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.     

Essential oils of indigenous in Greece six <Emphasis Type="BoldItalic">Juniperus</Emphasis> taxa

The chemical composition of 14 essential oils (EOs), obtained from various parts (leaves, fruits, wood) of the six indigenous in Greece Juniperus family taxa, was determined by GC and GC/MS analysis. The insecticidal properties of these EOs were evaluated against Culex pipiens L. larvae of 3rd and early 4th instars, in order to delineate the relationship between the phytochemical content of the EOs and their larvicidal activities. The analytical data indicated that the EOs mainly consisted of monoterpenes, mostly cyclic and only occasionally aliphatic, and to a lesser percent, of diterpenes. The larvicidal bioassays against C. pipiens larvae revealed that the most active EO was derived from the wood of Juniperus drupacea and contains mainly non-oxygenated monoterpenes and a significant amount of diterpenes, displaying the highest chemodiversity. Its initial LC₅₀ value was 26.47 mg L⁻¹. On the contrary, the EO isolated from J. phoenicea berries, which consisted of monoterpenes (non-oxygenated, cyclic), was the less active displaying an LC₅₀ value of 96.69 mg L⁻¹. In respect to the contained phytochemicals, myrcene was assayed as the most toxic, displaying an LC₅₀ value of 33.83 mg L⁻¹, while the four isomers of pinene abundant in all EOs were less active exhibiting LC₅₀ values ranging from 70.40 to 94.88 mg L⁻¹. Results herein reveal that the EOs isolated from the studied Juniperus family taxa represent an inexpensive source of natural mosquito control mixtures.     

Anthelmintic effect of a methanol extract of <Emphasis Type="Italic">Bombax malabaricum</Emphasis> leaves on <Emphasis Type="Italic">Paramphistomum explanatum</Emphasis>

Bombax malabaricum (family Bombacaceae) is used as anthelmintic in traditional system of medicine in Southern Punjab of Pakistan. The objective of this study was to evaluate the anthelmintic activity of the methanol extract of B. malabaricum leaves (MEBM). Live parasites (trematode: Paramphistomum explanatum) were collected from buffalo in 0.9% phosphate-buffered saline. It was incubated in Petri dishes at 37 ± 1°C in media containing either no extract (control) or MEBM, the test drug at 10, 25, 50, and 100 mg/ml dose level or albendazole, the standard drug at 10 mg/ml. The efficacy of the extract or albendazole was measured on the basis of the loss of spontaneous movement and/or death of the trematodes. Paralysis was considered when there is no movement unless shaken vigorously. Death was confirmed when the trematodes completely lost their motility, even when vigorously shaken or dipped in warm water (50°C), followed by fading away of their body color. The trematodes, both drug treated and others, were further processed for SEM study using the standard method. All trematodes died with all the above-mentioned doses of MEBM within a short period of time (less than 45 min) which was statistically highly significant (p < 0.001). MEBM at 100 mg/ml showed maximum efficacy. It paralyzed and killed trematodes in 18.50 ± 0.62 and 22.17 ± 0.48 min, respectively. SEM study showed that MEBM-treated trematodes were stretched. The study established the anthelmintic activity of MEBM.     

In vitro activity of the essential oil of <Emphasis Type="Italic">Cymbopogon citratus</Emphasis> and its major component (citral) on <Emphasis Type="Italic">Leishmania amazonensis</Emphasis>

Leishmaniasis causes considerable mortality throughout the world, affecting more than 12 million people. Cymbopogon citratus (DC) Stapf, Family Poaceae, is a widely used herb in tropical countries and is also known as a source of ethnomedicines. In this study, the inhibitory effect and the morphological and ultrastructural alterations on Leishmania amazonensis by the essential oil (EO) of C. citratus and its main constituent, citral, were evaluated. The results showed that the antiproliferative activity of EO on promastigotes and axenic amastigotes, and intracellular amastigote forms of L. amazonensis was significantly better than citral, and indicated a dose-dependent effect. Neither compound showed a cytotoxic effect on macrophage strain J774G8. The promastigote forms of L. amazonensis underwent remarkable morphological and ultrastructural alterations compared with untreated cultures. These alterations were visible by light, scanning, and transmission electron microscopy of promastigotes treated with EO and citral at concentrations corresponding to the IC₅₀ (1.7 and 8.0 μg/ml) and IC₉₀ (3.2 and 25 μg/ml), respectively, after 72 h of incubation. This study revealed that citral-rich essential oil from C. citratus has promising antileishmanial properties, and is a good candidate for further research to develop a new anti-protozoan drug.     

