In vitro antiplasmodial activity and cytotoxicity of crude extracts and compounds from the stem bark of <Emphasis Type="Italic">Kigelia africana</Emphasis> (Lam.) Benth (Bignoniaceae)

In order to assess the potential of the stem bark of Kigelia africana (Lam.) Benth as source of new anti-malarial leads, n-hexane and ethyl acetate (EtOAc) extracts and four compounds isolated from the stem bark were screened in vitro against the chloroquine-resistant W-2 and two field isolates of Plasmodium falciparum using lactate dehydrogenase assay. The products were also tested for their cytotoxicity on LLC/MK2 monkey kidney cells. The EtOAc extract exhibited a significant antiplasmodial activity (IC₅₀ = 11.15 μg/mL on W-2; 3.91 and 4.74 μg/mL on field CAM10 and SHF4 isolates, respectively), whereas the n-hexane fraction showed a weak activity (IC₅₀ = 73.78 μg/mL on W-2 and 21.85 μg/mL on SHF4). Three out of the four compounds showed good activity against all the three different parasite strains (IC₅₀ < 5 μM). Specicoside exhibited the highest activity on W-2 (IC₅₀ = 1.54 μM) followed by 2β, 3β, 19α-trihydroxy-urs-12-en-28-oic acid (IC₅₀ = 1.60 μM) and atranorin (IC₅₀ = 4.41 μM), while p-hydroxycinnamic acid was the least active (IC₅₀ = 53.84 μM). The EtOAc extract and its isolated compounds (specicoside and p-hydroxycinnamic acid) were non-cytotoxic (CC₅₀ > 30 μg/mL), whereas the n-hexane extract and two of its products, atranorin and 2β, 3β, 19α-trihydroxy-urs-12-en-28-oic acid showed cytotoxicity at high concentrations, with the last one being the most toxic (CC₅₀ = 9.37 μg/mL). These findings justify the use of K. africana stem bark as antimalaria by traditional healers of Western Cameroon, and could constitute a good basis for further studies towards development of new leads or natural drugs for malaria.     

The use of microfluorometric method for activity-guided isolation of antiplasmodial compound from plant extracts

In vitro antiplasmodial activity of methanolic extracts of 16 medicinal plants was evaluated by fluorometric assay using PicoGreen. The IC50s, as determined by parasite DNA concentration, ranged from <11 to >200 and <13 to >200 μg/ml for Plasmodium falciparum 3D7 and K1, respectively; and the most active extracts were those from Anogeissus leiocarpus and Terminalia avicennoides (<11–≥14 μg/ml). Aqueous, butanolic, ethyl acetate, and methanolic fractions of these two extracts revealed butanolic fraction to have a relatively better activity (IC₅₀, 10–12 μg/ml). Activity-guided chromatographic separation of the butanolic fraction on Sephadex LH-20 followed by nuclear magnetic resonance and correlation high-performance liquid chromatography revealed the presence of known hydrolysable tannins and some related compounds—castalagin, ellagic acid, flavogallonic acid, punicalagin, terchebulin, and two other fractions. The IC₅₀s of all these compounds ranged between 8–21 μg/ml (8–40 μM) against both the strains. Toxicity assay with mouse fibroblasts showed all the extracts and isolated compounds to have IC₅₀ ≥ 1500 μg/ml, except for Momordica balsamina with <1500 μg/l. All the extracts and isolated compounds did not affect the integrity of human erythrocyte membrane at the observed IC₅₀s. However, adverse effects manifest in a concentration-dependent fashion (from IC₅₀ ≥ 500 μg/ml).     

