Effect of selected local medicinal plants on the asexual blood stage of chloroquine resistant Plasmodium falciparum

Cardioprotective Effects of Vitex negundo: A Review of Bioactive Extracts and Compounds

There has been accumulating interest in the application of medicinal plants as alternative medicine to treat various diseases and/or to develop modern medicines. Vitex negundo is one of such medicinal plants that has been of interest to many researchers and has been of use in traditional medicine. V. negundo is found in Sri Lanka, Madagascar, Malaysia, India, China, The Philippines and East Africa. Therapeutic properties of V. negundo have previously been reviewed. Different parts, preparations and bioactive components of V. negundo possess potential protective and therapeutic effects against cardiovascular disease and related conditions as demonstrated in previous studies. We review the present state of scientific knowledge on the potential use of V. negundo and some of its bioactive components in protecting against cardiovascular diseases and related pathologies. Previous studies in animal and non-animal experimental models, although limited in number and vary in design, seem to support the cardioprotective effect of V. negundo and some of its active components. However, there is need for further preclinical and clinical studies to validate the use of V. negundo and its active constituents in protection and treatment of cardiovascular diseases. Additionally, since only a few V. negundo compounds have been evaluated, specific cardioprotective effects or mechanisms and possible side effects of other V. negundo compounds need to be extensively evaluated.

Annona muricata Linn and Khaya grandifoliola C.DC. Reduce Oxidative Stress In Vitro and Ameliorate Plasmodium berghei-Induced Parasitemia and Cytokines in BALB/c Mice

Background.

Annona muricata and Khaya grandifoliola are ethnomedicinally used for the treatment of malaria and have been experimentally shown to have an anti-plasmodial effect, but the mechanisms involved are not fully understood. This study investigated the effect of the ethanol extracts of their leaves on parasitemia, radical scavenging and cytokines in Plasmodium berghei ANKA-infected BALB/c mice.

Methods.

BALB/c mice were infected with P. berghei and treated with chloroquine, A. muricata or K. grandifoliola extract for 4 days. The percentage of parasitemia and the level of cytokine expression were determined after treatment. Trace element, phytochemical and nitric oxide (NO) scavenging activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging properties assays were done to study the antioxidant effects of AN and KG in vitro.

Results.

P. berghei consistently increased parasitemia in BALB/c mice. The tested doses (100-, 200-, and 400 mg/kg) of A. muricata and K. grandifoliola attenuated the P. berghei-induced elevation of parasitemia and cytokines (TNF-α, IL-5, and IL-6) in vivo during the experimental period, though not as much as chloroquine. Moreover, both extracts scavenged the DPPH and NO radicals, though A. muricata had more anti-oxidant effect than K. grandifoliola in-vitro.

Conclusion.

The ethanol extracts of A. muricata and K. grandifoliola reduce parasitemia in P. berghei-treated mice BALB/c by scavenging free radicals and reducing cytokines, though the extracts were not as effective as chloroquine.

In vitro antimalarial activity of Garcinia parvifolia Miq. Stem extracts and fractions on Plasmodium falciparum lactate dehydrogenase (LDH) assay

OBJECTIVES

The rapid spread of antimalarial drug resistance is becoming a problem in the treatment of malaria. The fact was indicated the importance of finding new antimalarial drugs. The genus Garcinia is well known to be a rich source of bioactive prenylated xanthones and triterpenes reported for their antimalarial activity. Garcinia parvifolia is one of the Garcinia genera that can be explored for the search of new antimalarial drugs. This study was aimed to determine the antimalarial activities of G. parvifolia extracts and fractions.

METHODS

Garcinia parvifolia Miq. stem was collected from Balikpapan Botanical Garden in East Kalimantan, Indonesia, was extracted gradually with n-hexane, dichloromethane, and methanol by ultrasonic assisted method. The most active extract was further separated using the open column chromatography method. All extracts and fractions were tested against Plasmodium falciparum 3D7 using lactate dehydrogenase (LDH) assay and followed by IC₅₀ determination.