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.     

Anti-leishmania activity of semi-purified fraction of <Emphasis Type="Italic">Jacaranda puberula</Emphasis> leaves

The crude methanolic extract from leaves of Jacaranda puberula showed activity against Leishmania (Leishmania) amazonensis. The extract presented active against promastigote forms with an inhibitory concentration 50% (IC₅₀) value of 88.0 μg/ml, but only moderated activity against amastigote forms; however in higher concentrations the extract showed cytotoxic effects. The bio-guided chromatographic fractionation the crude methanolic extract against amastigotes yielded a fraction with an IC₅₀ value of 14.0 μg/ml (without cytotoxic activity) in relation to the crude extract (IC₅₀ value, 359.0 μg/ml). These data indicate that J. puberula leaves contain active compounds, which should be further investigated for the development of new potential drugs against cutaneous leishmaniasis.     

Bioactivity of essential oils of <Emphasis Type="BoldItalic">Zingiber officinalis</Emphasis> and <Emphasis Type="BoldItalic">Achyranthes aspera</Emphasis> against mosquitoes

Due to the global health problems associated with mosquito-borne diseases, over two million people primarily in the tropical countries are at risk. The widely and commonly used chemical method though effective, has some major disadvantages making insect control practically difficult. In view of the above, it is unavoidable to search for new molecules, which are eco-friendly, cheaper, and safer. The present study deals with evaluation of bioactive potential of two commonly occurring plants against mosquitoes presenting an alternative to the conventional chemical methods. Essential oils extracted by steam distillation from rhizome of Zingiber officinalis and leaf and stem of Achyranthes aspera were evaluated for larvicidal, attractant/repellent, and oviposition attractant/deterrent activity against two mosquito species viz. Aedes aegypti and Culex quinquefasciatus. The highest larvicidal activity, i.e., LC₅₀ = 154 ppm and LC₅₀ = 197 ppm for A. aegypti and C. quinquefasciatus, respectively was shown by Z. officinalis. This oil also offers 5-h protection at the concentration of 0.5 mg/cm2 from both mosquito species. The highest oviposition deterrence activity was exhibited by A. aspera stem oil, i.e., 100% and 85.71%, in case of A. aegypti and C. quinquefasciatus, respectively, at the concentration of 0.1%. These results reveal that both these oils have control potential against A. aegypti and C. quinquefasciatus.     

Insecticidal Evaluation of essential oils of <Emphasis Type="BoldItalic">Citrus sinensis</Emphasis> L. (Myrtales: Myrtaceae) against housefly, <Emphasis Type="BoldItalic">Musca domestica</Emphasis> L. (Diptera: Muscidae)

The housefly, Musca domestica L., is one of the most common insects, associated with vectoring of various etiological agents. In order to search for effective control agent, the essential oil of sweet orange [Citrus sinensis (L.) Osbeck] was evaluated for its insecticidal activity against the larvae and pupae of housefly using contact toxicity and fumigation bioassays. In the contact toxicity assay, lethal concentration, LC₅₀ of C. sinensis essential oil against housefly larvae, varied between 3.93 and 0.71 μl/cm² for different observation days, while lethal time, LT₅₀, varied between 5.8 to 2.3 days. Mortality of larvae were significant with different concentrations (F = 2.79, df = 4, P < 0.05) and time (F = 6.69, df = 3, P < 0.01). In fumigant assay for housefly larvae, LC₅₀ of 71.2 and 52.6 μl/l was obtained in 24 and 48 h, respectively. Scanning electron microscopy of oil treated larvae revealed extreme dehydration and surface distortion while control larvae were free from any of the above symptoms and presented smooth surface, conforming effect of essential oil on housefly larvae. Percentage inhibition rate of oil against housefly pupae was 27.3–72.7% for contact toxicity and 46.4–100% for fumigation assay. Compositional analysis of C. sinensis essential oil using gas chromatography/mass spectrometry (GC-MS) revealed d-limonene (73.24%), α-pinene (5.86%) and myrcene (4.45%) as major components whereas its vapour profile (solid-phase micro extraction-GC/MS) was dominated by d-limonene at 92.57%. Significant activity of C. sinensis essential oil against larvae and pupae of housefly, pave the way for its use as eco-friendly housefly control measure.     