Antiplasmodial activity of botanical extracts against Plasmodium falciparum

The absence of a vaccine and the rampant resistance to almost all antimalarial drugs have accentuated the urgent need for new antimalarial drugs and drug targets for both prophylaxis and chemotherapy. The aim of the study was to discover effective plant extracts against Plasmodium falciparum. In the present study, the hexane, chloroform, ethyl acetate, acetone, and methanol extracts of Citrus sinensis (peel), Leucas aspera, Ocimum sanctum, Phyllanthus acidus (leaf), Terminalia chebula (seed) were tested for their antimalarial activity against chloroquine (CQ)-sensitive (3D7) strain of P. falciparum which was cultured following the candle-jar method. Antimalarial evaluations of daily replacement of culture medium containing CQ and different plant crude extracts were performed on 96-well plates at 37°C for 24 and 48 h. Parasitemia was determined microscopically on thin-film Giemsa-stained preparations. Plant extracts were tested for their cytotoxicity using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay on human laryngeal cancer cell line (HEp-2) and normal cell line (Vero). Out of the 25 extracts tested, six showed good (IC₅₀ 4.76–22.76 μg/mL), 15 exhibited moderate (IC₅₀ 31.42–88.03 μg/mL), while four displayed mild (IC₅₀ > 100 μg/mL) antiplasmodial activity. The leaf ethyl acetate and methanol extracts of L. aspera; ethyl acetate, acetone, and methanol extracts of P. acidus; and seed acetone extract of T. chebula had good antiplasmodial activity (IC₅₀ = 7.81, 22.76, 9.37, 14.65, 12.68, and 4.76 μg/mL) with selectivity indices 5.43, 2.04, 4.88, 3.35, 3.42, and 9.97 for HEp-2 and >5.79, >2.20, >11.75, >3.41, >3.94, and >7.38 for Vero cells, respectively. These analyses have revealed for the first time that the components present in the solvent extracts of L. aspera, P. acidus, and T. chebula have antiplasmodial activity. The high antiplasmodial activity observed make these plants good candidates for isolation of anti-protozoal compounds which could serve as new lead structures for drug development.     

Effect of oregano (<Emphasis Type="Italic">Origanum vulgare</Emphasis> L.) and thyme (<Emphasis Type="Italic">Thymus vulgaris</Emphasis> L.) essential oils on <Emphasis Type="Italic">Trypanosoma cruzi</Emphasis> (Protozoa: Kinetoplastida) growth and ultrastructure

In the present work, we have investigated the effect of essential oils obtained from Origanum vulgare L. (oregano) and Thymus vulgaris L. (thyme) on growth and ultrastructure of diverse evolutive forms of Trypanosoma cruzi. Culture epimastigotes and bloodstream trypomastigotes were incubated for 24 h with different concentrations of oregano or thyme essential oils and with thymol (the main constituent of thyme), and the inhibitory concentration (IC)₅₀ was determined by cell counting. Crude extract of oregano essential oil inhibited epimastigote growth (IC₅₀/24 h = 175 μg/ml) and also induced trypomastigote lysis (IC₅₀/24 h = 115 μg/ml). Thyme essential oil presented IC₅₀/24 h values of 77 μg/ml for epimastigotes and 38 μg/ml for trypomastigotes, while treatment with thymol resulted in an IC₅₀/24 h of 62 μg/ml for epimastigotes and 53 μg/ml for trypomastigotes. Scanning electron microscopy of treated cells showed few morphological alterations at the plasma membrane. Observation by transmission electron microscopy showed cytoplasmic swelling with occasional morphological alterations in plasma and flagellar membrane. Our data indicate that oregano and thyme essential oils are effective against T. cruzi, with higher activity of thyme, and that thymol may be the main component responsible for the trypanocidal activity.     

Seaweeds as a source of lead compounds for the development of new antiplasmodial drugs from South East coast of India