RESULTS

The results showed that all extracts inhibit P. falciparum growth by LDH assay. The highest inhibition was showed by dichloromethane stem extract (BP12-S-D) with the IC₅₀ value of 6.61 ± 0.09 μg/mL. Further fractionation of BP12-S-D has obtained 10 fractions. All of them were identified by TLC, and a brownish-yellow spot (fraction-1) appears after spraying with 10% H₂SO₄. Fraction-1 (F1) performed the highest parasite growth inhibition with the IC₅₀ value of 6.00 ± 0.03 μg/mL compared with other fractions. This fraction was classified as having a promising activity of antimalarial. The fraction-1 was identified using HPLC, and two major peaks were observed (A and B). The UV-Vis spectra showed the absorption at wavelengths 250 and 278 (A), 243, 281, and 317 nm (B). Based on the profile of TLC, HPLC, and UV-Vis spectra of F1, it was expected that the active compounds are flavonoid (A) and xanthone (B).

CONCLUSIONS

The fraction-1 of dichloromethane extract of G. parvifolia Miq. stem has the highest antimalarial activity. It might be a potential candidate for the new antimalarial drug.

Anti-parasitic activity of Annona muricata L. leaf ethanolic extract and its fractions against Toxoplasma gondii in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Sulfadiazine and pyrimethamine are the two drugs used as part of the standard therapy for toxoplasmosis, however; they may cause adverse side effects and fail to prevent relapse in many patients, rendering infected individuals at risk of reactivation upon becoming immunocompromised. Extracts from various parts of Annona muricata have been widely used medicinally for the management, control and/or treatment of several human diseases, acting against parasites that cause diseases in humans.

AIM OF THE STUDY

This study was performed to investigate the action of the ethanolic extract of A. muricata (EtOHAm) and its fractions in the control of the apicomplexan parasite Toxoplasma gondii in vitro and in vivo, and the effect of EtOHAm on the inflammatory response and lipid profile alteration induced by in vivo T. gondii infection.

MATERIALS AND METHODS

The cytotoxicity of EtOHAm and its fractions ethyl acetate (EtOAcAm), n-butanol (BuOHAm), aqueous (H₂OAm), hexane (HexAm) and dichloromethane (CH₂Cl₂Am) was evaluated in NIH/3T3 fibroblasts using the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The cells were infected with T. gondii, treated with the extracts, and parasite proliferation was analyzed. For the in vivo experiments, C57BL/6 mice were orally infected with T. gondii and, treated with different concentrations of extract fractions that were effective in vitro (EtOHAm, EtOAcAm, HexAm and CH₂Cl₂Am). Tissue parasitism, histological alterations, systemic cytokine and lipid profile were investigated.

RESULTS

EtOHAm, EtOAcAm, BuOHAm, H₂OAm presented low cytotoxicity until doses of 200 μg/mL, while HexAm and CH₂Cl₂Am presented toxicity from doses of 100μg/mL. EtOHAm, HexAm and CH₂Cl₂Am decreased the parasitism in vitro, presenting a therapeutic index of 2.62, 2.44, and 2.96, respectively. In vivo, EtOHAm, HexAm and CH₂Cl₂Am improved the survival rate of infected animals, however, only EtOHAm was able to decrease the parasitism in the small intestine and lung. Additionally, EtOHAm decreased the systemic interferon (IFN)-γ and tumor necrosis factor (TNF) systemically in infected mice, and was able to maintain the triglycerides and very-low-density lipoprotein (VLDL) lipid fractions at similar levels to uninfected animals. Although treatment with EtOHAm could not control the inflammation induced by oral infection in the tissues analyzed, it was able to preserve the number of goblet cells in the small intestine.

