5' H-spiro[cyclopenta[C]pyridine-7,2'-furan)-5'-one, for which the name plumerianine was adopted, the iridoid 15-demethylplumeride, and three known triterpenes, i. e., lupeol, uvaol and ursolic acid.

Screening of some Tanzanian medicinal plants from Bunda district for antibacterial, antifungal and antiviral activities.

Extracts from 50 plant parts obtained from 39 different plants belonging to 22 families used to treat infectious diseases in Bunda district, Tanzania, were screened against twelve microorganisms, including the bacteria Bacillus cereus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Salmonella typhimurium, the fungi Aspergillus niger, Candida albicans, and the viruses Herpes Simplex Virus type 1, Vesicular Stomatitis Virus T2, Coxsackie B2 and Semliki Forest A7. The highest activity was obtained for the n-hexane extract of Elaeodendron schlechteranum root bark against the Gram-positive bacteria Bacillus cereus (MIC 0.97 microg/ml and MBC 1.95 microg/ml) and Staphylococcus aureus (MIC 3.90 microg/ml and MBC 31.25 microg/ml). Gram-negative bacteria were less sensitive. Only Balanites aegyptiaca stem bark exhibited a high antifungal activity against Candida albicans (MIC 125 microg/ml and MFC 250 microg/ml). Extracts from four plants; Lannea schweinfurthii, Combretum adenogonium, Ficus sycomorus and Terminalia mollis showed strong antiviral activity with RF values of 10(3) and 10(4) against Herpes Simplex Virus type 1 at various concentrations. Our results support, at least in part, the use of most plants as claimed by traditional healers/informants especially against the Gram-positive bacteria Bacillus cereus and Staphylococcus aureus.

Determination of saponins in Maesa lanceolata by LC-UV: development and validation.

Triterpene saponins are a class of plant natural products with a wide range of bioactivities, which makes them an interesting research subject. The small tree Maesa lanceolata, growing in African countries, is used in traditional medicine against various diseases. In previous work a triterpenoid saponin mixture was isolated from the leaves of M. lanceolata and the compounds were identified as closely related oleanane type triterpenes [Apers, S., Foriers, A., Sindambiwe, J.B., Vlietinck, A., Pieters, L., 1998. Separation of a triterpenoid saponin mixture from Maesa lanceolata: semi preparative reversed-phase wide pore high performance liquid chromatography with temperature control. J. Pharm. Biomed. Anal. 18, 737; Apers, S., De Bruyne, T.E., Claeys, M., Vlietinck, A.J., Pieters, L.A.C., 1999. New acylated triterpenoid saponins from Maesa lanceolata. Phytochemistry 52, 1121]. The compounds showed virucidal, haemolytic, molluscicidal and antiangiogenic activity [Apers, S., Baronikova, S., Sindambiwe, J.B., Witvrouw, M., De Clercq, E., Vanden Berghe, D., Van Marck, E., Vlietinck, A., Pieters, L., 2001. Antiviral, haemolytic and molluscicidal activities of triterpenoid saponins from Maesa lanceolata: establishment of structure-activity relationships. Planta Med. 67, 528; Apers, S., Bürgermeister, J., Baronikova, S., Vermeulen, P., Paper, D., Van Marck, E., Vlietinck, A.J., Pieters, L.A.C., 2002. Antiangiogenic activity of natural products: in vivo and in vitro test models. J. Pharm. Belg. 57 (Hors-série 1), 47]. Here we report the development of an extraction and quantification method to analyse saponin compounds in roots and leaves of M. lanceolata. After a purification step using C(18) solid phase extraction (SPE) cartridges, the samples were analysed on a LC-UV/MS system. The identification of the peaks from the different saponins was confirmed based on the retention time and mass spectrum. The quantification was performed using the UV signals. The standard oleanolic acid curve was linear over a concentration range of 2.8-140.0mug/mL. The recovery from the leaves was 94.5%. The precision of the method with respect to time and concentration was acceptable, with relative standard deviation (RSD%) values of 4.9 and 4.3, respectively.

Ethnopharmacological survey of the Bunda district, Tanzania: plants used to treat infectious diseases.

An ethnobotanical study was carried out in six villages in the Bunda district, Mara Region, Tanzania, where the use of plants still has a special meaning to the society, in the treatment of various diseases. Information was obtained from the traditional healers and other experienced persons, having some knowledge on medicinal plants. Fifty-two plants were reported for use in the treatment of various infectious diseases. These plants belong to 29 families, with Papilionaceae being the most represented. Leaves ranked the highest, especially for use in topical preparations. Oral administration was the most frequently used route of administration. Twenty-one percent of the recorded plants were reported for treating venereal diseases, with syphilis and gonorrhea being the most commonly mentioned. Information providers requested feedback with regard to the plants proven scientifically to be toxic in order to avoid risks while offering their services. From this work it was found out that, people in this area commonly use medicinal plants with trust they have built on the curative outcome witnessed. As the first ethnobotanical study in Bunda district recording 52 plants in a small area covered, publication of this work is expected to open up more studies to record many useful medicinal plants unfolded.

Study of potential systemic oxidative stress animal models for the evaluation of antioxidant activity: status of lipid peroxidation and fat-soluble antioxidants.

