Evaluation of the flora of Puerto Rico for in vitro antiplasmodial and antimycobacterial activities.

The emergence of resistant strains of Plasmodium falciparum and Mycobacterium tuberculosis underscores the need for novel drugs that are effective against these microorganisms. As part of our screening programme of the flora of Puerto Rico, we tested a number of ethanol extracts of higher plants for antiplasmodial and antimycobacterial activities. A total of 40 extracts belonging to 23 plant families and 37 species were tested for antiplasmodial activity. Five extracts demonstrated activity against Plasmodium falciparum in vitro (50%-100% parasite suppression at 5 microg/mL). Another 63 extracts belonging to 30 plant families and 50 species were tested in vitro against Mycobacterium tuberculosis. Two extracts were found to be active, Ficus citrifolia and Pisonia borinquena (85% or more inhibition of microbial growth at 100 microg/mL of extract).     

In vitro antiplasmodial activity of some plants used in Kisii,Kenya against malaria and their chloroquine potentiation effects

Fifty-five organic and aqueous extracts of 11 plants used in malaria therapy in Kisii District, Kenya were tested in vitro against chloroquine (CQ)-sensitive and resistant strains of Plasmodium falciparum. Of the plants tested, 73% were active (IC(50) < 100 microg/ml). Three plants, Vernonia lasiopus, Rhamnus prinoides and Ficus sur afforded extracts with IC(50) values ranging less than 30 microg/ml against both CQ-sensitive and resistant strains. Combination of some extracts with CQ against the multi-drug resistant P. falciparum isolate V1/S revealed some synergistic effect. The plant extracts with low IC(50) values may be used as sources for novel antimalarial compounds to be used alone or in combination with CQ.     

Antimalarial effects of eight African medicinal plants

Crude hot water extracts from eight medicinal plants collected in Togo, West Africa, were examined for antimalarial properties against Plasmodium falciparum using an in vitro test. The activity differed with the plant species with extracts of Cassia siamea, Jatropha gossypiifolia and Pavetta crassipes capable of 100% inhibition.     

Antimalarial activity of some plants traditionally used in treatment of malaria in Kwale district of Kenya

Methanolic and water extracts of five medicinal plant species used for treatment of malaria in traditional/cultural health systems of Kwale people in Kenya were tested for antimalarial activity against Plasmodium falciparum and Plasmodium berghei, respectively and for their cytotoxic effects. The most active extracts (IC(50)<10 microg/ml) screened against chloroquine (CQ) sensitive (D6) and resistant (W2) P. falciparum clones, were the water and methanol extracts of Maytenus undata (Thunb.) Blakelock (Celasteraceae), methanol extracts of Flueggea virosa (Willd.) Voigt (Euphorbiaceae), Maytenus putterlickioides (Loes.) Excell and Mendoca (Celastraceae), and Warburgia stuhlmannii Engl. (Canellaceae). These extracts showed various cytotoxic levels on Vero E6 cells with the water extract of M. undata exhibiting least cytotoxicity. At least one of the extracts of the plant species exhibited a high chemo suppression of parasitaemia >70% in a murine model of P. berghei infected mice. These results indicate that there is potential for isolation of a lead compound from the extracts of the five plants. W. stuhlmannii and M. putterlickioides have not been reported before for antiplasmodial activity.     

In vitro antiplasmodial activity of Brazilian Cerrado plants used as traditional remedies

Twenty-seven species of native Brazilian Cerrado plants commonly used by traditional healers to treat malaria and other diseases were collected and 204 hexanic and ethanolic extracts were obtained by maceration. The antiplasmodial activity of the extracts was tested in vitro against a chloroquine resistant strain (FcB1) of Plasmodium falciparum, and cytotoxicity against the cell lines L-6 of rats and MRC-5 of human was evaluated. Thirty-two extracts showed significant inhibition rates of Plasmodium falciparum growth and of these six showed cytotoxicity against the cell lines. The strongest antiplasmodial activity was found for the hexanic extracts of Xylopia aromatica root wood (IC(50)=4.7 microg/ml), Xylopia emarginata root bark (IC(50)=4.9 microg/ml), Casearia sylvestris var. lingua leaves, stem wood and stem bark, and root wood and root bark (IC(50) values from 0.9 to 2.3 microg/ml), and Cupania vernalis leaves (IC(50)=0.9 microg/ml); and for the ethanolic extract of Aspidosperma macrocarpon root bark (IC(50)=4.9 microg/ml). However, the best selectivity towards Plasmodium falciparum was observed for the hexanic root bark extract of Matayba guianensis (IC(50) on Plasmodium falciparum=6.1 microg/ml, SI=16.4 for MRC-5) and the ethanolic root bark extract of Aspidosperma macrocarpon (IC(50) on Plasmodium falciparum=4.9 micro/ml, SI=16.2 for MRC-5).     