CONCLUSIONS

Ethanolic A. muricata leaf extract could be considered as a good candidate for the development of a complementary/alternative therapy against toxoplasmosis, and also as an anti-inflammatory alternative for decreasing TNF and IFN-γ concentrations and lipid fractions in specific diseases.

Taming the Boys for Global Good: Contraceptive Strategy to Stop Malaria Transmission

Transmission of human malaria parasites (Plasmodium spp.) by Anopheles mosquitoes is a continuous process that presents a formidable challenge for effective control of the disease. Infectious gametocytes continue to circulate in humans for up to four weeks after antimalarial drug treatment, permitting prolonged transmission to mosquitoes even after clinical cure. Almost all reported malaria cases are transmitted to humans by mosquitoes, and therefore decreasing the rate of Plasmodium transmission from humans to mosquitoes with novel transmission-blocking remedies would be an important complement to other interventions in reducing malaria incidence.

Terminalia albida treatment improves survival in experimental cerebral malaria through reactive oxygen species scavenging and anti-inflammatory properties

Background

The development of Plasmodium resistance to the last effective anti-malarial drugs necessitates the urgent development of new anti-malarial therapeutic strategies. To this end, plants are an important source of new molecules. The objective of this study was to evaluate the anti-malarial effects of Terminalia albida, a plant used in Guinean traditional medicine, as well as its anti-inflammatory and antioxidant properties, which may be useful in treating cases of severe malaria.

Methods

In vitro antiplasmodial activity was evaluated on a chloroquine-resistant strain of Plasmodium falciparum (K-1). In vivo efficacy of the plant extract was measured in the experimental cerebral malaria model based on Plasmodium berghei (strain ANKA) infection. Mice brains were harvested on Day 7–8 post-infection, and T cells recruitment to the brain, expression levels of pro- and anti-inflammatory markers were measured by flow cytometry, RT-qPCR and ELISA. Non-malarial in vitro models of inflammation and oxidative response were used to confirm Terminalia albida effects. Constituents of Terminalia albida extract were characterized by ultra‐high performance liquid chromatography coupled with high resolution mass spectrometry. Top ranked compounds were putatively identified using plant databases and in silico fragmentation patterns.

Results

In vitro antiplasmodial activity of Terminalia albida was confirmed with an IC50 of 1.5 μg/mL. In vivo, Terminalia albida treatment greatly increased survival rates in P. berghei-infected mice. Treated mice were all alive until Day 12, and the survival rate was 50% on Day 20. Terminalia albida treatment also significantly decreased parasitaemia by 100% on Day 4 and 89% on Day 7 post-infection. In vivo anti-malarial activity was related to anti-inflammatory properties, as Terminalia albida treatment decreased T lymphocyte recruitment and expression of pro-inflammatory markers in brains of treated mice. These properties were confirmed in vitro in the non-malarial model. In vitro, Terminalia albida also demonstrated a remarkable dose-dependent neutralization activity of reactive oxygen species. Twelve compounds were putatively identified in Terminalia albida stem bark. Among them, several molecules already identified may be responsible for the different biological activities observed, especially tannins and triterpenoids.

Conclusion

The traditional use of Terminalia albida in the treatment of malaria was validated through the combination of in vitro and in vivo studies.

Ethanol Extracts from Thai Plants have Anti-Plasmodium and Anti-Toxoplasma Activities In Vitro

PURPOSE

The ethanol extracts from seven Thai plants, Kaempferia parviflora, Stemona tuberosa Lour., Ananas comosus, Punica granatum, Musa sapientum L., Pseuderanthemum palatiferum and Annona muricata L., which are traditionally used in Thailand to support human health, were evaluated for their anti-Plasmodium and anti-Toxoplasma activities, and for their cytotoxicities against human foreskin fibroblasts in vitro.

