Plasmodium Berghei Infection Research Articles

The TCR Takes Some Immune Responsibility

In this issue of Immunity, Van Braeckel-Budimmir etal. (2017) reveal that the pathogenic response of mice to a Plasmodium berghei infection is dominated by a Vβ8.1 Tcell response. Mice lacking Vβ8.1 Tcells fail to mount a pathogenic response, thus showing that the TCR locus can be an Immune response (Ir) gene.

Anti-plasmodial and anti-inflammatory activities of cyclotide-rich extract and fraction of Oldenlandia affinis (R. & S.) D.C. (Rubiaceae).

Oldenlandia affinis, commonly called 'kalata-kalata', a versatile plant used locally to treat malaria fever in some parts of sub-Saharan Africa was investigated for anti-plasmodial and anti-inflammatory activities. The study was designed to evaluate the antiplasmodial as well as anti-inflammatory activities of whole extract and cyclotide-rich fraction of Oldenlandia affinis. The dichloromethane-methanol extract (ODE) of the plant, O. affinis was investigated for suppressive and curative antiplasmodial activities against Plasmodium berghei in mice. ODE and the cyclotide-rich fraction (CRF) was investigated for chronic and acute anti-inflammatory activities in rat models of inflammation. Inhibition of pro-inflammatory mediators was studied in RAW264.7 macrophages. ODE exhibited significant (p<0.05) reduction in mean parasitaemia in both the suppressive and curative models of Plasmodium berghei infection in mice.Administration of ODE(100, 200, or 400 mg/kg) and CRF (100, 200, or 400 mg/kg) produced significant inhibition of rodent models of acute and chronic inflammation . This observation is supported by the significant (P<0.05) inhibition of pro-inflammatory mediators, inducible nitric oxide (iNO) and tumour necrosis factor-alpha (TNF-α), and the reactive radical scavenging activities in RAW264.7 macrophages. These findings could explain, at least in part, the successes reported in the use of the herb, Oldenlandia affinis in the traditional treatment of malaria fever.

Chemopreventive and remediation effect of Adansonia digitata L. Baobab (Bombacaceae) stem bark extracts in mouse model malaria

Ethnopharmacological relevanceAdansonia digitata L. Baobab (Bombacaceae) solvent extracts have been reported to possess medicinal properties and are currently been used traditionally for the treatment of malaria and several other diseases and infection; however few reports exist in literature that provides supportive scientific evidence in favour of its medicinal use. Aim of the studyThis study investigated the efficacy of Adansonia digitata stem bark extract in offering protection against experimental malaria and also examined its remediation effect when administered after established infection. Materials and methodsWeanling albino mice were used in the study. The mice were transfected intraperitonially with an inoculums size of 1× 107 of chloroquine susceptible strain of plasmodium berghei infected erythrocytes. Mechanisms of action of the extract were investigated by measuring the degree of tissue peroxidation and tissue antioxidant status. Severity of malaria was determined by measuring the serum C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), and serum and tissue Alkaline phosphatase (ALP) activity. ResultsThere was a significant increase in serum CRP, TNF-α concentrations and serum and tissue ALP activity in the control mice following Plasmodium berghei infection. All the treatment had effect on the growth of Plasmodium berghei parasites in mice. The extracts showed a significant dose dependent increase packed cell volume (PCV), percentage chemosupression/clearance and a significant decrease in percentage parasitemia at the two doses when administered after established infection. Methanolic extract (MEAD) at 400mg/kg exhibited the highest chemosupressive activity. The extract significantly reduced the degree of tissue peroxidation, increased the level of reduced glutathione (GSH), catalase and superoxide dismutase activity. Administration of the extract after established infection reduced serum CRP and TNF-α concentrations and serum and tissue ALP activity. ConclusionOur study suggests that Adansonia digitata protects against Plasmodium berghei induced-malaria, and that administration of the extract after established infection reduced malaria progression.