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.     

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.     

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.     

Antiprotozoan activity of Brazilian marine cnidarian extracts and of a modified steroid from the octocoral <Emphasis Type="Italic">Carijoa riisei</Emphasis>

In the present investigation, we have evaluated the antileishmanial and antitrypanosomal activity of methanolic crude extracts obtained from eight species of cnidarians and of a modified steroid isolated from the octocoral Carijoa riisei. The antileishmanial activity of cnidarians crude extracts showed 50% inhibitory concentration (IC₅₀) values in the concentration range between 2.8 and 93.3 μg/mL. Trypomastigotes of Trypanosoma cruzi were less susceptible to the crude extracts, with IC₅₀ values in the concentration range between 40.9 and 117.9 μg/mL. The steroid (18-acetoxipregna-1,4,20-trien-3-one) displayed a strong antileishmanial activity, with an IC₅₀ value of 5.5 μg/mL against promastigotes and 16.88 μg/mL against intracellular amastigotes. The steroid also displayed mammalian cytotoxicity (IC₅₀ of 10.6 μg/mL), but no hemolytic activity was observed at the highest concentration of 12.5 μg/mL. The antileishmanial effect of the steroid in macrophages suggested other mechanism than macrophage activation, as no upregulation of nitric oxide was observed. The antitrypanosomal activity of the steroid resulted in an IC₅₀ value of 50.5 μg/mL. These results indicate the potential of cnidarian natural compounds as antileishmanial drug candidates.     

Antileishmanial activity of crude extract and coumarin from <Emphasis Type="Italic">Calophyllum brasiliense</Emphasis> leaves against <Emphasis Type="Italic">Leishmania amazonensis</Emphasis>

Infections by protozoans of the genus Leishmania are a major worldwide health problem, with high endemicity in developing countries. The drugs of choice for the treatment of leishmaniasis are the pentavalent antimonials, which show renal and cardiac toxicity. As part of a search for new drugs against leishmaniasis, we evaluated the in vitro leishmanicidal activity of the (−) mammea A/BB. The compound (−) mammea A/BB is a coumarin-type mammea purified from a dichloromethane crude extract of leaves of Calophyllum brasiliense Cambess (Clusiaceae). The isolated compound was characterized using spectral analyses by UV, infrared, nuclear magnetic resonance of ¹H, ¹³C, distortionless enhancement by polarization transfer, correlation spectroscopy, heteronuclear multiple bond correlation, and heteronuclear multiple quantum coherence. The compound (−) mammea A/BB showed significant activity against promastigote and amastigote forms of L. amazonensis, with IC₅₀ (50% inhibition concentration of cell growth) at a concentration of 3.0 and 0.88 μg/ml and IC₉₀ (90% inhibition concentration of cell growth) of 5.0 and 2.3 μg/ml, respectively. The coumarin (−) mammea A/BB showed no cytotoxicity against J774G8 macrophages in culture, when it was tested at high concentrations that inhibited promastigote forms. Electron microscopy studies revealed considerable ultrastructural changes when promastigote forms of L. amazonensis were treated with 3.0 μg/ml of the coumarin (−) mammea A/BB for 72 h. We observed significant changes such as mitochondrial swelling with concentric membranes in the mitochondrial matrix and intense exocytic activity in the region of the flagellar pocket. Other alterations included the appearance of binucleate cells and multiple cytoplasmic vacuolization. These results showed that (−) mammea A/BB is a potent growth inhibitor of L. amazonensis and caused important changes in the parasite’s ultrastructure. This study provided new perspectives on the development of novel drugs with leishmanicidal activity obtained from natural products.     