RESULTS

The K. parviflora, P. palatiferum and A. muricata extracts were active against P. falciparum (3D7) with selectivity index (SI) values > 10, while their half maximal inhibitory concentrations (IC50) were 28.7 µg/ml, 78.8 µg/ml and 46.1 µg/ml, respectively. Extracts from K. parviflora and M. sapientum (ripe fruit peel) inhibited T. gondii (RH) growth with IC50 values of 53.5 µg/ml and 90.4 µg/ml, respectively. The SI values of the extracts from K. parviflora and M. sapientum (ripe fruit peel) were 9.0 and 10.8, respectively.

CONCLUSION

Our data show that some of the aforementioned ethanol extracts are potential sources of new drugs to treat Plasmodium and Toxoplasma infections.

Evaluation of anti-proliferative activity of medicinal plants used in Asian Traditional Medicine to treat cancer

ETHNOPHARMACOLOGICAL RELEVANCE

The extensive biodiversity of plants in Southeast Asia and inadequate research hitherto warrant a continued investigation into medicinal plants. On the basis of a careful review of fresh medicinal plant usage to treat cancer from previous ethnobotanical interviews in Singapore and from the traditional uses of the indigenous plants, fresh leaves of seven locally grown medicinal plant species were evaluated for anti-proliferative activity.

AIM OF THE STUDY

To evaluate the anti-proliferative activity of local medicinal plant species Clausena lansium Skeels, Clinacanthus nutans (Burm. f.) Lindau, Leea indica (Burm. f.) Merr., Pereskia bleo (Kunth) DC., Strobilanthes crispus (L.) Blume, Vernonia amygdalina Delile and Vitex trifolia L.

MATERIALS AND METHOD

Fresh, healthy and mature leaves of the seven medicinal plants were harvested from various locations in Singapore and Malaysia for Soxhlet, ultrasonication and maceration extractions in three different solvents (water, ethanol and methanol). Cell proliferation assay using water soluble tetrazolium salt (WST-1) assay was performed on twelve human cancer cell lines derived from breast (MDA-MB-231, T47D), cervical (C33A), colon (HCT116), leukemia (U937), liver (HepG2, SNU-182, SNU-449), ovarian (OVCAR-5, PA-1, SK-OV-3) and uterine (MES-SA/DX5) cancer.

RESULTS

A total of 37 fresh leaf extracts from seven medicinal plants were evaluated for their anti-tumour activities in twelve human cancer cell lines. Of these, the extracts of C. lansium, L. indica, P. bleo, S. crispus, V. amygdalina and V. trifolia exhibited promising anti-proliferative activity against multiple cancer cell lines. Further investigation of selected promising leaf extracts indicated that maceration methanolic extract of L. indica was most effective overall against majority of the cancer cell lines, with best IC₅₀ values of 31.5 ± 11.4 µg/mL, 37.5 ± 0.7 µg/mL and 43.0 ± 6.2 µg/mL in cervical C33A, liver SNU-449, and ovarian PA-1 cancer cell lines, respectively.

CONCLUSION

The results of this study provide new scientific evidence for the traditional use of local medicinal plant species C. lansium, L . indica, P. bleo, S. crispus, V. amygdalina and V. trifolia in cancer treatment. These results highlight the importance of the upkeep of these indigenous plants in modern society and their relevance as resources for drug discovery.

Anticancer Properties of Graviola (Annona muricata): A Comprehensive Mechanistic Review

Graviola (Annona muricata) is a small deciduous tropical evergreen fruit tree, belonging to the Annonaceae family, and is widely grown and distributed in tropical and subtropical regions around the world. The aerial parts of graviola have several functions: the fruits have been widely used as food confectionaries, while several preparations, especially decoctions of the bark, fruits, leaves, pericarp, seeds, and roots, have been extensively used in traditional medicine to treat multiple ailments including cancers by local communities in tropical Africa and South America. The reported therapeutic benefits of graviola against various human tumors and disease agents in in vitro culture and preclinical animal model systems are typically tested for their ability to specifically target the disease, while exerting little or no effect on normal cell viability. Over 212 phytochemical ingredients have been reported in graviola extracts prepared from different plant parts. The specific bioactive constituents responsible for the major anticancer, antioxidant, anti-inflammatory, antimicrobial, and other health benefits of graviola include different classes of annonaceous acetogenins (metabolites and products of the polyketide pathway), alkaloids, flavonoids, sterols, and others. This review summarizes the current understanding of the anticancer effects of A. muricata and its constituents on diverse cancer types and disease states, as well as efficacy and safety concerns. It also includes discussion of our current understanding of possible mechanisms of action, with the hope of further stimulating the development of improved and affordable therapies for a variety of ailments.