Investigating the role of bone marrow stroma in the response of haematopoietic stem cells to plasmodium berghei infection

Haematopoietic stem cells (HSCs) maintain the turnover of all blood cell lineages and reside within the bone marrow (BM), where they are critically dependant on interactions with complex and specialised niches. Infection can have profound effects on haematopoiesis. HSCs tend to adapt their progeny output to promptly cope with the increased need for immune cells, which often leads to exhaustion of the stem cell pool. It has been shown that chronic infections result in a loss of HSC function (1), whereas acute infections induce more transient perturbations (2). Questions remain about how the HSC response contributes to stressed haematopoiesis and whether it may affect HSC function in the long-term; how the transition from stem cell to progenitor cell changes in an infected setting; and whether the changes observed are mediated by alterations in the BM niche. Using a mouse model of malaria, based on the natural route of sporozoite inoculation by the bites of mosquitos infected with Plasmodium berghei, we are able to investigate these questions and gain an insight into haematopoietic perturbations as infection progresses. We have previously shown that P. berghei infection has significant effects on progenitor cells, while HSC numbers remain largely unchanged (3). Here I demonstrate that HSC function is maintained through infection, using BM transplantation assays, and this is despite the fact that their proliferation is dramatically altered - as early as the liver stage of infection, before parasitemia is detectable in the blood. I hypothesise that this may be mediated by profound alterations of the BM microenvironment and use intravital confocal 2-photon imaging of calvarium BM in control and infected mice to visualise the effects of P. berghei on various niche components.

Response of outbred albino mice to concomitant Heligmosomoides bakeri, Plasmodium berghei and Trypanosoma brucei infections.

To investigate the response of mice to concomitant infections with Trypanosoma brucei (Tb), Plasmodium berghei (Pb) and Heligmosomoides bakeri (Hb) infections. Each group of 6 mice was either infected with Pb+Tb+Hb, Pb+Tb, Pb+Hb, Tb+Hb, Pb, Tb, Hb or remained as uninfected controls. Hb infected mice each received 200 infective larvae (L3) of Hb orally, Tb infected mice each received 2×10-6 organisms through the intraperitoneal route while Pb infected mice received 1×10-5 parasitized red blood cells through the intraperitoneal route. PCV, body weights (BW), faecal egg counts (FEC), Tb parasitaemia, Pb parasitaemia, clinical signs and worm burdens (WB) were determined. FEC were highest in Pb+Tb+Hb and least in Hb group and the difference was significant (P<0.05). WB was significantly higher in mice with concurrent infections. PCV of infected mice was lower than that of uninfected controls and the difference was significant between Pb+Tb+Hb infected and uninfected controls. The difference in weight loss was significant between Pb+Tb+Hb infected and controls. Mortalities occurred in Pb+Tb+Hb, Tb+Hb and Pb+Hb infected mice. Mortalities and low PCV and low BW were indications that concomitant infections were more pathogenic to the mice than single infections, pathogenicity increasing with increasing number of parasite species involved.

Modulation of Midgut Peritrophins' Expression during &lt;i&gt;Plasmodium Infection&lt;/i&gt; in &lt;i&gt;Anopheles stephensi&lt;/i&gt; (Diptera:Culicidae)

The peritrophic matrix (PM) serves as a barrier to pathogens in many disease vectors including mosquitoes. The Plasmodium ookinete has to cross the PM barrier for its successful establishment in the mosquito midgut and subsequent transmission. It is conceived that alterations to PM may lead to a block in infection. Peritrophins which are the major constituents of PM are yet to be elucidated at molecular level. The present study demonstrates Anopheles stephensi midgut peritrophins' expression during Plasmodium berghei infection. Eight peritrophin genes ( Per 10, Per 16, Per 22, Per 25, Per 26, Per 28, Per 30 & Per 43 ) of A. stephensi were identified from vectorbase, isolated from the adult midgut, and expression pattern monitored in real-time, in normal and infected blood meal conditions. Temporal expression of peritrophins in the midgut was monitored every 6 h till 24 h post blood meal. Results showed that the Per 10, Per 16, Per 22, Per 25 and Per 26 expression was significantly downregulated during Plasmodium infection whereas Per 30 and Per 43 expression was markedly up-regulated. The Per 28 expression was low initially but elevated later. This data clearly indicates that peritrophins are differentially modulated in infected midgut. The significance of differential expression of peritrophins' in parasite transmission is discussed further.

Evidence of cross-stage CD8+ T cell epitopes in malaria pre-erythrocytic and blood stage infections.