Anti-plasmodial activity and toxicity of extracts of plants used in traditional malaria therapy in Meru and Kilifi Districts of Kenya

The methanol and aqueous extracts of 10 plant species (Acacia nilotica, Azadirachta indica, Carissa edulis, Fagaropsis angolensis, Harrissonia abyssinica, Myrica salicifolia, Neoboutonia macrocalyx, Strychnos heningsii, Withania somnifera and Zanthoxylum usambarensis) used to treat malaria in Meru and Kilifi Districts, Kenya, were tested for brine shrimp lethality and in vitro anti-plasmodial activity against chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum (NF54 and ENT30). Of the plants tested, 40% of the methanol extracts were toxic to the brine shrimp (LD(50)<100micro/ml), while 50% showed in vitro anti-plasmodial activity (IC(50)<100microg/ml). The methanol extract of the stem bark of N. macrocalyx had the highest toxicity to brine shrimp nauplii (LD(50) 21.04+/-1.8microg/ml). Methanol extracts of the rest of the plants exhibited mild or no brine shrimp toxicity (LD(50)>50microg/ml). The aqueous extracts of N. macrocalyx had mild brine shrimp toxicity (LD(50) 41.69+/-0.9microg/ml), while the rest were lower (LD(50)>100microg/ml). The methanol extracts of F. angolensis and Zanthoxylum usambarense had IC(50) values <6microg/ml while the aqueous ones had values between 6 and 15microg/ml, against both chloroquine-sensitive and resistant P. falciparum strains. The results support the use of traditional herbs for anti-malarial therapy and demonstrate their potential as sources of drugs.     

Antiplasmodial activity of extracts and quassinoids isolated from seedlings of Ailanthus altissima (Simaroubaceae)

Extracts and isolated compounds from seedlings of Ailanthus altissima, were assessed for antiplasmodial activity in vitro. Two quassinoids, ailanthone and 6alpha-tigloyloxychaparrinone, isolated from the active extracts showed activity against both chloroquine-resistant and chloroquine-sensitive strains of Plasmodium falciparum in vitro. Only ailanthone demonstrated low toxicity against the Vero cell line (kidney cells from the African green monkey). This is the first report of the isolation and antiplasmodial activity of 6alpha-tigloyloxychaparrinone from this species.     

In vitro screening of some Strychnos species for antiplasmodial activity

The antiplasmodial activity of crude extracts of 19 species of Strychnos (Loganiaceae) was assessed in vitro against a chloroquine-susceptible strain of Plasmodium falciparum. For each species, ethyl acetate (EtOAc) extracts were analysed and, for the most active species, methanolic (MeOH) extracts were also tested. Among them, Strychnos variabilis De Wild. seemed to be very promising (inhibitory concentration 50% (IC50) < 5 microg/ml) whereas two other species, Strychnos gossweileri Exell and Strychnos mellodora S. Moore, could be interesting (IC50 < 15 microg/ml) in further antimalarial studies.     

