K. Foubert

Antiplasmodial and other constituents from four Indonesian Garcinia spp.

Phytochemical investigations of four Garcinia spp. from Indonesia, i.e. Garcinia griffithii T. Anderson, Garcinia celebica L., Garcinia cornea L. and Garcinia cymosa K. Schum (Clusiaceae), have resulted in the isolation of a xanthone, 1,5-dihydroxy-3,6-dimethoxy-2,7-diprenylxanthone, 1,7-dihydroxyxanthone, isoxanthochymol, beta-sitosterol-3-O-beta-D-glucoside and stigmasterol-3-O-beta-D-glucoside from the stem bark of G. griffithii; friedelin and 3beta-hydroxy-23-oxo-9,16-lanostadien-26-oic acid or garcihombronane D from leaves of G. celebica; 23-hydroxy-3-oxo-cycloart-24-en-26-oic acid and epicatechin from stem bark of G. cornea; (+/-)-morelloflavone, morelloflavone-7-O-beta-D-glucoside or fukugiside, the triterpene 3beta-hydroxy-5-glutinen-28-oic acid and canophyllol from stem bark of G. cymosa. The xanthone and garcihombronane D displayed a selective activity against Plasmodium falciparum; isoxanthochymol and the triterpene beta-hydroxy-5-glutinen-28-oic acid a broad but non-selective antiprotozoal activity.

Rapid quantification of 14 saponins of Maesa lanceolata by UPLC–MS/MS

Saponins are high molecular weight glycosides which are known for their broad range of biological activities. In case of Maesa lanceolata, a tree growing in African countries, the maesasaponins showed virucidal, haemolytic, molluscicidal and anti-angiogenic activity. Since the different activities are dependent on the structure of the saponins, a method was developed and validated for the analysis of the individual saponins in this plant. Since the saponins were only present in small amounts, it was necessary to develop a very sensitive analytical method. For the fast and sensitive analysis of the extracted and purified plant samples ultra-performance liquid chromatography was coupled to a triple quadrupole mass spectrometer for MS/MS detection. A method in positive ESI mode, using sodium acetate in the mobile phase, was developed. The sodium adduct ion was selected as the precursor ion since it provided better sensitivity and a better, more stable fragmentation compared to the deprotonated and protonated ions. The intensity of the signal obtained by fragmentation of the sodium adducts of the saponins, was optimized by the addition of different concentrations of sodium acetate to the mobile phase. Reference standards were not available for all 14 saponins. Therefore, a relative MS/UV response was calculated allowing the estimation of the saponins in real samples. alpha-Hederin was used as external standard. The method was linear over the investigated concentration range with a good correlation coefficient (>0.99). The intra- and inter-day precisions were below 15% for most maesasaponins with the exception of maesasaponin II, which showed a precision within 20%. The recoveries of the spiked pure compounds maesasaponin IV.1 and VII.1 were 96.6% and 85.5%, respectively. The validated method can be applied in the investigation of the content of 14 saponins in transgenic and non-transgenic plant material of M. lanceolata.

New furanoditerpenoids from Croton jatrophoides.

Four furanoditerpenoids were isolated from roots of Croton jatrophoides (Euphorbiaceae) collected in Tanzania. In addition to the known compounds penduliflaworosin and teucvin (mallotucin A), a new teucvin isomer, which was named isoteucvin, and a furanoditerpenoid with a new skeleton, for which the name jatrophoidin was adopted, were isolated. Their structures were elucidated by spectroscopic methods such as ESI-MS and NMR, including (1)H-, (13)C-, and two-dimensional NMR. The crystal structures of isoteucvin and jatrophoidin were solved using single-crystal X-ray diffraction, by which we also established the absolute configuration of jatrophoidin. The refined crystal structure of isoteucvin has the same (absolute) configuration as jatrophoidin, although the X-ray diffraction data of isoteucvin were not conclusive with respect to the absolute configuration.