New Silver Complexes with Mixed Thiazolidine and Phosphine Ligands as Highly Potent Antimalarial and Anticancer Agents

Five silver(I) complexes containing a mixed ligand system of phosphine and thiazolidine were successfully synthesized. The structural information of the complexes was assembled using various spectroscopic techniques such as CHN elemental analysis, Fourier transformed infrared (FTIR), 1H, 13C, and 31P{1H} NMR spectroscopy, and thermogravimetric analysis (TGA). A bidentate phosphine ligand acted as a chelating agent which bond to the silver in 1 : 2 molar ratios. Meanwhile, thiazolidine was attached to the silver in a 1 : 1 molar ratio. The antiplasmodial properties of all synthesized complexes were investigated on chloroquine-resistant P. falciparum parasite via HRP2 assays and cytotoxicity tests on Vero cells. Of all the synthesized complexes, complex 2 showed the highest SI value (more than 12.4) followed by complex 5 (6.6). The potent properties of compounds 2 and 5 were also noted in the in vitro antiproliferative assays involving MDA-MB-231 and MCF-7 breast cancer cell lines as well as HT-29 colon cancer cell line. Complex 2 was selective for MDA-MB-231 cells (GI50 = 1.9 ± 0.3 µM), while complex 5 acted predominantly on breast carcinoma cells (GI50 MDA-MB-231 = 4.7 ± 1.1 µM; MCF-7 = 2.9 ± 0.9 µM) instead of colon carcinoma (HT-29) cells (GI50 = 15.1 ± 1.9 µM).

Potent antiplasmodial extracts and fractions from Terminalia mantaly and Terminalia superba

Background

The emergence and spread of malaria parasites resistant to artemisinin-based combination therapy stresses the need for novel drugs against malaria. Investigating plants used in traditional medicine to treat malaria remains a credible option for new anti-malarial drug development. This study was aimed at investigating the antiplasmodial activity and selectivity of extracts and fractions from Terminalia mantaly and Terminalia superba (Combretaceae) that are used in Cameroon to treat malaria.

Methods

Twelve methanolic (m) and water (w) extracts obtained by maceration of powdered dried leaves (l), stem bark (sb) and root (r) of Terminalia mantaly (Tm) and Terminalia superba (Ts) and 12 derived fractions of hexane, chloroform, ethyl acetate and 4 final residues of selected extracts were assessed for antiplasmodial potential in vitro against the chloroquine-resistant PfINDO and the chloroquine-sensitive Pf3D7 strains of Plasmodium falciparum using the SYBR green I-based fluorescence assay. The cytotoxicity of potent extracts and fractions was evaluated in vitro using the MTT assay on HEK239T cell line.

Results

The antiplasmodial IC₅₀ of extracts from both plants ranged from 0.26 to > 25 µg/mL. Apart from the extracts Tmrm and Tsrw that exerted moderate antiplasmodial activities (IC₅₀: 5–20 µg/mL) and Tmrw that was found to be non-active at the tested concentrations (IC₅₀ > 25 µg/mL), all other tested crude extracts exhibited potent activities with IC₅₀ < 5 µg/mL. The aqueous extracts from the stem bark of Terminalia mantaly (Tmsbw) and the leaf of Terminalia superba (Tslw) displayed the highest antiplasmodial activities (IC₅₀: 0.26–1.26 µg/mL) and selectivity (SI > 158) on both resistant PfINDO and sensitive Pf3D7 strains. Four fractions upon further extraction with chloroform and ethyl acetate (TmlwChl, TmsbwChl, TmsbwEA, TsrmEA) afforded from three selected crude extracts (Tmlw, Tmsbw, Tsrm) exhibited highly potent activities against both P. falciparum strains (IC₅₀ < 2 µg/mL) and high selectivity (SI > 109).

