Evaluation of the anti-malarial activity of crude extract and solvent fractions of the leaves of Olea europaea (Oleaceae) in mice

Efficacy of Albizia malacophylla (A.Rich.) Walp. (Leguminosae) methanol (80%) leaf extract and solvent fractions against Plasmodium berghei-induced malaria in mice model

ETHNOPHARMACOLOGICAL RELEVANCE

Novel drugs are needed to address the issue of malarial infection resistance; natural items can be a different source of these medications. Albizia malacophylla (A. Rich.) Walp. (Leguminosae) is listed as one of the antimalarial medicinal plants in Ethiopian folk medicine. However, there are no reports regarding the biological activity or phytochemistry of the plant.

AIM OF THE STUDY

Thus, this study aimed to evaluate the A. malacophylla crude extract and solvent fractions' in vivo antimalarial activity utilizing 4-day suppressive, preventative, and curative tests in mice infected with P. berghei.

MATERIALS AND METHODS

The parasite Plasmodium berghei, which causes rodent malaria, was used to infect healthy male Swiss Albino mice, weighing 23-28 g and aged 6-8 weeks. Solvent fractions such as methanol, water, and chloroform were given in addition to an 80% methanolic extract at 100, 200, and 400 mg/kg doses. A Conventional test such as parasitemia, survival time, body weight, temperature, and packed cell capacity were employed to ascertain factors such as the suppressive, curative, and preventive tests.

RESULTS

Every test substance dramatically reduced the number of parasites in every experiment. Crude extract (with the highest percentage suppression of 67.78%) performs better antimalarial effect than the methanol fraction, which is the most efficient solvent fraction with a percentage suppression of 55.74%. With a suppression value of 64.83% parasitemia level, the therapeutic effects of 80% methanolic crude extract were greater than its curative and preventative effects in a four-day suppressive test. The survival period (17 days) was longer with the hydroalcoholic crude extract dose of 400 mg/kg than with other doses of the materials under investigation.

CONCLUSIONS

The results of this investigation validate the antimalarial characteristics of A. malacophylla leaf extract. The crude extract prevented weight loss, a decline in temperature, and a reduction in PCV. The results demonstrate that the plant has a promising antimalarial effect against P. berghei, hence supporting the traditional use of the plant. Therefore, it could serve as a foundation for the development of new antimalarial drugs.

In-Vivo Anti-Malarial Activity of 80% Methanol Leaf Extract of Croton Dichogamus Pax and Ehretia Cymosa Thonn in Plasmodium Berghei Infected Mice

Background

Malaria is causing high mortality and morbidity due to Plasmodium's resistance to currently available anti-malarial drugs and mosquito's resistance to insecticides. Thus, there is a critical need to search for novel anti-malarial drugs from natural sources. Therefore, this study investigated in vivo antimalarial activities of two Ethiopian medicinal plants, Croton dichogamus Pax and Ehretia cymosa Thonn, in Plasmodium berghei infected Swiss albino mice.

Methods

Soxhlet extraction method using 80% methanol as a solvent was used to prepare crude extracts of the two plants. Acute oral toxicity and 4-day suppressive in vivo antimalarial activity tests were performed on healthy female mice and P. berghei infected male mice, respectively. Antimalarial activity of the crude extracts at doses of 100, 200, and 400 mg/kg and the standard drug, chloroquine were used to assesse in Plasmodium berghei infected Swiss albino mice. Parasitemia level, packed cell volume, body weight, and rectal temperature of the mice were determined before infection (day 0) and after treatment (day 4). Survival time was determined by recording the date on which the mice died, considering the date of infection as day 0. The recorded data were analyzed using ANOVA and SPSS version 24.

Results

The result of the acute toxicity study revealed that the crude extracts were non-toxic at doses up to 2 g/kg. The extract of E. cymosa suppressed parasitemia level by 66.28, 63.44 and 63.14% at 400, 200, and 100mg/kg, levels while C. dichogamus extract suppressed parasitemia level by 45.29% at a dose of 400mg/kg. The remaining two dose levels of C.dichogamus extract suppressed parasitemia level by < 30%.

Conclusion

C. dichogamus and E. cymosa showed anti-plasmodial activities. E. cymosa exhibited a more pronounced anti-plasmodial effect than C. dichogamus. The activities of both plants observed in this study support their traditional use as antimalarial drugs. Further studies on these plants using solvent fractions are required to identify their active ingredients.

