Antiparasitic activities of two sesquiterpenic lactones isolated from Acanthospermum hispidum D.C.

Aerial parts of Acanthospermum hispidum D.C. are often used by traditional healers in Benin for various diseases and especially for malaria. To identify active compounds from extracts of Acanthospermum hispidum D.CV. leaves previously shown to possess antimalarial properties and analyse in vivo activity and toxicity of crude extracts. Compounds were isolated from aerial part of Acanthospermum hispidum D.C. and structurally elucidated using extensive spectroscopic analysis. Antiplasmodial activity was evaluated in vitro against a chloroquine-sensitive strain of Plasmodium falciparum (3D7) using the measurement of the plasmodial lactate dehydrogenase activity and in vivo against Plasmodium berghei berghei by the 4-day suppressive test. Selectivity of extract and purified compounds on Plasmodium parasites were evaluated by using MTT test on J774 macrophage like murine cells and WI38 human normal fibroblasts and also against two other parasites: Trypanosoma brucei brucei and Leishmania mexicana mexicana. Acute and sub-acute toxicities of a crude extract were evaluated on mice. Two known sesquiterpenic lactones were isolated: 1 (15-acetoxy-8β-[(2-methylbutyryloxy)]-14-oxo-4,5-cis-acanthospermolide) and 2 (9α-acetoxy-15-hydroxy-8β-(2-methylbutyryloxy)-14-oxo-4,5-trans-acanthospermolide). 1 and 2 showed in vitro antiplasmodial activity against the chloroquine-sensitive strain (3D7) with IC(50) of 2.9±0.5 and 2.23±0.09μM respectively. Only 2 showed a high selectivity index (SI: 18.4) on Plasmodium compared to cytotoxicity against human fibroblasts cell line (WI38). 1 and 2 also showed interesting antiparasitic activities in vitro against Trypanosoma brucei brucei (IC(50) of 2.45±0.49 and 6.36±1.42μM respectively) and Leishmania mexicana mexicana (IC(50) of 0.94±0.05 and 2.54±0.19μM respectively). Furthermore, crude acidic water extract and fractions containing one of the two isolated compounds displayed a weak in vivo antimalarial activity against Plasmodium berghei berghei with a long half-life causing a delayed effect. In vivo acute (2000mg/kg) and sub-acute (1000mg/kg) toxicity tests on the crude acidic water extract did not show toxicity. Crude acidic water extract, fractions and pure isolated compounds from Acanthospermum hispidum showed promising in vitro antiplasmodial activity. Despite our study did not show in vivo acute and subacute toxicities of the crude acidic water extract, its weak in vivo antimalarial activity and the in vitro cytotoxicity of pure compounds and enriched extracts containing 1 and 2 indicate that the aerial parts of Acanthospermum hispidum should be used with caution for malaria treatments.

Ganfon H ，Bero J ，Tchinda AT ，Gbaguidi F ，Gbenou J ，Moudachirou M ，Frédérich M ，Quetin-Leclercq J ... -  《-》

In vitro antiplasmodial activity of plants used in Benin in traditional medicine to treat malaria.

Bero J ，Ganfon H ，Jonville MC ，Frédérich M ，Gbaguidi F ，DeMol P ，Moudachirou M ，Quetin-Leclercq J ... -  《-》

In vivo antimalarial activity of Keetia leucantha twigs extracts and in vitro antiplasmodial effect of their constituents.

The West African tree Keetia leucantha (Rubiaceae) is used in traditional medicine in Benin to treat malaria. The twigs dichloromethane extract was previously shown to inhibit in vitro Plasmodium falciparum growth with no cytotoxicity (>100µg/ml on human normal fibroblasts). The dichloromethane and aqueous extracts of twigs of K. leucantha were evaluated in vivo against Plasmodium berghei NK 173 by the 4-day suppressive test and in vitro against a chloroquine-sensitive strain of Plasmodium falciparum (3D7) using the measurement of the plasmodial lactate dehydrogenase activity. Bioguided fractionations were realized and compounds were structurally elucidated using extensive spectroscopic analysis. The in vivo antimalarial activity of K. leucantha dichloromethane and aqueous twigs extracts were assessed in mice at the dose of 200mg/kg/day. Both extracts exhibited significant effect in inhibiting parasite growth by 56.8% and 53.0% (p<0.0001) on day 7-postinfection. An LC-MS analysis and bioguided fractionations on the twigs dichloromethane extract led to the isolation and structural determination of scopoletin (1), stigmasterol (2), three phenolic compounds: vanillin (3), hydroxybenzaldehyde (4) and ferulaldehyde (5), eight triterpenic esters (6-13), oleanolic acid and ursolic acid. The antiplasmodial activity of the mixture of the eight triterpenic esters showed an antiplasmodial activity of 1.66 ± 0.54 µg/ml on the 3D7 strain, and the same range of activity was observed for isolated isomers mixtures. This is the first report on the in vivo activity of K. leucantha extracts, the isolation of thirteen compounds and analysis of their antiplasmodial activity. The results obtained may partially justify the traditional use of K. leucantha to treat malaria in Benin.