The problems of resistant lines of Plasmodium falciparum are escalating. Twelve seaweeds species belong to five different families (Sargassaceae, Gracilariaceae, Hypneaceae, Corallinaceae and Halimedaceae) were collected from Mandapam coastal area, and the seaweeds extracts were tested for in vitro antiplasmodial activity against P. falciparum. Among the tested seaweeds, Gracilaria verrucosa (IC₅₀ 5.55 μg.ml⁻¹) and Hypnea espera (IC₅₀ 8.94 μg.ml⁻¹) showed good antiplasmodial activity, and these results are comparable with positive controls such as artemether (IC₅₀ 4.09 μg.ml⁻¹) and chloroquine (IC₅₀ 19.59 μg.ml⁻¹), respectively. Turbinaria conoides, Sargassum myriocystem, Hypnea valentiae and Jania rubens extracts showed IC₅₀ values between 5 to 50 μg.ml⁻¹. Sargassum sp., Turbinaria decurrens and Halimeda gracilis extracts showed IC₅₀ values between 50 to 100 μg.ml⁻¹. Gracilaria corticata, Jania adherens and Halimeda opuntia extracts showed IC₅₀ value of more than 100 μg.ml⁻¹. Statistical analysis reveals that significant in vitro antiplasmodial activity (P < 0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes was also carried out, and it shows that no morphological changes in erythrocytes by the ethanolic extract of seaweeds extracts after 48 h of incubation. The in vitro antiplasmodial activity might be due to the presence of sugars, proteins, phenols and carboxylic acid in the ethanolic extracts of seaweeds. It is concluded from the present study that the ethanolic extracts of seaweeds of G. verrucosa and Hypnea espera possess lead compounds for development of antiplasmodial drugs.     

In vitro anthelmintic activity of the essential oils of <Emphasis Type="BoldItalic">Zanthoxylum zanthoxyloides</Emphasis> and <Emphasis Type="BoldItalic">Newbouldia laevis</Emphasis> against <Emphasis Type="BoldItalic">Strongyloides ratti</Emphasis>

The need for new anthelmintic with no chemical residues is becoming urgent. In a program aiming at the evaluation of plant as sources of new active molecules, the anthelmintic activities of the essential oils (EOs) obtained from either Zanthoxylum zanthoxyloides seeds or Newbouldia laevis leaves were evaluated against Strongyloides ratti by analyzing the results of two in vitro bioassays. These two plants and their tested parts were retained after an ethnopharmacology survey that confirmed their use by small-scale farmers for treatment of small ruminants affected by digestive helminths. The plants were harvested in Benin, and their EO were obtained by hydrodistillation. The EO yield of extraction was 0.65% (w/w) of for Z. zanthoxyloides seeds and 0.05% (w/w) for N. laevis. The chemical compositions of the two EOs were analyzed by gas chromatography coupled with mass spectrometry. The major constituents of the EO from Z. zanthoxyloides consisted of the following compounds: γ-terpinene (18 %), undecane (15 %), valencene (8.3 %), decanal (8.3 %), and 3-carene (6.7 %). In contrast, the major constituents of the EO from N. laevis leaves consisted of the following compounds: β-caryophyllene (36 %) and eugenol (5.8 %). An egg-hatching inhibition (EHI) assay was developed and a larval migration inhibition assay was used on S. ratti to examine the effects of the EOs and to evidence their inhibitory concentrations (IC₅₀ and IC₉₀) values on this nematode. Furthermore, the toxicity of the two EOs on Vero cell line was evaluated. When tested on S. ratti egg hatching, the two EOs resulted in similar IC₅₀ values (19.5 and 18.2 μg/ml for Z. zanthoxyloides and N. laevis, respectively), which were about sevenfold higher than that of the control (thiabendazole, IC₅₀ = 2.5 μg/ml). Larval migration was inhibited at similar concentrations for: Z. zanthoxyloides (IC₅₀ = 46 μg/ml), N. laevis (IC₅₀ = 51 μg/ml), and the control [levamisole (IC₅₀ = 36 μg/ml)]. No cytotoxicity was found on Vero cells because both EOs had IC₅₀ values higher than 50 μg/ml. Therefore, we have concluded that the EOs from two plants, used in folk medicine, may contain compounds with anthelmintic activity and could be used as improved traditional medicines or, at least, as food additives in a combined treatment for the control of helminth infections.     