Conclusions

The results achieved in this work validate the reported traditional use of Terminalia mantaly and Terminalia superba to treat malaria. Moreover, the highly potent and selective fractions warrant further investigation to characterize the active antiplasmodial principles and progress them to rodent malaria models studies if activity and selectivity are evidenced.

Genotoxicity study of Ethiopian medicinal plant extracts on HepG2 cells

BACKGROUND

Most of herbal medicines are used without any standard safety and toxicological trials although common assumption is that these products are nontoxic. However, this assumption is incorrect and dangerous, so toxicological studies should be done for herbal drugs. Although Pterolobium stellatum, Otostegia integrifolia and Vernonia amygdalina root extracts are frequently used in Ethiopian traditional medicine, there are no evidences of their active toxic compounds. Therefore, we made an effort to assess probable genotoxic effect of these plant extracts on DNA of human hematoma (HepG₂) cells using alkaline comet assay.

METHODS

Genotoxic effects of extracts were evaluated using single cell gel electrophoresis (SCGE) method on HepG₂ cell. Regarding comet data, the average mean tail intensities (TI) from each individual experiment and treatment (usually at least 3 cultures/treatment) were pooled and the average mean TI was used as an indicator of DNA damage and the standard error of mean (SEM) as the measure of variance.

RESULTS

DNA damage in the form of comet tail has been observed for 1 and 0.5 mg/ml P. stellatum chloroform and 80% methanol extracts on HepG₂ cells, respectively. The chloroform extract of P. stellatum showed increased tail DNA percentage in a concentration dependent manner. Comet tail length in the chloroform P. stellatum extract treated cells (1 mg/ml) was significantly higher by 89% (p < 0.05) compared to vehicle treated controls. The rest of test extracts seemed to be without genotoxic effect up to a concentration of 0.5 mg/ml.

CONCLUSIONS

Our findings show that two extracts from one plant evaluated have a genotoxic potential in vitro which calls for a more thorough safety evaluation. Such evaluation should include other end-points of genotoxicity apart from DNA damage, and possibly also pure compounds.

Beneficial effect of Punica granatum peel extract on murine malaria-induced spleen injury

BACKGROUND

Multiple drug-resistant malaria parasites have been widely detected, which has encouraged research studies focused on discovering alternative therapies. Medicinal plants such as pomegranate, Punica granatum, have been proven to exhibit antiprotozoal effects and therefore, we examined its effects on murine malaria-induced splenic injury and oxidative stress in this study.

METHODS

Mice were divided into three groups, a vehicle control and two groups that were infected with 10(6) Plasmodium chabaudi-parasitized red blood cells (RBCs). The third group was gavaged with 100 μL of 300 mg/kg pomegranate peel extract for 6 days. All mice were euthanized on day 6 post-infection.

RESULTS

The results revealed the potential antimalarial, antioxidant, and anti-inflammatory effects of pomegranate. Furthermore, pomegranate peel extracts significantly reduced parasitemia and spleen index of the treated mice compared to the untreated group. Additionally, the spleen histology score supported the findings by showing better amelioration in the pomegranate-treated mice than in the untreated mice. Concomitantly, the spleen capsule thickness showed clear evidence of splenomegaly in the untreated mice, as evidenced by the reduced spleen capsule. However, pomegranate peel extract exhibited a remarkable restorative effect on the spleen capsules of the treated mice. Moreover, the extract significantly reduced the expression levels of the proinflammatory cytokines interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ as well as inducible nitric oxide synthase (iNOS). Moreover, our study showed that pomegranate extract profoundly affected oxidative stress levels by reducing the oxidant molecules, nitric oxide (NO) and malondialdehyde (MDA).