Malaria parasites have a complex, multistage life cycle and there is a widely held view that each stage displays a distinct set of antigens presented to the immune system. Yet, molecular analysis of malaria parasites suggests that many putative antigenic targets are shared amongst the different stages. The specificities of these cross-stage antigens and the functions of the immune responses they elicit are poorly characterized. It is well-known that CD8+ T cells play opposing immune functions following Plasmodium berghei (Pb) infection of C57BL/6 mice. Whilst these cells play a crucial role in protective immunity against pre-erythrocytic stages, they are implicated in the development of severe disease during blood stages. Recently, CD8+ T cell epitopes derived from proteins supposedly specific for either pre-erythrocytic or blood stages have been described. In this brief report, we have compiled and confirmed data that the majority of the mRNAs and/or proteins from which these epitopes are derived display expression across pre-erythrocytic and blood stages. Importantly, we provide evidence of cross-stage immune recognition of the majority of these CD8+ T cell epitopes. Hence, our findings provide a resource to further examine the relevance of antigen-specific cross-stage responses during malaria infections.

Antiplasmodial activity of Indigofera spicata root extract against Plasmodium berghei infection in mice

BackgroundIn addition to pharmacovigilance and pharmaco-economic concerns, resistance to anti-malarial medicines has been documented in all classes of anti-malarials and this is further worsened by resistance to common insecticides by malaria vector, which is a major threat to malaria control. As a means of facing the challenges of searching for new anti-malarial agents, the current study focused on evaluation of anti-malarial activity of root extract of Indigofera spicata.MethodsChloroquine-sensitive rodent malaria parasite, Plasmodium berghei (ANKA strain) was used to infect the Swiss Albino mice in 4-day suppressive and curative models. The crude hydromethanolic root extract of I. spicata at 200, 400 and 600 mg/kg doses was administered to a group of five mice. Important parameters, such as level of parasitaemia, packed cell volume (PCV), survival time, and body weight were determined and the significance of the differences between mean values of the five groups was analysed by one-way ANOVA followed by post hoc Tukey’s Multiple Comparison test.ResultsIn both the suppressive and curative models, 400 and 600 mg/kg doses of the extract suppressed the level of parasitaemia significantly (p < 0.001) compared to the vehicle-treated groups, 34.93 and 53.42%, respectively. However, only the mice which were treated with the 600 mg/kg dose of the extract had significant difference in their mean survival time. In other parameters, namely PCV and mean body weight, there was no statistically significant difference between the extract-treated groups when compared to the negative control.ConclusionsThis study revealed that the root extract of I. spicata possesses anti-malarial activity and necessitates further scientific validation.

Antimalarial evaluation of selected medicinal plant extracts used in Iranian traditional medicine.

Objective(s):In an attempt to discover new natural active extracts against malaria parasites, the present study evaluated the antiplasmodial properties of selected plants based on Iranian traditional medicine.Materials and Methods:Ten plant species found in Iran were selected and collected based on the available literature about the Iranian traditional medicine. The methanolic extracts of these plants were investigated for in vitro antimalarial properties against chloroquine-sensitive (3D7) and multi-drug resistant (K1) strains of Plasmodium falciparum. Their in vivo activity against Plasmodium berghei infection in mice was also determined. Cytotoxicity tests were carried out using the Raji cells line using the MTT assay. The extracts were phytochemically screened for their active constituents.Results:According to the IC50 and selectivity index (SI) values, of the 10 selected plant species, Citrullus colocynthis, Physalis alkekengi, and Solanum nigrum displayed potent in vitro antimalarial activity against both 3D7 and K1 strains with no toxicity (IC50= 2.01-18.67 µg/ml and SI=3.55 to 19.25). Comparisons between treated and untreated control mice showed that the mentioned plant species reduced parasitemia by 65.08%, 57.97%, and 60.68%, respectively. The existence of antiplasmodial compounds was detected in these plant extracts.Conclusion:This was the first study to highlight the in vitro and in vivo antiplasmodial effects of C. colocynthis, P. alkekengi, and S. nigrum in Iran. Future studies can use these findings to design further biological tests to identify the active constituents of the mentioned plant species and clarify their mechanism of action.