A search for natural bioactive compounds in Bolivia through a multidisciplinary approach. Part V. Evaluation of the antimalarial activity of plants used by the Tacana Indians

One hundred and twenty-five extracts of 122 different plant species traditionally used by the Tacana, a native community living in lowland forest at the base of the last foothills of the Cordillera Oriental of the Bolivian Andes, were screened for antimalarial activity in vitro on Plasmodium falciparum chloroquine resistant (D2) and sensitive strains (F32), and were evaluated in vivo on rodent malaria Plasmodium berghei. Five ethanolic stembark extracts showed marked activity either in vitro or in vivo, and only one of them, Bowdichia virgilioides being traditionally used against malaria, was active in vitro (IC50=1 microg/ml on both strains) and in vivo (51% at 100 mg/kg). Other active extracts were from Caesalpinia pluviosa bark displaying activity in vitro against chloroquine resistant strain (IC50 8.3 microg/ml), traditionally used against dysentery; two Lauraceae bark extracts, Nectandra aff. hihua and Licaria canella respectively used for construction purposes and against stomach ache, both displaying activity in vitro against P. falciparum sensible and resistant strains (IC50 around 4 microg/ml); finally, the bark of a strongly aromatic Burseraceae, Protium glabrescens exuding an anti-inflammatory and analgesic resin, was active in vivo only (61% at 100 mg/kg). Results are discussed in relation with Tacana traditional medicine.     

Antimalarial activity of Ajuga remota Benth (Labiatae) and Caesalpinia volkensii Harms (Caesalpiniaceae): in vitro confirmation of ethnopharmacological use

Field trips to herbalists' practices in an area about 200 miles around Nairobi (Kenya) enabled us to make a list of medicinal plant species preferentially used to treat malaria. Ajuga remota and Caesalpinia volkensii were further investigated as being the most frequently used species. Aqueous decoctions, ethanol macerates, and petroleum ether, methanol and water Soxhlet extracts of these plants were further tested for their in vitro antimalarial properties in a chloroquine sensitive (FCA/20GHA) and resistant (W2) strain of Plasmodium falciparum. The activity was assessed by the parasite lactate dehydrogenase (pLDH) assay method. There was a concentration-dependent inhibition by the vegetal extracts of both plants. The IC(50) of the most active A. remota extract (ethanol macerate) was 55 and 57 microg/ml against FCA/20GHA and W2, respectively. For C. volkensii, it was the Soxhlet-water extract which was most active against FCA/20GHA with an IC(50) of 404 microg/ml while the petroleum ether extract exhibited the most activity against W2 with an IC(50) of 250 microg/ml. Further phytochemical work is being done in order to identify the active principles.     

Biological screening of Italian medicinal plants for antibacterial activity

Some 68 plant extracts from 65 species belonging to 25 families were investigated for antibacterial activity against eight gram-positive and gram-negative bacteria. Of the 68 extracts, 64 (94.1%) exhibited inhibitory effects against one or more microorganisms. Furthermore, among the active extracts, 12 from 11 species exhibited a broad spectrum of activity. Discussion on the probable chemical components responsible for this activity is included.     

Antimicrobial activity of 20 plants used in folkloric medicine in the Palestinian area

Ethanolic and aqueous extracts of 20 Palestinian plant species used in folk medicine were investigated for their antimicrobial activities against five bacterial species (Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa) and one yeast (Candida albicans). The plants showed 90% of antimicrobial activity, with significant difference in activity between the different plants. The most antimicrobially active plants were Phagnalon rupestre and Micromeria nervosa, whereas, the least active plant was Ziziphus spina-christi. Only ten of the tested plant extracts were active against C. albicans, with the most active from M. nervosa and Inula viscosa and the least active from Ruscus aculeatus. Of all extracts the ethanolic extract of M. nervosa was the most active, whereas, the aqueous extract of Phagnalon rupestre was the most active of all aqueous extracts tested. The ethanolic extracts (70%) showed activity against both Gram positive and negative bacteria and 40% of these extracts showed anticandidal activity, whereas, 50% of the aqueous extracts showed antibacterial activity and 20% of these extracts showed anticandidal activity.     

Antiparasitic activities of medicinal plants used in Ivory Coast

During an ethnopharmacological survey of antiparasitic medicinal plants used in Ivory Coast, 17 plants were identified and collected. Polar, non-polar and alkaloidic extracts of various parts of these species were evaluated in vitro in an antiparasitic drug screening. Antimalarial, leishmanicidal, trypanocidal, antihelminthiasis and antiscabies activities were determined. Among the selected plants, Anogeissus leiocarpus and Terminalia glaucescens were strongly active against Plasmodium falciparum. Lawsonia inermis, selectively prescribed against trypanosomiasis shows interesting trypanocidal activities as did other 15 plants. Anthelmintic activities were found for 10 active species and 2 species (Uvaria afzelli and Monodora myristica) were actives against mites.     