CONCLUSION

This study showed that pomegranate clearly induced antimalarial activity in the host by attenuating inflammatory and oxidative stress responses. Furthermore, pomegranate enhanced the innate immune responses and, therefore, could serve an alternative therapy to control clinical malaria episodes and may protect against malaria infection.

In Vivo Antimalarial Activity of Annona muricata Leaf Extract in Mice Infected with Plasmodium berghei

Malaria is one of the most important infectious diseases in the world. The choice for the treatment is highly limited due to drug resistance. Hence, finding the new compounds to treat malaria is urgently needed. The present study was attempted to evaluate the antimalarial activity of the Annona muricata aqueous leaf extract in Plasmodium berghei infected mice. Aqueous leaf extract of A. muricata was prepared and tested for acute toxicity in mice. For efficacy test in vivo, standard 4-day suppressive test was carried out. ICR mice were inoculated with 10⁷ parasitized erythrocytes of P. berghei ANKA by intraperitoneal injection. The extracts (100, 500, and 1000 mg/kg) were then given orally by gavage once a day for 4 consecutive days. Parasitemia, percentage of inhibition, and packed cell volume were subsequently calculated. Chloroquine (10 mg/kg) was given to infected mice as positive control while untreated control was given only distilled water. It was found that A. muricata aqueous leaf extract at doses of 100, 500, and 1000 mg/kg resulted in dose dependent parasitemia inhibition of 38.03%, 75.25%, and 85.61%, respectively. Survival time was prolonged in infected mice treated with the extract. Moreover, no mortality to mice was observed with this extract up to a dose of 4000 mg/kg. In conclusion, the A. muricata aqueous leaf extract exerted significant antimalarial activity with no toxicity and prolonged survival time. Therefore, this extract might contain potential lead molecule for the development of a new drug for malaria treatment.

In vitro and in vivo anti-malarial activity of plants from the Brazilian Amazon

BACKGROUND

The anti-malarials quinine and artemisinin were isolated from traditionally used plants (Cinchona spp. and Artemisia annua, respectively). The synthetic quinoline anti-malarials (e.g. chloroquine) and semi-synthetic artemisinin derivatives (e.g. artesunate) were developed based on these natural products. Malaria is endemic to the Amazon region where Plasmodium falciparum and Plasmodium vivax drug-resistance is of concern. There is an urgent need for new anti-malarials. Traditionally used Amazonian plants may provide new treatments for drug-resistant P. vivax and P. falciparum. Herein, the in vitro and in vivo antiplasmodial activity and cytotoxicity of medicinal plant extracts were investigated.

METHODS

Sixty-nine extracts from 11 plant species were prepared and screened for in vitro activity against P. falciparum K1 strain and for cytotoxicity against human fibroblasts and two melanoma cell lines. Median inhibitory concentrations (IC50) were established against chloroquine-resistant P. falciparum W2 clone using monoclonal anti-HRPII (histidine-rich protein II) antibodies in an enzyme-linked immunosorbent assay. Extracts were evaluated for toxicity against murine macrophages (IC50) and selectivity indices (SI) were determined. Three extracts were also evaluated orally in Plasmodium berghei-infected mice.

RESULTS

High in vitro antiplasmodial activity (IC50 = 6.4-9.9 µg/mL) was observed for Andropogon leucostachyus aerial part methanol extracts, Croton cajucara red variety leaf chloroform extracts, Miconia nervosa leaf methanol extracts, and Xylopia amazonica leaf chloroform and branch ethanol extracts. Paullinia cupana branch chloroform extracts and Croton cajucara red variety leaf ethanol extracts were toxic to fibroblasts and or melanoma cells. Xylopia amazonica branch ethanol extracts and Zanthoxylum djalma-batistae branch chloroform extracts were toxic to macrophages (IC50 = 6.9 and 24.7 µg/mL, respectively). Andropogon leucostachyus extracts were the most selective (SI >28.2) and the most active in vivo (at doses of 250 mg/kg, 71% suppression of P. berghei parasitaemia versus untreated controls).