Antimalarial, antiplasmodial and analgesic activities of root extract of Alchornea laxiflora

Context: Alchornea laxiflora (Benth.) Pax. & Hoffman (Euphorbiaceae) root decoctions are traditionally used in the treatment of malaria and pain in Nigeria.Objective: To assess the antimalarial, antiplasmodial and analgesic potentials of root extract and fractions against malarial infections and chemically-induced pains.Material and methods: The root extract and fractions of Alchornea laxiflora were investigated for antimalarial activity against Plasmodium berghei infection in mice, antiplasmodial activity against chloroquine sensitive (Pf 3D7) and resistant (Pf INDO) strains of Plasmodium falciparum using SYBR green assay method and analgesic activity against experimentally-induced pain models. Acute toxicity study of the extract, cytotoxic activity against HeLa cells and GCMS analysis of the active fraction were carried out.Results: The root extract (75–225 mg/kg, p.o.) with LD50 of 748.33 mg/kg exerted significant (p < 0.05–0.001) antimalarial activity against P. berghei infection in suppressive, prophylactive and curative tests. The root extract and fractions also exerted moderate activity against chloroquine sensitive (Pf 3D7) and resistant (Pf INDO) strains of P. falciparum with the ethyl acetate fraction exerting the highest activity with IC50 value of 38.44 ± 0.89 μg/mL (Pf 3D7) and 40.17 ± 0.78 μg/mL (Pf INDO). The crude extract was not cytotoxic to HeLa cells with LC50 value >100 μg/mL. The crude extract and ethyl acetate fraction exerted significant (p < 0.05–0.001) analgesic activity in all pain models used.Discussion and conclusions: These results suggest that the root extract/fractions of A. laxiflora possess antimalarial, antiplasmodial and analgesic potentials and these justify its use in ethnomedicine to treat malaria and pain.

In vitro and in vivo anti-malarial activity of novel harmine-analog heat shock protein 90 inhibitors: a possible partner for artemisinin.

BackgroundThe emergence of artemisinin-resistant Plasmodium falciparum strains poses a serious challenge to the control of malaria. This necessitates the development of new anti-malarial drugs. Previous studies have shown that the natural beta-carboline alkaloid harmine is a promising anti-malarial agent targeting the P. falciparum heat-shock protein 90 (PfHsp90). The aim of this study was to test the anti-malarial activity of harmine analogues.MethodsForty-two harmine analogues were synthesized and the binding of these analogues to P. falciparum heat shock protein 90 was investigated. The in vitro anti-malarial activity of two of the analogues, 17A and 21A, was evaluated using a 72-h growth inhibition assay. The in vivo anti-malarial activity was tested in Plasmodium berghei infection of BALB/c mice. The potential of 21A for a combination treatment with artemisinin was evaluated using in vivo combination study with dihydro-artemisinin in BALB/c mice. Cytotoxicity of the harmine analogues was tested in vitro using HepG2 and HeLa cell lines.Results17A and 21A bound to PfHsp90 with average IC50 values of 12.2 ± 2.3 and 23.1 ± 8.8 µM, respectively. They also inhibited the P. falciparum W2 strain with average IC50 values of 4.2 ± 1.3 and 5.7 ± 1.7 µM, respectively. In vivo, three daily injections of P. berghei-infected BALB/c mice with 100 mg/kg of either 17A or 21A showed significant reduction in parasitaemia with a 51.5 and 56.1% reduction, respectively. Mice treated with 17A and 21A showed a median survival time of 11 and 14 days, respectively, while the vehicle control mice survived a median of only 8.5 days. A dose-ranging experiment with 21A showed that the compound has a dose-dependent anti-malarial effect. Furthermore, treatment of infected mice with a combination of 21A and dihydroartemisinin (DHA) showed a dramatic reduction in parasitaemia compared to treatment with DHA alone.ConclusionA novel and non-toxic harmine analogue has been synthesized which binds to PfHsp90 protein, inhibits P. falciparum in vitro at micromolar concentration, reduces parasitaemia and prolongs survival of P. berghei-infected mice with an additive anti-malarial effect when combined with DHA.