The effect of verapamil on in vitro susceptibility of promastigote and amastigote stages of <Emphasis Type="Italic">Leishmania tropica</Emphasis> to meglumine antimoniate

Pentavalent antimonials are the standard treatment for cutaneous leishmaniasis (CL) with low efficacy and resistance is emerging. CL is increased significantly in respect to incidence rate and expanding to new foci. In the present study, the effect of verapamil on in vitro susceptibility of promastigote and amastigote stages of Leishmania tropica to meglumine antimoniate (MA, Glucantime) was evaluated using colorimetric assay (MTT) and in a macrophage model, respectively. Verapamil, as a calcium channel blocker, affects drug uptake by preventing of drug efflux from the cells. In promastigote form, several concentrations of MA with or without verapamil showed significant decrease (P < 0.05) in optical density. The overall mean IC₅₀ value with combination of MA plus verapamil (IC50 = 116.03 μg/ml) was significantly less than MA (IC50 = 225.14 μg/ml) alone (P < 0.05) for promastigote stage. Similarly, the amastigote stage was more susceptible to treatment with MA plus verapamil to that of MA alone (P < 0.05). Analysis of overall effect of different concentrations of MA alone, compared with combination of MA plus verapamil by mean infection rate of amastigotes in each macrophage showed a significant difference (P < 0.05).These findings indicated some degree of synergistic effects between MA and verapamil on in vitro susceptibility of L. tropica to MA. Further works are required to evaluate this synergistic effect on animal model or volunteer human subjects.     

Efficacy of the <Emphasis Type="Italic">Trichophyton ajelloi</Emphasis> and <Emphasis Type="Italic">Lagenidium giganteum</Emphasis> metabolites against mosquitoes after flash chromatography

Entomopathogens are significant natural enemies for mosquitoes. We have investigated the adulticidal efficacies of metabolites of Trichophyton ajelloi and Lagenidium giganteum against Culex quinquefasciatus and Aedes aegypti simultaneously. The T. ajelloi was grown on Sabouraud’s dextrose broth medium at 25 ± 2°C and relative humidity at 75 ± 5% for 15 days. L. giganteum was grown in peptone yeast extract glucose broth at 25 ± 2°C and relative humidity 75 ± 5% for 15 days. The filtrations of metabolites have been made by using Whatman-1 filter paper then with the flash chromatograph. The bioassays were conducted as per the World Health Organization’s methods and protocols (2006). In this significant investigations, the metabolites of T. ajelloi have been found highly susceptible against A. aegypti with LC₉₉-7.24 ml after an exposure time of 24 h with a comparison, the LC₉₉-66 ml was observed against C. quinquefasciatus after exposure of 24 h. Moreover, the L. giganteum metabolites have shown higher pathogenicity against C. quinquefasciatus with LC₉₉-11.3 ml and A. aegypti with LC₉₉-15.49 ml. Although, the efficacy in adults could be achieved with higher concentration can be significant also. Their adulticidal activities in different climatic zones are plausible with metabolites which have better LT values of T. ajelloi.     

Larvicidal efficacy of <Emphasis Type="Italic">Jatropha curcas</Emphasis> and bacterial insecticide, <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis>, against lymphatic filarial vector<Emphasis Type="Italic">, Culex quinquefasciatus</Emphasis> Say (Diptera: Culicidae)

The present study explored the effects of Jatropha curcas leaf extract and Bacillus thuringiensis israelensis larvicidal activity against the lymphatic filarial vector, Culex quinquefasciatus. Wights were selected for investigating the larvicidal potential against the first to fourth instar larvae of the laboratory-reared mosquito species, C. quinquefasciatus Say, in which the major lymphatic filariasis was used. The medicinal plants were collected from the area around Bharathiar University, Coimbatore. The dried plant materials were powdered by an electric blender. From the powder, 100 g of the plant materials was extracted with 300 ml of organic solvents of methanol for 8 h, using a Soxhlet apparatus, and filtered. The crude plant extracts were evaporated to dryness in a rotary vacuum evaporator. The plant extract showed larvicidal effects after 24 h of exposure; however, the highest larval mortality was found in the leaf extract of methanol J. curcas against the first to fourth instar larvae of values LC₅₀ = 1.200%, 1.290%, 1.358%, and 1.448% and LC₉₀ = 2.094%, 2.323%, 2.444%, and 2.544% and B. thuringiensis israelensis against the first to fourth instar larvae of values LC₅₀ = 9.332%, 9.832%, 10.212%, 10.622% and LC₉₀ = 15.225%, 15.508%, 15.887%, and 15.986% larvae of C. quinquefasciatus, respectively. No mortality was observed in the control. These results suggest methanol extracts of J. curcas and B. thuringiensis israelensis have potential to be used as an ideal eco-friendly approach for the control of the major lymphatic filarial vector, C. quinquefasciatus.     