CONCLUSIONS

Ethnobotanical or ethnopharmacological reports describe the anti-malarial use of these plants or the antiplasmodial activity of congeneric species. No antiplasmodial activity has been demonstrated previously for the extracts of these plants. Seven plants exhibit in vivo and or in vitro anti-malarial potential. Future work should aim to discover the anti-malarial substances present.

Antimalarial and antioxidant activities of Indigofera oblongifolia on Plasmodium chabaudi-induced spleen tissue injury in mice

Malaria is still one of the most common infectious diseases and leads to various public health problems worldwide. Medicinal plants are promising sources for identifying novel agents with potential antimalarial activity. This study aimed to investigate the antimalarial and the antioxidant activities of Indigofera oblongifolia on Plasmodium chabaudi-induced spleen tissue injury in mice. Mice were divided into five groups. The first group served as a vehicle control; the second, third, fourth, and fifth groups were infected with 1 × 10(6) P. chabaudi-parasitized erythrocytes. Mice of the last three groups were gavaged with 100 μl of I. oblongifolia leave extract (IOLE) at a dose of 100, 200, and 300 mg IOLE/kg, respectively, once daily for 7 days. IOLE was significantly able to lower the percentage of parasitemia. The most effective dose was the 100 mg IOLE/kg, which could reduce the parasitemia from about 38 to 12 %. The infection induced spleen injury. This was evidenced by disorganization of spleen white and red pulps, appearance of hemozoin granules and parasitized erythrocytes. These changes in spleen led to the increased histological score. Also, the infection increased the spleen oxidative damage where the levels of nitrite/nitrate, malondialdehyde, and catalase were significantly altered. All these infection-induced parameters were significantly improved during IOLE treatment. In addition, the mRNA expression of inflammatory cytokines interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha were upregulated after infection with P. chabaudi, whereas IOLE significantly reduced the expression of these genes. Our results indicate that I. oblongifolia leaves extract exhibits a significant antimalarial and antioxidant effects, and protects host spleen tissue from injuries induced by P. chabaudi.

Extracts from Annona Muricata L. and Annona Reticulata L. (Annonaceae) Potently and Selectively Inhibit Plasmodium Falciparum

The aim of this work was to screen extracts from Annona muricata and Annona reticulata in vitro against Plasmodium falciparum. Crude ethanolic extracts, methylene chloride fractions, aqueous fractions, subfractions and isolated compounds (stigmasterol-3-O-β-d-glucopyranoside, lichexanthone, gallic acid and β-sitosterol-3-O-β-d-glucopyranoside) were tested for cytotoxicity on erythrocytes and Human Foreskin Fibroblasts cells and against the W2 strain of P. falciparum in culture. Results indicated that none of the extracts was cytotoxic at concentrations up to 10 µg/mL. Most of the extracts, fractions and subfractions inhibited the growth of P. falciparum with IC₅₀ values ranging from 0.07 to 3.46 µg/mL. The most potent was the subfraction 30 from A. muricata stem bark (IC₅₀ = 0.07 µg/mL) with a selectivity index of ˃ 142. Subfraction 3 from A. muricata root also exhibited very good activity (IC₅₀ = 0.09 µg/mL) with a high selectivity index (SI ˃ 111). Amongst the isolated compounds, only gallic acid showed activity with IC₅₀ of 3.32 µg/mL and SI > 10. These results support traditional claims for A. muricata and A. reticulata in the treatment of malaria. Given their limited cytotoxicity profile, their extracts qualify as promising starting points for antimalarial drug discovery.