Larval diet affects mosquito development and permissiveness to Plasmodium infection.

The larval stages of malaria vector mosquitoes develop in water pools, feeding mostly on microorganisms and environmental detritus. Richness in the nutrient supply to larvae influences the development and metabolism of larvae and adults. Here, we investigated the effects of larval diet on the development, microbiota content and permissiveness to Plasmodium of Anopheles coluzzii. We tested three fish diets often used to rear mosquitoes in the laboratory, including two pelleted diets, Dr. Clarke’s Pool Pellets and Nishikoi Fish Pellets, and one flaked diet, Tetramin Fish-Flakes. Larvae grow and develop faster and produce bigger adults when feeding on both types of pellets compared with flakes. This correlates with a higher microbiota load in pellet-fed larvae, in agreement with the known positive effect of the microbiota on mosquito development. Larval diet also significantly influences the prevalence and intensity of Plasmodium berghei infection in adults, whereby Nishikoi Fish Pellets-fed larvae develop into adults that are highly permissive to parasites and survive longer after infection. This correlates with a lower amount of Enterobacteriaceae in the midgut microbiota. Together, our results shed light on the influence of larval feeding on mosquito development, microbiota and vector competence; they also provide useful data for mosquito rearing.

The evolutionary divergence of STAT transcription factor in different Anopheles species

Anopheles mosquito transmits Plasmodium, the malaria causing parasite. Different species of Anopheles mosquito dominate in a particular geographical location and are capable of transmitting specific strains of Plasmodium. It is important to understand the biology of different anophelines to control the parasite transmission. STAT is an evolutionary conserved transcription factor that regulates the parasite development in African malaria vector Anopheles gambiae. Unlike Drosophila and Aedes aegypti, where a single STAT gene plays an important role in immunity, An. gambiae contains one evolutionary conserved STAT-A and another retro-duplicated, introns-less STAT-B gene. To find out whether other species of Anopheles also have two STATs, the available genomic data of different anophelines were used to annotate their STATs through in silico analyses. Our results revealed that Indian malaria vector An. stephensi genome contains two STATs, AsSTAT-A and AsSTAT-B genes. These genes were cloned and confirmed by sequencing. Both AsSTATs were found to be expressed in different development stages of mosquito. However, the relative mRNA levels of evolutionary conserved AsSTAT-A gene were always higher than the retroduplicated AsSTAT-B gene. STAT pathway was activated upon Plasmodium berghei infection, indicated its role in immunity. Furthermore, comparative in silico analysis of eighteen Anopheles species revealed that five species: An. sinensis, An. albimanus, An. darlingi, An. dirus andAn. farauti do not contain STAT-B gene in their genome. Interestingly, thirteen species of the subgenus Anopheles and Cellia that contain both STATs were also mutually diverged. This consequence leads to sequence variability in some significant protein motifs within the STAT-B genes. Phylogenetic analyses indicated that an independent, lineage-specific duplication occurred in the subgenus Cellia after the diversification of series Neomyzomyia from its last common ancestor. In An. atroparvus (subgenus Anopheles), STAT gene underwent recent lineage-specific duplication and give rise to a highly similar STAT-B gene. This suggested that the genetic divergence in various Anopheles species might appeared due to their adaptations to the altered environmental conditions or pathogen encounters.

Comparing Hydroxychloroquine and Pyrimethamine With Sulfadoxine-Pyrimethamine to Treat Plasmodium berghei Infection in Mice

Background: Malaria is caused by a parasitic protozoan called Plasmodium with an estimated mortality rate of one million people annually and it is estimated that half of the world's population are at risk for this disease. Objectives: The current study aimed to compare the effect of hydroxychloroquine and pyrimethamine with sulfadoxine-pyrimethamine to treat Plasmodium berghei infection in mice. Pyrimethamine, hydroxychloroquine and sulfadoxine-pyrimethamine were used in the current study. Methods: Four groups of mice each including nine mice were selected. The mice were infected by intraperitoneally injection of Plasmodium berghei infected red blood cells. One group was considered as a positive control and three other ones received each one of the drugs. On days 4, 7, 14, 21 and 28, a blood smear was prepared from each mouse, stained with Giemsa and the parasitemia rate was calculated. Results: Parasitemia in the positive control group showed an increase on days four and seven at a level of 5.9% and 23.7%, respectively, which was statistically significant compared with the other groups (P < 0.05). The parasitemia remarkably decreased in the group receiving sulfadoxine-pyrimethamine than in the one taking pyrimethamine (P < 0.05). In addition, the mortality rate in mice treated with sulfadoxine-pyrimethamine was lower than those of the other groups (P < 0.05). The survival time in the group treated with sulfadoxine-pyrimethamine was 28 days on average and in the group treated with pyrimethamine and hydroxychloroquine were 15.56 and 26.44 days, respectively. Conclusions: The results of the article suggested that malaria treatment strategy shifts completely from the monotherapy; therefore, the combination drugs should be used for this purpose, especially in endemic areas.