Antiprotozoal and cytotoxic activities in vitro of Colombian Annonaceae

Ethnobotanical and chemotaxonomical studies for antiparasitic activity of Colombian Annonaceae were carried out. In vitro antiprotozoal activity of 36 extracts obtained from six different species was determined against promastigotes of three Leishmania species, epimastigotes of Trypanosoma cruzi and both chloroquine sensitive (F32) and resistant (W2) Plasmodium falciparum. Cytotoxic activity was evaluated in U-937 cells. Active extracts were selected according their selectivity index (SI). Extracts from Annona muricata, Rollinia exsucca, Rollinia pittieri and Xylopia aromatica were active against Leishmania spp. and Trypanosoma cruzi showing IC50 values lower than 25 microg/ml. Hexane extract from Rollinia pittieri leaves was the most selective against Trypanosoma cruzi and Leishmania spp. (IS=10 and 16, respectively). The extracts from Desmopsis panamensis, Pseudomalmea boyacana, Rollinia exsucca and Rollinia pittieri showed good antiplasmodial activity (IC50 < 10 microg/ml). No correlation between antiplasmodial activity and inhibition of beta-hematin production was found. The present study gives specific and useful information about antiprotozoal and cytotoxic activities of some Annonaceae extracts. Results presented here also demonstrate which plants and/or plant parts could be useful in the treatment of leishmaniasis, Chagas' disease and malaria.     

Antiplasmodial and antiamoebic activities of medicinal plants from Sierra Leone

Crude ethanol extracts of 18 medicinal plants from Sierra Leone, West Africa were examined for antiplasmodial activity against Plasmodium falciparum, using an in vitro microtest. Eleven of these extracts were also screened for in vitro antiamoebic activity against Entamoeba histolytica. Only one plant extract, Triclisia patens (Menispermaceae) showed significant antiplasmodial activity (IC(50) = 8 microg/mL). None of the plant extracts was effective against Entamoeba histolytica.     

Evaluation of plants used for antimalarial treatment by the Maasai of Kenya

Semi-structured interviews with three Maasai herbalists led to the identification and collection of 21 species of plants used to treat malaria. Extracts were evaluated using in vitro antimalarial and cytotoxicity assays. Of the species tested, over half were antiplasmodial (IC50<10 microg/ml), and all but one (Gutenbergia cordifolia Benth.) displayed selectivity for the malaria parasite Plasmodium falciparum as indicated by a lack of cytotoxicity (ED50>20 microg/ml) against cultured KB cells. The results of this preliminary investigation support the traditional knowledge of Maasai herbalists and justify ethnomedical inquiry as a promising method, specifically, in antimalarial therapy, to yield leads for drug discovery.     

Screening of Thai medicinal plant extracts and their active constituents for in vitro antimalarial activity

To discover antimalarial substances from plants cultivated in Thailand 80%-EtOH extracts from selected plants were screened for in vitro antimalarial activity against the drug resistant K1 strain of Plasmodium falciparum. In total, 86 Thai medicinal plant samples representing 48 species from 35 genera in 16 families were screened and two species (Polyalthia viridis and Goniothalamus marcanii) were found to show notable antimalarial activity (IC50: 10.0 and 6.3 microg/mL). Marcanine A and 16-hydroxycleroda-3,13(14)Z-dien-15,16-olide were identified as the respective major active constituents in P. viridis and G. marcanii, respectively.     