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.     

A novel herbal formulation against dengue vector mosquitoes <Emphasis Type="Italic">Aedes aegypti</Emphasis> and <Emphasis Type="Italic">Aedes albopictus</Emphasis>

The objective of this study was to develop a herbal formulation to control dengue vector mosquitoes. PONNEEM, a novel herbal formulation prepared using the oils of neem (Azadirachta indica), karanj (Pongamia glabra) and their extracts, was tested for larvicidal, ovicidal and oviposition deterrent activities against Aedes aegypti and Aedes albopictus at 1, 0.5, 0.3 and 0.1 ppm concentrations. Cent percent larvicidal and ovicidal activities were observed at 0.1 ppm in the two mosquito species under laboratory and sunlight-exposed conditions up to 12 months from the date of manufacture. Oviposition deterrent activity of 69.97% and 71.05% was observed at 1 ppm concentration of PONNEEM against A. aegypti and A. albopictus, respectively. Reduction in enzyme levels for α-esterase was 0.089 ± 0.008 and 0.099 ± 0.140 μg napthol produced/min/mg larval protein; for β-esterase, it was 0.004 ± 0.009 and 0.001 ± 0.028 μg napthol produced/min/mg larval protein; for glutathione S-transferase, it was 10.4814 ± 0.23 and 11.4811 ± 0.21 μmol/min/mg larval protein and for total protein, it was 0.177 ± 0.010 and 0.008 ± 0.005 mg/individual larva in treated groups of A. aegypti and A. albopictus, respectively. The nontarget organisms such as Gambusia affinis and Diplonychus indicus were not affected. No mortality was observed in control. PONNEEM can be used effectively for the management of human vector mosquitoes.     

Anthelmintic activity of <Emphasis Type="Italic">Spigelia anthelmia</Emphasis> extract against gastrointestinal nematodes of sheep

In vitro (larval development assay) and in vivo studies were conducted to determine possible direct anthelmintic effect of ethanolic and aqueous extracts of Spigelia anthelmia towards different ovine gastrointestinal nematodes. The effect of extracts on development and survival of infective larvae stage (L₃) was assessed. Best-fit LC₅₀ values were computed by global model of non-linear regression curve fitting (95% confidence interval). Therapeutic efficacy of the ethanolic extracts administered orally at a dose rate of 125, 250, and 500 mg/kg, relative to a non-medicated control group of sheep harbouring naturally acquired infection of gastrointestinal nematodes, was evaluated in vivo. The presence of S. anthelmia extracts in the cultures decreased the survival of L₃ larvae. The LC₅₀ of aqueous extract (0.714 mg/ml) differ significantly from the LC₅₀ of the ethanolic extract (0.628 mg/ml) against the strongyles (p < 0.05, paired t-test). Faecal egg counts on day 12 after treatment showed that the extract is effective, relative to control (one-way analysis of variance [ANOVA], Dunnett’s multiple comparison test) at 500 mg/kg against Strongyloides spp. (p < 0.01), 250 mg/kg against Oesophagostomum spp., Trichuris spp. (p < 0.05), and 125 mg/kg against Haemonchus spp. and Trichostrongylus spp. (p < 0.01). The effect of the doses is significant in all cases, the day after treatment is also extremely significant in most cases, whereas interaction between dose and day after treatment is significant (two-way ANOVA). S. anthelmia extract could, therefore, find application in the control of helminth in livestock, by the ethnoveterinary medicine approach.     

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.