In vitro antiprotozoal activity and cytotoxicity of extracts and isolated constituents from Greenwayodendron suaveolens

ETHNOPHARMACOLOGICAL RELEVANCE The Nkundo people (Nkundo area of Bolongo, Mai-Ndombe district, Bandundu Province, DR Congo) use various plant parts of the tree Greenwayodendron suaveolens (Engl. & Diels) Verdc. (syn. Polyalthia suaveolens Engl. & Diels) (Annonaceae) against malaria, but its antiprotozoal constituents are not known. MATERIALS AND METHODS The crude 80% ethanol extract from the fruits, leaves, root bark and stem bark and 16 fractions were assessed in vitro for their antiprotozoal activity against Trypanosoma brucei brucei, T. cruzi, Leishmania infantum and the chloroquine and pyrimethamine-resistant K1 strain of Plasmodium falciparum (Pf-K1). Their cytotoxic effects were evaluated against MRC-5 cells. Active constituents were isolated by chromatographic means, identified using spectroscopic methods, and evaluated in the same assays. RESULTS The root bark extract showed the highest activity against P. falciparum K1 (IC50 0.26µg/mL) along with the stem bark alkaloid fraction (IC50 0.27µg/mL). The root bark alkaloid fraction had a pronounced activity against all selected protozoa with IC50 values <1µg/mL. The 90% methanol fractions of the different plant parts showed a pronounced activity against P. falciparum K1, with IC50 values ranging between 0.36µg/mL and 0.69µg/mL. Four constituents were isolated: the triterpenes polycarpol, and dihydropolycarpol, the latter one being reported for the first time from nature, and the alkaloids polyalthenol and N-acetyl-polyveoline. They were active to a various degree against one or more protozoa, mostly accompanied by cytotoxicity. The highest selectivity was observed for N-acetyl-polyveoline against P. falciparum K1 (IC50 2.8µM, selectivity index 10.9). CONCLUSIONS These results may explain at least in part the traditional use of this plant species against parasitic diseases such as malaria in DR Congo.

Safety assessment of a traditionally used extract from leaves of Boldoa purpurascens

ETHNOPHARMACOLOGICAL RELEVANCE Boldoa purpurascens Cav. (Nyctaginaceae) is a plant species used in traditional medicine in Cuba as a diuretic. AIM OF THE STUDY The aim of the present investigation was to evaluate the safety profile of a hydroalcoholic extract from leaves of Boldoa purpurascens. MATERIALS AND METHODS First, an experimental study to assess the oral acute toxicity at a dose of 2000mg/kg body weight of the extract was carried out. Potential genotoxicity of the extract was evaluated using the Ames test and the micronucleus induction assay in mouse bone marrow. In the Ames test a concentration range of 50, 100, 150, 300 and 500µg/plate was tested. In the micronucleus induction assay, doses of 500, 1000 and 2000mg/kg of body weight were tested. For completeness, since the extract contains saponins, the evaluation of the hemolytic activity, ocular and skin irritation were included. RESULTS No signs or symptoms of toxicity were observed in the oral acute toxicity test (body weight at baseline, seven days and end of the experiment of 236.41±20.07, 256.81±30.44 and 240.02±26.16 respectively for the treated group). The hydroalcoholic extract from the leaves was not mutagenic in the Ames test, and no genotoxicity was observed in the micronucleus assay. A hemolysis test at concentration of 1mg/mL confirmed hemolytic activity, which is not a safety concern since saponins are not absorbed after oral administration. In order to evaluate the percentage of protein denaturation, the ocular irritability index was calculated. The extract was found to be irritating. Finally, skin irritability was evaluated and the irritation index was equal to zero. CONCLUSIONS Based on the toxicological evaluation of a traditionally used hydroalcoholic extract from the leaves of Boldoa purpurascens we can confirm the safety of its oral use.

Flavonoids from Boldoa purpurascens inhibit proinflammatory cytokines (TNF-α and IL-6) and the expression of COX-2: Flavonoids from Boldoa purpurascens

The flavonoids comprise a large class of plant metabolites distributed in food plants. These compounds have antioxidant, antitumor, antiallergic, and anti‐inflammatory effects. The molecular mechanisms of their biological activities remain to be clearly understood. We investigated the in vitro anti‐inflammatory potential of a flavonoid mixture and isolated compounds from the leaves of Boldoa purpurascens. Our results provide direct evidence of the anti‐inflammatory effects of the mixture, which are mediated by the inhibition of the proinflammatory cytokines tumor necrosis factor α and interleukin 6 as well as the modulation of the expression of cyclooxygenase 2.