Oleuropein activates autophagy to circumvent anti-plasmodial defense

Antimalarial drug resistance and unavailability of effective vaccine warrant for newer drugs and drug targets. Hence, anti-inflammatory activity of phyto-compound (oleuropein; OLP) was determined in antigen (LPS)-stimulated human THP-1 macrophages (macrophage model of inflammation; MMI). Reduction in the inflammation was controlled by the PI3K-Akt1 signaling to establish the "immune-homeostasis." Also, OLP treatment influenced the cell death/autophagy axis leading to the modulated inflammation for extended cell survival. The findings with MII prompted us to detect the antimalarial activity of OLP in the wild type (3D7), D10-expressing GFP-Atg18 parasite, and chloroquine-resistant (Dd2) parasite. OLP did not show the parasite inhibition in the routine in vitro culture of P. falciparum whereas OLP increased the antimalarial activity of artesunate. The molecular docking of autophagy-related proteins, investigations with MMI, and parasite inhibition assays indicated that the host activated the autophagy to survive OLP pressure. The challenge model of P. berghei infection showed to induce autophagy for circumventing anti-plasmodial defenses.

Prophylactic effects of probiotic bacterium Latilactobacillus sakei on haematological parameters and cytokine profile of mice infected with Plasmodium berghei ANKA during early malaria infection

Malaria is a deadly parasitic disease caused a by protozoan parasite of the genus plasmodium. The challenges facing by chemotherapy and vector control couple with the lack of vaccine against malaria necessitate an urgent need for the development of alternative treatment regimens to combat this disease. One possible antimalarial treatment regimen is the use of probiotic bacteria as dietary supplements. Traditionally fermented milk is a rich source of probiotic bacteria that up to date, very few studies have been carried out on their immunoprotective effects against early malaria infection in mice. This study sought to assess the prophylactic activities of a probiotic bacterium Latilactobacillus sakei on malaria and inflammation in Plasmodium berghei infected mice. The probiotic bacterium was isolated from the Fulani's traditionally fermented milk and identified using the sequencing of the 16S r RNA gene. The repository activity of L. sakei on malaria was assessed using the method described by Peters with slight modification. Eighty-four BALB/c mice were randomly divided into two sets of seven groups of six mice each. One set received orally different doses of L. sakei Chloroquine and Sulfadoxine/Pyrimethamine for seven days before infection while the other set received for fourteen days before infection with 0.1 mL of 107Plasmodium berghei. Parasitaemia density, haematological parameters and inflammatory cytokines profile were evaluated. Data were presented as Mean ± SEM and analysed using SPSS version 20.0. The results of this study revealed that L. sakei significantly (p < 0.05) reduced in dose dependent manner parasite load, body weight loss and reduction of body temperature in all the treated mice when compare to untreated mice. Leukocytopenia, thrombocytosis and inflammation were also found to be significantly (p < 0.05) prevented in treated mice as compared to untreated mice. This study suggested that L sakei possesses immunomodulation and protective effects on early malaria infection in Plasmodium berghei mice.

Ameliorative Effect of Olea europaea Leaf Extract on Cisplatin-Induced Nephrotoxicity in the Rat Model

Background

Olea europaea leaf extract (OELE) has potential health benefits and protects against cytotoxicity. This study investigated the possible ameliorative effect of OELE on cisplatin-induced nephrotoxicity in rats.

Methods

Rats were assigned into six groups; two groups received 150 mg/kg or 300 mg/kg of OELE, one group received a single dose of cisplatin (6 mg/kg) IP on the first day of the experiment, two groups received a single dose of cisplatin 150 mg/kg or 300 mg/kg of OELE on the first day then starting from the fifth day for 10 consecutive days, and one group acted as a control. Results and Conclusion. The findings showed that cisplatin-induced nephrotoxicity was evidenced by a significant increase in serum creatinine blood urea nitrogen (BUN) and a significant decrease in estimated creatinine clearance and potassium level, which corresponded with the alterations in the histopathology of the renal tissue. OELE significantly ameliorated the nephrotoxic effects of cisplatin as dose-dependent.