Screening of antiplasmodial efficacy of <Emphasis Type="Italic">Ajuga bracteosa</Emphasis> Wall ex. Benth

The rising problem of Plasmodium resistance to the classical antimalarial drugs stresses the need to look for newer antiplasmodial components with effective and new mode of action. In the present study, the traditional medicinal plant Ajuga bracteosa has been screened for its antiplasmodial efficacy. The extract was found to possess significant in vitro antiplasmodial efficacy with an IC₅₀ of 10.0 μg/ml. Thus, the extract was further evaluated for its in vivo schizontocidal activity and efficacy in terms of survival time in Plasmodium berghei infected BALB/c mice. The extract at 250, 500, and 750 mg/kg/day exhibited significant (p < 0.0001) blood schizontocidal activity during established infection with enhanced mean survival time comparable to that of standard drug chloroquine, 5 mg/kg/day. The significant schizontocidal activity and enhanced mean survival time of mice stress the need to identify and characterize active antiplasmodial principle from this plant.     

In vitro antiplasmodial activity of ethanolic extracts of seaweed macroalgae against <Emphasis Type="Italic">Plasmodium falciparum</Emphasis>

Malaria is a major health problem in many developing countries. The drugs resistant Plasmodium falciparum causes the most virulent form of malaria in humans and it is described as a public health disaster causing increased morbidity and mortality. Thirteen seaweeds species which belong to four different families (Rhodomelaceae, Cladophoraceae, Ulvaceae, and Caulerpaceae) were collected from Mandapam coastal area and the seaweeds extracts were tested for in vitro antiplasmodial activity against P. falciparum. Among them, Caulerpa toxifolia (IC₅₀ 5.06 μg·ml⁻¹) showed potential antiplasmodial activity than other seaweeds extracts and it can be comparable with the positive control artemether (IC₅₀ 4.09 μg·ml⁻¹). Caulerpa peltata (IC₅₀ 16.69 μg·ml⁻¹) also exhibited good antiplasmodial activity and the IC₅₀ value is lesser than the positive control chloroquine (IC₅₀ 19.59 μg·ml⁻¹). Statistical analysis reveals that significant in vitro antiplasmodial activity (P < 0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes was also carried out and it shows that no morphological changes in erythrocytes by the ethanolic extract of seaweeds extracts after 48 h of incubation. The in vitro antiplasmodial activity might be due to the presence of sugars, proteins, and phenols in the ethanolic extracts of seaweeds. It is concluded from the present study that, the ethanolic extracts of seaweeds of C. toxifolia and C. peltata possesses lead compounds for development of antiplasmodial drugs.     

Antileishmanial potential of a marine sponge, <Emphasis Type="Italic">Haliclona exigua</Emphasis> (Kirkpatrick) against experimental visceral leishmaniasis

In this study, we are reporting antileishmanial activity of a marine sponge Haliclona exigua, belonging to phylum Porifera. The crude methanol extract and its three fractions were tested both in vitro and in vivo. The crude extract exerted almost complete inhibition of promastigotes at 50 μg/ml and 76.4 ± 6.5% inhibition of intracellular amastigotes at 100 μg/ml concentration with IC₅₀ values of 18.6 μg/ml and 47.2 μg/ml, respectively. When administered to Leishmania donovani infected hamsters at a dose of 500 mg/kg × 5, p.o., it resulted in 72.2 ± 10.4% inhibition of intracellular amastigotes. At a lower dose (250 mg/kg), it exhibited 43.9 ± 5.1% inhibition. Among the fractions, highest antileishmanial activity both in vitro (>90%) and in vivo (60.9 ± 18.3%) was observed in n-butanol (soluble) fraction with IC₅₀ values of 8.2 μg/ml and 31.2 μg/ml against promastigotes and intracellular amastigotes, respectively. Hexane fraction also showed comparatively good activity against both the stages of parasites in vitro but was moderately active in leishmania-infected hamsters. Chloroform fraction resulted in 45 ± 10.2% inhibition in vivo at a dose of 500 mg/kg × 5, p.o., whereas it was inactive in vitro. n-Butanol (insoluble) fraction was inactive both in vitro and in vivo. Araguspongin C, an alkaloid isolated from n-butanol (soluble) fraction exhibited moderate inhibition of promastigotes and intracellular amastigotes at 100 μg/ml but showed weak antileishmanial action in vivo. Our findings indicate that this marine sponge has the potential to provide new lead toward development of an effective antileishmanial agent and, hence, calls for more exhaustive studies for exploiting the vast world of marine resources to combat the scourge of several parasitic diseases.     