ICI 56,780 Optimization: Structure-Activity Relationship Studies of 7-(2-Phenoxyethoxy)-4(1H)-quinolones with Antimalarial Activity.

Though malaria mortality rates are down 48% globally since 2000, reported occurrences of resistance against current therapeutics threaten to reverse that progress. Recently, antimalarials that were once considered unsuitable therapeutic agents have been revisited to improve physicochemical properties and efficacy required for selection as a drug candidate. One such compound is 4(1H)-quinolone ICI 56,780, which is known to be a causal prophylactic that also displays blood schizonticidal activity against P. berghei. Rapid induction of parasite resistance, however, stalled its further development. We have completed a full structure-activity relationship study on 4(1H)-quinolones, focusing on the reduction of cross-resistance with atovaquone for activity against the clinical isolates W2 and TM90-C2B, as well as the improvement of microsomal stability. These studies revealed several frontrunner compounds with superb in vivo antimalarial activity. The best compounds were found to be curative with all mice surviving a Plasmodium berghei infection after 30 days.

Novel factors of Anopheles gambiae haemocyte immune response to Plasmodium berghei infection.

BackgroundInsect haemocytes mediate cellular immune responses (e.g., phagocytosis) and contribute to the synthesis of humoral immune factors. In previous work, a genome-wide molecular characterization of Anopheles gambiae circulating haemocytes was followed by functional gene characterization using cell-based RNAi screens. Assays were carried out to investigate the role of selected haemocyte-specific or enriched genes in phagocytosis of bacterial bio-particles, expression of the antimicrobial peptide cecropin1, and basal and induced expression of the mosquito complement factor LRIM1 (leucine-rich repeat immune gene I).FindingsHere we studied the impact of a subset of genes (37 candidates) from the haemocyte-specific dsRNA collection on the development of Plasmodium in the mosquito by in vivo gene silencing. Our screening identifies 10 novel factors with a role in the mosquito response to Plasmodium. Analysis of in vivo screening phenotypes reveals a significant anti-correlation between the prevalence of oocysts and melanised ookinetes.ConclusionsAmong novel immune genes are putative pattern recognition proteins (leucine-rich repeat, fibrinogen-domain and R-type lectins), immune modulation and signalling proteins (LPS-induced tumor necrosis factor alpha factor, LITAF and CLIP proteases), and components of extracellular matrix such as laminin and collagen. Additional identified proteins such as the storage protein hexamerin and vesicular-type ATPase (V-ATPase) are associated for the first time with the mosquito response against Plasmodium.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1359-y) contains supplementary material, which is available to authorized users.

Antimalarial efficacy of low molecular weight chitosan against Plasmodium berghei infection in mice

Antimalarial efficacy of low molecular weight chitosan against Plasmodium berghei infection in mice

Antimalarial and Anti-Hemolytic Properties of Aqueous Crude Extract of Gynostemma pentaphyllum Leaves against Plasmodium berghei Infection in Mice

Continuous emergence of antimalarial drug resistant malaria parasites warrant urgent search for new antimalarials. Traditional medicinal plant extracts have been the main sources for screening antimalarial activity. Accordingly, this study was aimed at investigation the antimalarial and anti-hemolytic properties of aqueous crude extract of Gynostemma pentaphyllum leaves against Plasmodium berghei infected mice. Aqueous crude extract of G. pentaphyllum leaves have been prepared and tested for acute toxicity and antimalarial efficacy in P. berghei ANKA infected mice. At three oral doses of 100, 500 and 1,000 mg/kg of extract were safe, chemosuppressive and thus prevented packed cell volume reduction in a dose-dependent manner compared to the untreated control group. The maximum efficacy was found at the dose of 1,000 mg/kg. This study suggests that the aqueous crude extract of this plant have promising antimalarial activity against P. berghei in a dose-dependent manner, which supports the traditional use of this plant for malaria treatment.