In vitro anti-plasmodial activity of three selected medicinal plants that are used in local traditional medicine in Amhara region of Ethiopia

BACKGROUND

The plants Aloe weloensis, Lepidium sativum, and Lobelia gibberoa have been used in Ethiopian folklore medicine to treat various diseases including malaria.

METHOD

The in vitro anti-plasmodial activity of the three crude extracts was evaluated using parasite lactate dehydrogenase assay against the chloroquine (CQ)-sensitive D10 and the chloroquine (CQ)-resistant W2 strains.

RESULT

The methanolic extract of L. gibberoa roots showed the highest in vitro anti-plasmodial effect against both D10 and W2 Plasmodium falciparum strains with IC₅₀ value of 103.83 ± 26.17 µg/mL and 47.11 ± 12.46 µg/mL, respectively. However, the methanolic extract of L. sativum seeds and the leaf latex of A. weloensis were not active with an IC₅₀ value > 200 µg/mL against both D10 and W2 strains.

CONCLUSION

The methanolic extract of L. gibberoa roots showed a promising in vitro anti-plasmodial activity against the CQ-sensitive (D10) and CQ-resistant (W2) strains of P. falciparum. Thus, the anti-plasmodial activity of this plant partly justifies and may also support the traditional use against malaria. However, the methanolic extract of L. sativum seeds and the leaf latex of A. weloensis did not exert suppressive activity on the growth of P. falciparum strains.

Evaluation of the Anti-Malarial Activity of the Crude Root Extract and Solvent Fraction of Sesamum indicum (Fabaceae)

Background

A major cumbersome factor in malaria control measure is the new coming antimalarial drug resistance strains. The increase of resistance to the available marketed antimalarial agents dictates the scientific community to search new alternative antimalarial agent from traditional plants. Therefore, our study assesses the antimalarial activity of the crude root extract and solvent fraction of Sesamum indicum in mice.

Methods

The roots of Sesamum indicum were extracted by 80% methanol and fractionated using three solvents with different polarities. The in vivo antimalarial activity was assessed at 200 mg/kg, 400 mg/kg, and 600 mg/kg of the root crude extract and solvent fraction using the 4-day suppressive test. Similarly, the n- butanol fraction extract, which showed better suppression potential in 4-day suppressive test from other fractions was also evaluated in the curative model to assess its curative potential. The % parasitemia suppression, mean survival time, body weight change, rectal temperature change, and packed cell volume change were also evaluated in both models.

Results

Our finding revealed that the crude extract and solvent fraction treated groups had a statistical significant parasitemia suppression and mean survival time improvement as compared to the negative control (p<0.001) in both models in a dose-dependent fashion. The higher dose n-butanol fraction treated group (600mg/kg) showed the highest suppression effect and mean survival time prolongation in both tests from the other two fractions. However, the lowest suppressive effect was observed in 200 mg/kg aqueous fraction extract-treated groups in the 4-day suppressive test.

Conclusion

The crude root extract and solvent fractions of Sesamum indicum possessed a dose dependent antimalarial activity and a significant change in other parameters in both models that strengthen the traditional claim.

Molecular Mechanisms of the Protective Effects of Olive Leaf Polyphenols against Alzheimer's Disease

Alzheimer's Disease (AD) is the cause of around 60-70% of global cases of dementia and approximately 50 million people have been reported to suffer this disease worldwide. The leaves of olive trees (Olea europaea) are the most abundant by-products of the olive grove industry. These by-products have been highlighted due to the wide variety of bioactive compounds such as oleuropein (OLE) and hydroxytyrosol (HT) with demonstrated medicinal properties to fight AD. In particular, the olive leaf (OL), OLE, and HT reduced not only amyloid-β formation but also neurofibrillary tangles formation through amyloid protein precursor processing modulation. Although the isolated olive phytochemicals exerted lower cholinesterase inhibitory activity, OL demonstrated high inhibitory activity in the cholinergic tests evaluated. The mechanisms underlying these protective effects may be associated with decreased neuroinflammation and oxidative stress via NF-κB and Nrf2 modulation, respectively. Despite the limited research, evidence indicates that OL consumption promotes autophagy and restores loss of proteostasis, which was reflected in lower toxic protein aggregation in AD models. Therefore, olive phytochemicals may be a promising tool as an adjuvant in the treatment of AD.