Evaluation of antileishmanial potential of Tinospora sinensis against experimental visceral leishmaniasis

The chemotherapeutic interventions against visceral leishmaniasis (VL) are limited and facing serious concerns of toxicity, high cost, and emerging drug resistance. There is a greater interest in new drug developments from traditionally used medicinal plants which offers unprecedented diversity in structures and bioactivity. With this rationale, ethanolic extract of Tinospora sinensis Linn and its four fractions were tested in vitro against promastigotes and intracellular amastigotes and in vivo in Leishmania donovani infected hamsters. Ethanolic extract exhibited an appreciable activity against promastigotes (IC₅₀ 37.6 ± 6.2 μg/ml) and intracellular amastigotes (IC₅₀ 29.8 ± 3.4 μg/ml). In hamsters, it resulted in 76.2 ± 9.2% inhibition at 500 mg/kg/day × 5 oral dose level. Among fractions, n-butanol imparted highest in vitro and in vivo activities. Ethanolic extract and butanol fraction also enhances reactive oxygen species (ROS) and nitric oxide (NO) release. The results indicate that T. sinensis may provide new lead molecules for the development of alternative drugs against VL.     

In vitro antimalarial activity of traditionally used Western Ghats plants from India and their interactions with chloroquine against chloroquine-resistant Plasmodium falciparum

Malaria is a major global public health problem, and the alarming spread of drug resistance and limited number of effective drugs now available underline how important it is to discover new antimalarial compounds. An ethnopharmacological investigation was undertaken on Western Ghats plants traditionally used to treat malaria in India; 50 plants were very carefully selected from a total of 372 plants, and 200 extracts were prepared and tested for in vitro antiplasmodial activity alone and in combination with chloroquine (CQ) against CQ-resistant Plasmodium falciparum (strain MRC-Pf-43). In in vitro antiplasmodial activity, when plant extract alone is used, 29 extracts (or 14.5%) showed significant high in vitro antiplasmodial activity with IC₅₀ values ranging from 3.96 to 4.85 μg/ml, 53 extracts (or 26.5%) showed significant good in vitro antiplasmodial activity with IC₅₀ values ranging from 5.02 to 9.87 μg/ml, and 28 extracts (or 14%) showed significant moderate in vitro antiplasmodial activity with IC₅₀ values ranging from 10.87 to 14 μg/ml, respectively. In combination with CQ, 103 extracts (or 51.5%) showed significant synergistic in vitro antiplasmodial activities with synergistic factor values ranging from 1.03 to 1.92, and these activities were up to a fold higher with CQ, suggesting synergistic interactions of the two drugs. Our investigation has confirmed that above 62.1% of the plant extracts showed moderate to high in vitro antiplasmodial activity when used alone, and in combination with CQ, 55.7% of the extracts showed borderline to good synergistic activity.     

Antiplasmodial activity of triterpenoid isolated from whole plants of <Emphasis Type="Italic">Viola</Emphasis> genus from South Korea

Species of the Viola genus, used in traditional medicines for the treatment of parasites, were collected and petroleum ether extract was obtained by sonication. The antiplasmodial activity of petroleum ether extracts was evaluated in vitro against the chloroquine-resistant FcB1 strain of Plasmodium falciparum. Bioactivity-guided fractionation of the petroleum ether extracts of the whole plants of Viola verecunda has led to the isolation of epi-oleanolic acid, a triterpenoid, displaying high antiplasmodial activity (IC₅₀ 0.18 μg/ml). This is the first report of the isolation and antiplasmodial activity of epi-oleanolic acid from this species.     