Anti-plasmodial activity of some Kenyan medicinal plant extracts singly and in combination with chloroquine

Sixty organic and aqueous extracts of eleven plants used for the control of malaria by local communities in Kisii District, Kenya were screened for in vitro anti-plasmodial activity. The plants selection was based on existing ethnobotanical information and interviews with local communities. The extracts were tested against chloroquine sensitive and resistant laboratory adapted strains of Plasmodium falciparum. The study revealed that 63.6% of the plants were active (IC50 < or = 100 microg/mL). Extracts of four plants, Ekebergia capensis, Stephania abyssinica, Ajuga remota and Clerodendrum myricoides gave IC50 values below 30 microg/mL against both chloroquine sensitive and resistant P. falciparum strains. Combination of extracts of E. capensis and C. myricoides with chloroquine against the multi-drug resistant P. falciparum isolate (V1/S) revealed synergistic effect. The plants which showed activity may be useful as sources for novel anti-plasmodial compounds.     

Screening of selected indigenous plants of Cambodia for antiplasmodial activity

The in vitro antiplasmodial activity of 117 aqueous, methanol and dichloromethane extracts derived from different parts of 28 indigenous wild plant species was studied. These plants are commonly used in Cambodian traditional medicine. The plant extracts were tested for in vitro activity against a chloroquine resistant Plasmodium falciparum strain (W2). Nine extracts were moderately active with IC(50) values ranging between 5 and 10 microg/ml, 17 extracts were active with IC(50) values ranging between 1 and 5 microg/ml. These 26 extracts derived from eight plants belong to six families. The most active extracts were dichloromethane and came from Stephania rotunda and Brucea javanica with IC(50) values of 1 microg/ml and a selectivity index > or = 25. It is interesting to note that some aqueous extracts were as active as dichloromethane extracts especially aqueous extracts of Stephania rotunda, Brucea javanica, Phyllanthus urinaria and Eurycoma longifolia with IC(50) values of < or = 4 microg/ml. These results are in agreement with statements of healers on traditional uses of these plants for the treatment of malaria and/or fever. In this study, we report the antiplasmodial potential activity of eight plant species from Cambodia. Among them four are tested for the first time.     

Evaluation of antiprotozoal and plasmodial enoyl-ACP reductase inhibition potential of turkish medicinal plants

A total of 58 extracts of different polarity were prepared from various organs of 16 species of Turkish plants and screened for their antitrypanosomal, antileishmanial and antiplasmodial activities. No significant activity was observed against Trypanosoma cruzi, whereas many extracts showed appreciable trypanocidal potential against T. brucei rhodesiense, with the CHCl(3)-soluble portion of Phlomis kurdica being the most active (IC(50) 2.7 microg[sol ]mL). Almost all extracts, particularly the CHCl(3) phases, exhibited growth inhibition activity against Leishmania donovani amastigotes. The CHCl(3)-solubles of Putoria calabrica roots (IC(50) 1.9 microg[sol ]mL), Wendlandia ligustroides leaves (IC(50) 2.1 microg[sol ]mL) and Rhododendron luteum leaves (IC(50) 2.3 microg[sol ]mL) displayed the highest leishmanicidal potential. The majority of the extracts also possessed antiplasmodial activity against the multi-drug resistant K1 Plasmodium falciparum strain. The most potent antiplasmodial activity was observed with the CHCl(3) extracts of Phlomis kurdica (IC(50) 1.5 microg[sol ]mL), P. leucophracta (IC(50) 1.6 microg[sol ]mL), Scrophularia cryptophila (IC(50) 1.8 microg[sol ]mL), Morina persica (IC(50) 1.9 microg[sol ]mL) and the aqueous root extract of Asperula nitida subsp. subcapitellata (IC(50) 1.6 microg[sol ]mL). Twenty-one extracts with significant antimalarial activity (IC(50) < 5 microg[sol ]mL) were also tested for their ability to inhibit the purified enoyl-ACP reductase (FabI), a crucial enzyme in the fatty acid biosynthesis of P. falciparum. The CHCl(3) extract of Rhododendron ungernii leaves (IC(50) 10 microg[sol ]mL) and the H(2)O-soluble portion of Rhododendron smirnovii leaves (IC(50) 0.4 microg[sol ]mL) strongly inhibited the FabI enzyme. The preliminary data indicate that some (poly)phenolic compounds are responsible for the FabI inhibition potential of these extracts. The presented work reports for the first time the antiprotozoal activity of nine different genera as well as a target specific antimalarial screening for the identification of P. falciparum FabI inhibitors from medicinal plant extracts.