Although many compounds have already been tested in-vitro to determine their antioxidant profile, it is necessary to investigate the in-vivo effect of potential antioxidants. However, representative models of systemic oxidative stress have been poorly studied. Here, different potential systemic oxidative stress animal models have been investigated. These included a vitamin E-deficient rat, a diabetic rat and an atherosclerotic rabbit model. Plasma/serum malondialdehyde was measured as a parameter of oxidative damage. Plasma/serum fat-soluble antioxidants were determined as markers of antioxidant defence. We demonstrated that vitamin E-deficient rats were not suitable as a model of systemic oxidative stress, whereas diabetic and atherosclerotic animals showed increased systemic oxidative damage, as reflected by significantly augmented plasma/serum malondialdehyde. Moreover, plasma coenzyme Q9 increased by 80% in diabetic rats, confirming systemic oxidative stress. In view of these observations and economically favouring factors, the diabetic rat appeared to be the most appropriate systemic oxidative stress model. These findings have provided important information concerning systemic oxidative stress animal models for the in-vivo study of antioxidants.

Anti-infective potential of natural products: how to develop a stronger in vitro 'proof-of-concept'.

Natural products, either as pure compounds or as standardized plant extracts, provide unlimited opportunities for new drug leads because of the unmatched availability of chemical diversity. To secure this, a number of pivotal quality standards need to be set at the level of extract processing and primary evaluation in pharmacological screening models. This review provides a number of recommendations that will help to define a more sound 'proof-of-concept' for antibacterial, antifungal, antiviral and antiparasitic potential in natural products. An integrated panel of pathogens is proposed for antimicrobial profiling, using accessible standard in vitro experimental procedures, endpoint parameters and efficacy criteria. Primary requirements include: (1) use of reference strains or fully characterized clinical isolates, (2) in vitro models on the whole organism and if possible cell-based, (3) evaluation of selectivity by parallel cytotoxicity testing and/or integrated profiling against unrelated micro-organisms, (4) adequately broad dose range, enabling dose-response curves, (5) stringent endpoint criteria with IC(50)-values generally below 100microug/ml for extracts and below 25microM for pure compounds, (6) proper preparation, storage and in-test processing of extracts, (7) inclusion of appropriate controls in each in vitro test replicate (blanks, infected and reference controls) and (8) follow-up of in vitro activity ('hit'-status) in matching animal models ('lead'-status).

Antiamoebic activity of iridoids from Morinda morindoides leaves.

An aqueous decoction (dried extract), an 80 % methanolic extract from Morinda morindoides (Rubiaceae) leaves, and five iridoids isolated from the 80 % methanolic extract were evaluated in vitro for their activity against Entamoeba histolytica and their cytotoxicity. The aqueous decoction and the 80 % methanolic extract exhibited a promising antiamoebic activity with IC (50) values of 3.1 +/- 1.7 and 1.7 +/- 0.6 microg/mL, respectively. All tested iridoids displayed antiamoebic activity, the most active being epoxygaertneroside (IC (50): 1.3 +/- 0.4 microg/mL) and methoxygaertneroside (IC (50): 2.3 +/- 0.7 microg/mL) followed by gaertneroside, acetylgaertneroside and gaertneric acid with IC (50) values of 4.3 +/- 1.8, 5.4 +/- 1.4 and 7.1 +/- 1.4 microg/mL, respectively. Synergistic effects between the iridoids tested, or with other constituents, may explain the high activity of the extracts. All extracts and iridoids were devoid of any cytotoxic effect against MT-4 cells at the highest test concentration of 250 microg/mL. These findings support at least in part the traditional use of Morinda morindoides leaves for the treatment of amoebiasis in the Democratic Republic of Congo.

Phytochemical investigation and antioxidant activity of Duranta repens.

The ethylacetate fraction of the methanol extract of Duranta repens L. (Verbenaceae) showed radicalscavenging activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Three compounds were isolated from this fraction, i.e. the phenylethanoid glycoside acteoside, the iridoid lamiide and the saponin pseudo-ginsenoside-RT1. Acteoside showed an IC50 of 3.05 +/- 0.09 microg/mL in the DPPH assay, while lamiide and pseudo-ginsenoside-RT1 were not active.

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.

Bioguided isolation of pharmacologically active plant components, still a valuable strategy for the finding of new lead compounds?

The position of natural products research in the drug discovery and development process nowadays is discussed. A flow chart for the study of plants used in traditional medicine, and the composition of a multidisciplinary research team for the investigation of medicinal plants are presented, and some recommendations are made for the future of bioassay-guided isolations and the use of standardised plant extracts in developing countries.

Method development and validation for monitoring in vivo oxidative stress: evaluation of lipid peroxidation and fat-soluble vitamin status by HPLC in rat plasma.

Monitoring in vivo oxidative stress implicates the evaluation of damage and defence parameters by well-established, validated methods. We report two optimized and validated HPLC methods for measurement of malondialdehyde (MDA) and fat-soluble vitamins in rat plasma. For the MDA method, optimization experiments of the thiobarbituric acid test resulted in the addition of 1% butylhydroxytoluene to the reaction mixture and in a heating time reduction to 40 min, ensuring inhibition of further lipid peroxidation during the test. Validation experiments showed good linearity, precision and recovery. The use of HPLC with coulometric array detection technology permits simultaneous and sensitive analysis of different fat-soluble vitamins and related compounds (tocopherols, retinoids, carotenoids and coenzyme Q10), which are identified by both retention time and electrochemical characteristics. Furthermore, this method is extended to the analysis of coenzyme Q9, the predominant homologue in rats. Validation experiments with rat plasma gave good results.