Comparative studies of the anti-leishmanial activity of three <Emphasis Type="Italic">Crotalus durissus</Emphasis> ssp. venoms

In this study, we compared the anti-leishmanial activity of three crotalic venoms (Crotalus durissus terrificus–Cdt, Crotalus durissus cascavella–Cdca, and Crotalus durissus collilineatus–Cdcol). Different concentrations of each venom incubated with Leishmania (Leishmania) amazonensis promastigotes were used. Cdt venom exhibited a higher anti-leishmanial activity (Inhibitory concentration-IC50-value of 4.70 ± 1.72 μg/ml) in comparison with that of Cdca venom (IC50 value of 9.41 ± 1.21 μg/ml), while Cdcol venom increased parasite numbers in 50% at a concentration of 44.30 ± 2.18 μg/ml. In addition, this venom showed a low anti-leishmanial activity in higher concentrations (IC50 value of 281.00 ± 9.50 μg/ml). The main fractions of Cdca venom were isolated and assayed under similar conditions used for assessing crude venom. The most active fractions were gyroxin and crotamine that had IC50 values of 3.80 ± 0.52 μg/ml and 19.95 ± 4.21 μg/ml, respectively. Convulxin also inhibited parasite growth rate, although this effect was not dose-dependent. Crotoxin was the least effective fraction with an IC50 value of 99.80 ± 2.21 μg/ml. None of the protein fractions presented cytotoxic effects against J774 cells in culture. In vivo assays using BALB/c mice revealed that crotoxin and crotamine were the main toxic fractions. In conclusion, C. durissus cascavella venom has three main fractions with anti-leishmanial activity. These results open new possibilities to find proteins that might be used as possible agents against cutaneous leishmaniasis.     

Antimalarial drug interactions of compounds isolated from Kigelia africana (Bignoniaceae) and their synergism with artemether, against the multidrug-resistant W2mef Plasmodium falciparum strain

For decades, drug resistance has been the major obstacle in the fight against malaria, and the search for new drugs together with the combination therapy constitutes the major approach in responding to this situation. The present study aims at assessing the in vitro antimalarial activity of four compounds isolated from Kigelia africana stem bark (atranorin - KAE1, specicoside - KAE7, 2β,3β,19α-trihydroxy-urs-12-20-en-28-oic acid – KAE3, and p-hydroxy-cinnamic acid – KAE10) and their drug interactions among themselves and their combination effects with quinine and artemether. The antiplasmodial activity and drug interactions were evaluated against the multidrug-resistant W2mef strain of Plasmodium falciparum using the parasite lactate dehydrogenase assay. Three of the four compounds tested were significantly active against W2mef: specicoside (IC₅₀ = 1.02 ± 0.17 μM), 2β,3β,19α-trihydroxy-urs-12-en-28-oic acid (IC₅₀ = 1.86 ± 0.15 μM) and atranorin (IC₅₀ = 1.78 ± 0.18 μM), whereas p-hydroxy-cinnamic acid showed a weak activity (IC₅₀ = 12.89 ± 0.87 μM). A slight synergistic effect was observed between atranorin and 2β,3β,19α-trihydroxy-urs-12-en-28-oic acid (Combination index, CI = 0.82) whereas the interaction between specicoside and p-hydroxy-cinnamic acid were instead antagonistic (CI = 2.67). All the three compounds showed synergistic effects with artemether, unlike the slight antagonistic interactions of atranorin and 2β,3β,19α-trihydroxy-urs-12-en-28-oic acid in combination with quinine. K. africana compounds are therefore likely to serve as leads in the development of new partner drugs in artemether-based combination therapy.     

The anti-amoebic activity of some medicinal plants used by AIDS patients in southern Thailand