Antipyretic and antimalarial activities of Solenostemon monostachyus

Context: Solenostemon monostachyus P. Beauv (Lamiaceae) is an important herb used traditionally in the treatment of malaria, fever, and other diseases.Objectives: Antiplasmodial and antipyretic activities of S. monostachyus aerial extract were evaluated to ascertain the folkloric claim of its antimalarial and antipyretic activities.Materials and methods: The extract (75–225 mg/kg) and fractions (chloroform and aqueous; 150 mg/kg) of S. monostachyus were investigated for suppressive, prophylactic, and curative antiplasmodial activities against chloroquine-sensitive Plasmodium berghei infections in Swiss albino mice and for antipyretic activity against 2,4-dinitrophenol and yeast-induced pyrexia. Artesunate (5 mg/kg) and pyrimethamine (1.2 mg/kg) were used as positive controls for antiplasmodial models. Thin films made from tail blood of each mouse were used to assess the level of parasitaemia of the mice.Results: The extract/fractions progressively reduced parasitaemia induced by chloroquine sensitive P. berghei infection in prophylactic (28.48–71.72%), suppressive (12.52–72.47%), and curative (22.4–82.34%) models in mice. These reductions were statistically significant (p < 0.01–0.001). They also improved significantly (p < 0.01–0.001) the mean survival time (MST) from 12.26 to 25.63 d relative to control (11.36 d). The activities of extract/fractions were incomparable with that of the standard drugs used (artesunate and pyrimethamine). The extract exerted prominent inhibition of pyrexia on dinitrophenol (87.33–90.11%, 5 h) and yeast (56.22–65.33, 5 h) induced pyrexia. Inhibition was significant (p < 0.05–0.001) from 3 to 5 h post-administration of extract and in a dose-dependent fashion.Conclusion: The plant may possess antiplasmodial and antipyretic effects which may in part be mediated through the chemical constituents of the plant.

Antimalarial activity of 80 % methanolic extract of Brassica nigra (L.) Koch. (Brassicaceae) seeds against Plasmodium berghei infection in mice.

BackgroundResistances to currently available drugs and insecticides, significant drug toxicities and costs and lack of vaccines currently complicated the treatment of malaria. A continued search for safe, effective and affordable plant-based antimalarial agents thus becomes crucial and vital in the face of these difficulties. The aim of the study was to evaluate the antimalarial activity of 80 % methanolic extract of the seeds of Brassica nigra against Plasmodium berghei infection in mice.MethodChloroquine sensitive Plasmodium berghei (ANKA strain) was used to test the antimalarial activity of the extract. In suppressive and prophylactic models, Swiss albino male mice were randomly grouped into five groups of five mice each. Group I mice were treated with the vehicle, group II, III and IV were treated with 100, 200, and 400 mg/kg of the extract, respectively and the last group (V) mice were treated with chloroquine (10 mg/kg). The level of parasitemia, survival time and variation in weight of mice were used to determine the antimalarial activity of the extract.ResultsChemosuppressive activities produced by the extract of the seeds of Brassica nigra were 21.88, 50.00 (P < 0.01) and 53.13 % (P < 0.01), while the chemoprophylactic activities were 17.42, 21.21 and 53.79 % (P < 0.05) at 100, 200 and 400 mg/kg of the extract, respectively as compared to the negative control. Mice treated with 200 and 400 mg/kg extract were significantly (P < 0.05) lived longer and gained weight as compared to negative control in 4-day suppressive test.ConclusionFrom this study, it can be concluded that the seed extract of Brassica nigra showed good chemosuppressive and moderate chemoprophylactic activities and the plant may contain biologically active principles which are relevant in the treatment and prophylaxis of malaria, thus supporting further studies of the plant for its active components.