Bero J ，Hérent MF ，Schmeda-Hirschmann G ，Frédérich M ，Quetin-Leclercq J ... -  《-》

In vitro antitrypanosomal and antileishmanial activity of plants used in Benin in traditional medicine and bio-guided fractionation of the most active extract.

The aim of the study was to evaluate the in vitro antitrypanosomal and antileishmanial activity of crude extracts of 10 plant species traditionally used in Benin to treat parasitic infections. For each species, dichloromethane, methanol and aqueous extracts were tested. Their antitrypanosomal and antileishmanial activities were evaluated in vitro on Trypanosoma brucei brucei (strain 427) (Tbb) and on promastigotes of Leishmania mexicana mexicana (MHOM/BZ/84/BEL46) (Lmm). The best growth inhibition was observed with the dichloromethane extracts of aerial parts of Acanthospermum hispidum DC. (Asteraceae) (IC(50)=14.5 μg/ml on Tbb and 11.1 μg/ml on Lmm), twigs of Keetia leucantha (K. Krause) Bridson (syn. Plectronia leucantha Krause) (IC(50)=5.8 μg/ml on Tbb), aerial parts of Byrsocarpus coccineus Schumach. & Thonn (syn. Rourea coccinea (Schumach. & Thonn.) Hook.f.) (IC(50)=14.7 μg/ml on Tbb) and aerial parts of Carpolobia lutea G.Don. (IC(50)=18.3 μg/ml on Tbb). All these extracts had a low cytotoxicity. It is not the case for the methanolic and water extracts of roots of Anchomanes difformis (Blume) Engl. (IC(50)=14.7 and 13.8 μg/ml on Tbb) which were toxic at the same concentration range on WI38, human cells. A bio-guided fractionation of the most active extract of Keetia leucantha allowed to identify oleanolic acid and ursolic acid as responsible for the observed activities. Our study gives some justification for antiparasitic activity of some investigated plants.

Bero J ，Hannaert V ，Chataigné G ，Hérent MF ，Quetin-Leclercq J ... -  《-》

In vitro and in vivo antimalarial and cytotoxic activity of five plants used in congolese traditional medicine.

The in vitro antiplasmodial activity and cytotoxicity of methanolic and dichloromethane extracts from five Congolese plants were evaluated. The plants were selected following an ethnobotanical survey conducted in D.R. Congo and focusing on plants used traditionally to treat malaria. The in vivo antimalarial activity of aqueous and methanolic extracts active in vitro was also determined in mice infected by Plasmodium berghei berghei. The growth inhibition of Plasmodium falciparum strains was evaluated using the measurement of lactate dehydrogenase activity. The extracts (aqueous, CH(3)OH, EtOH and CH(2)Cl(2)) were prepared by maceration and tested in vitro against the 3D7 (chloroquine sensitive) and W2 (chloroquine resistant) strains of Plasmodium falciparum and against the human normal fetal lung fibroblasts WI-38 to determine the selectivity index. Some extracts were also used at the dose of 300 mg/kg to evaluate their activity in mice infected since 4 days by Plasmodium berghei. Two plants presented a very high activity (IC(50)<3 microg/ml). These plants were Strychnos icaja roots bark (MeOH and CH(2)Cl(2)) and Physalis angulata leaves (MeOH and CH(2)Cl(2)). One plant (Anisopappus chinensis whole plant, MeOH and CH(2)Cl(2)) presented a high activity (IC50<15 microg/ml). The extracts of Anisopappus chinensis and Physalis angulata showed also a good inhibition of parasitemia in vivo. Flavonoids, phenolic acids and terpenes were identified in these plants by a general phytochemical screening method. Three plants showed a very interesting antiplasmodial activity (Anisopappus chinensis, Physalis angulata and Strychnos icaja) and one of them showed a good selectivity index (>10, Anisopappus chinensis). Anisopappus chinensis and Physalis angulata were also active in vivo.

Lusakibanza M ，Mesia G ，Tona G ，Karemere S ，Lukuka A ，Tits M ，Angenot L ，Frédérich M ... -  《-》