The anti-amoebic activities of chloroform, methanol and water extracts from 12 Thai medicinal plants (39 extracts) commonly used by AIDS patients in southern Thailand were screened, at a concentration of 1,000 μg/ml, against Entamoeba histolytica strain HTH-56:MUTM and strain HM1:IMSS growing in vitro. The extracts were incubated with 2×10⁵ E. histolytica trophozoites/ml of medium at 37°C under anaerobic conditions for 24 h. The cultures were examined with an inverted microscope and scored (1–4) according to the appearance and numbers of the trophozoites. The extracts that caused inhibition were selected and retested using the same conditions but with concentrations that ranged from 31.25 to 1,000 μg/ml using E. histolytica strain HM1:IMSS, and the IC₅₀ values for each extract were calculated. The chloroform extracts from Alpinia galanga (IC₅₀ 55.2 μg/ml), Barleria lupulina (IC₅₀ 78.5 μg/ml), Boesenbergia pandurata (IC₅₀ 45.8 μg/ml), Piper betle (IC₅₀ 91.1 μg/ml) and Piper chaba (IC₅₀ 71.4 μg/ml) and the methanol extract from B. pandurata (IC₅₀ 57.6 μg/ml) were all classified as “active”, i.e. with an IC₅₀ of less than 100 μg/ml, whereas those from Murraya paniculata (IC₅₀ 116.5 μg/ml) and Zingiber zerumbet (IC₅₀ 196.9 μg/ml) were classified as being “moderately active”. The IC₅₀ of a standard drug, metronidazole, was 1.1 μg/ml.     

In vitro antiplasmodial activity of ethanolic extracts of mangrove plants from South East coast of India against chloroquine-sensitive Plasmodium falciparum

Malaria is one of the most prevalent infectious diseases in the world. Treatment for malaria is commonly inadequate due to the lack of quality assured effective drugs. The effectiveness of these drugs is declining at an ever accelerating rate, with consequent increase in malaria related morbidity and mortality. The newest antiplasmodial drug from plants is needed to overcome this problem. Numerous mangroves and mangal associates are used as folklore medicine to treat various human diseases. The mangrove plant species are a good source of potential bioactive entities which exhibits many therapeutic properties. The present study was carried out to test the antiplasmodial activity of five mangrove plant species distributed along the South East coast of India. Bruguiera cylindrica, Ceriops decandra, Lumnitzera racemosa, Rhizophora apiculata, and Rhizophora mucronata mangrove plant extracts exhibited in vitro antiplasmodial activity against chloroquine-sensitive Plasmodium falciparum. Of which, the ethanolic bark extract of R. mucronata exhibited high antiplasmodial activity (IC₅₀ = 62.18 μg.ml⁻¹). Statistical analysis reveals that, significant antiplasmodial activity (P < 0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes was also carried out and it shows that no morphological differences in erythrocytes by the ethanolic extract of mangrove plants after 48 h of incubation. The screening for phytochemical constituents in the mangrove plants were carried out and it reveals that, the presence of alkaloids, triterpenes, flavonoids, tannins, catachin, anthroquinone, phenols, sugars, and proteins. This study shows that the mangrove plants had a source of lead compounds for the development of new drugs for the treatment of malaria.     

In vitro evaluation of the effectiveness and cytotoxicity of meglumine antimoniate microspheres produced by spray drying against Leishmania infantum

The aim of the present study was to evaluate the in vitro activity and cytotoxicity of meglumine antimoniate microspheres produced by spray drying on Leishmania infantum and the effect of the excipients used in them. The parasite strain shows sensitivity to the meglumine antimoniate microspheres prepared. All the antimony IC₅₀ values from encapsulated meglumine antimoniate (3.80 ± 0.34 to 9.53 ± 0.70 μg SbV/ml for promastigotes assay) are considerably lower compared to the mean value of IC₅₀ in Glucantime solution (112 ± 12.74 μg SbV/ml). Interesting IC₅₀ values for the excipient chitosan (112.64 ± 0.53 mg/ml for promastigotes and 100.81 ± 26.45 mg/ml for amastigotes) were obtained (without cytotoxic activity), whereas the rest of the excipients did not show any activity. This new delivery system could offer a new pharmacological tool for the treatment of leishmaniosis that reduces the doses required, lowering toxic side effects because of meglumine antimoniate.     

In vitro and in vivo trypanocidal activity of native plants from the Yucatan Peninsula

Ethanol extracts of Senna villosa, Serjania yucatanensis, Byrsonima bucidaefolia, and Bourreria pulchra were evaluated for their in vitro activity against epimastigotes and trypomastigotes of Trypanosoma cruzi. Results showed that the leaf extracts of S. yucatanensis and B. pulchra were the most active against epimastigotes (IC₁₀₀ = 100 μg/mL) and trypomastigotes of T. cruzi (95% or more reduction in the number of parasites at 100 and 50 μg/mL). However, only the leaf extract of S. yucatanensis showed significant trypanocidal activity when tested in vivo, reducing 75% of the parasitemia in infected mice at 100 mg/kg. This same extract inhibited the egress of trypomastigotes from infected cells and proved not to be cytotoxic (IC₅₀ = 318.8 ± 2.3 μg/mL).     

Gedunin and photogedunin of Xylocarpus granatum possess antifilarial activity against human lymphatic filarial parasite Brugia malayi in experimental rodent host

The present study is aimed to evaluate antifilarial activity of Xylocarpus granatum (fruit from Andaman) against human lymphatic filarial parasite Brugia malayi in vivo. The in vitro antifilarial activity has already been reported earlier for this mangrove plant which has traditionally been used against several ailments. Aqueous ethanolic crude extract, four fractions (ethyl acetate fraction, n-butanol fraction, water-soluble fraction and water-insoluble fraction) and pure molecule/s of X. granatum (fruit) were tested in vitro on adult worms and microfilariae (mf) of B. malayi and the active samples were further evaluated in vivo in B. malayi (intraperitoneally) i.p. transplanted in the jird model (Meriones unguiculatus) and Mastomys coucha subcutaneously infected with infective larvae (L3). The crude aqueous ethanolic extract was active in vitro (IC50: adult = 15.46 μg/ml; mf = 13.17 μg/ml) and demonstrated 52.8% and 62.7% adulticidal and embryostatic effect on B. malayi, respectively, in Mastomys at a dose of 5 × 50 mg/kg by oral route. The antifilarial activity was primarily localized in the ethyl acetate-soluble fraction which revealed IC50 of 8.5 and 6.9 μg/ml in adult and mf, respectively. This fraction possessed moderate adulticidal and embryostatic action in vivo in Mastomys. Out of eight pure molecules isolated from the active fraction, two compounds gedunin (IC50 = 0.239 μg/ml, CC50 = 212.5 μg/ml, SI = 889.1) and photogedunin (IC50 = 0.213 μg/ml, CC50 = 262.3 μg/ml, SI = 1231.4) at 5 × 100 mg/kg by subcutaneous route revealed excellent adulticidal efficacy resulting in to the death of 80% and 70% transplanted adult B. malayi in the peritoneal cavity of jirds respectively in addition to noticeable microfilaricidalo action on the day of autopsy. The findings reveal that the extract from the fruit X. granatum contains promising in vitro and in vivo antifilarial activity against human lymphatic filarial parasite B. malayi which could be attributed to the presence of two pure compounds gedunin and photogedunin.     

In vitro and in vivo activity of <Emphasis Type="Italic">Aloe vera</Emphasis> leaf exudate in experimental visceral leishmaniasis

The leishmanicidal activity of Aloe vera leaf exudate (AVL) has been demonstrated in promastigotes and axenic amastigotes, but its effectiveness in animal models has not been evaluated. The presence of alkaloids, triterpenes, cyanidines, proanthocyanidines, tannins, and saponins in AVL was identified. Its effectiveness in four Leishmania donovani strains was studied both in promastigotes (IC₅₀ ranged from 70–115 μg/ml) and amastigotes (IC₅₀ ranged from 3.1–11.4 μg/ml). In amastigotes, the killing by AVL was facilitated through its induction of nitric oxide in leishmania-infected macrophages. The safety index was good as AVL up to 300 μg/ml remained non-toxic to monocytes and macrophages. In a L. donovani BALB/c mouse model, oral or subcutaneous administration of AVL (15 mg/kg body weight × 5 days) reduced parasitemia by >90% in the liver, spleen, and bone marrow without impairment of hepatic and renal functions. Collectively, we conclude that AVL shows promising antileishmanial activity and may provide a new lead agent in the treatment of Leishmaniasis. Chitra Mandal and Mitali Chatterjee should be considered as joint senior authors.