Antimalarial efficacy and toxicological assessment of medicinal plant ingredients of Prabchompoothaweep remedy as a candidate for antimalarial drug development

BACKGROUND

Drug resistance exists in almost all antimalarial drugs currently in use, leading to an urgent need to identify new antimalarial drugs. Medicinal plant use is an alternative approach to antimalarial chemotherapy. This study aimed to explore potent medicinal plants from Prabchompoothaweep remedy for antimalarial drug development.

METHODS

Forty-eight crude extracts from Prabchompoothaweep remedy and its 23 plants ingredients were investigated in vitro for antimalarial properties using Plasmodium lactate dehydrogenase (pLDH) enzyme against Plasmodium falciparum K1 strain and toxicity effects were evaluated in Vero cells. The plant with promising antimalarial activity was further investigated using gas chromatography-mass spectrometry (GC-MS) to identify phytochemicals. Antimalarial activity in mice was evaluated using a four-day suppressive test against Plasmodium berghei ANKA at dose of 200, 400, and 600 mg/kg body weight, and acute toxicity was analyzed.

RESULTS

Of the 48 crude extracts, 13 (27.08%) showed high antimalarial activity against the K1 strain of P. falciparum (IC₅₀ <  10 μg/ml) and 9 extracts (18.75%) were moderately active (IC₅₀ = 11-50 μg/ml). Additionally, the ethanolic extract of Prabchompoothaweep remedy showed moderate antimalarial activity against the K1 strain of P. falciparum (IC₅₀ = 14.13 μg/ml). Based on in vitro antimalarial and toxicity results, antimalarial activity of the aqueous fruit extract of Terminalia arjuna (IC₅₀ = 4.05 μg/ml and CC₅₀ = 219.6 μg/ml) was further studied in mice. GC-MS analysis of T. arjuna extract identified 22 compounds. The most abundant compounds were pyrogallol, gallic acid, shikimic acid, oleamide, 5-hydroxymethylfurfural, 1,1-diethoxy-ethane, quinic acid, and furfural. Analysis of the four-day suppressive test indicated that T. arjuna extract at dose of 200, 400, and 600 mg/kg body weight significantly suppressed the Plasmodium parasites by 28.33, 45.77, and 67.95%, respectively. In the acute toxicity study, T. arjuna extract was non-toxic at 2000 mg/kg body weight.

CONCLUSIONS

The aqueous fruit extract of T. arjuna exerts antimalarial activity against Plasmodium parasites found in humans (P. falciparum K1) and mice (P. berghei ANKA). Acute toxicity studies showed that T. arjuna extract did not show any lethality or adverse effects up to a dose of 2000 mg/kg.

Phytochemical, Antimalarial, and Acute Oral Toxicity Properties of Selected Crude Extracts of Prabchompoothaweep Remedy in Plasmodium berghei-Infected Mice

Malaria remains a life-threatening health problem and encounters with the increasing of antimalarial drug resistance. Medicinal plants play a critical role in synthesizing novel and potent antimalarial agents. This study aimed to investigate the phytochemical constituents, antiplasmodial activity, and evaluate the toxicity of crude ethanolic extracts of Myristica fragrans, Atractylodes lancea, and Prabchompoothaweep remedy in a mouse model. The phytochemical constituents were characterized by liquid chromatography-mass spectrometry (LC-MS). Antimalarial efficacy against Plasmodium berghei was assessed using 4-day suppressive tests at doses of 200, 400, and 600 mg/kg body weight. Acute toxicity was assessed at a dose of 2000 mg/kg body weight of crude extracts. The 4-day suppression test showed that all crude extracts significantly suppressed parasitemia (p < 0.05) compared to the control group. Higher parasitemia suppression was observed both in Prabchompoothaweep remedy at a dose of 600 mg/kg (60.1%), and A. lancea at a dose of 400 mg/kg (60.1%). The acute oral toxicity test indicated that the LD50 values of all extracts were greater than 2000 mg/kg and that these extracts were not toxic in the mouse model. LC-MS analysis revealed several compounds in M. fragrans, A. lancea, and Prabchompoothaweep remedy. For quantitative analysis, 1,2,6,8-tetrahydroxy-3-methylanthraquinone 2-O-b-D-glucoside, chlorogenic acid, and 3-O-(beta-D-glucopyranosyl-(1->6)-beta-D-glucopyranosyl) ethyl 3-hydroxyoctanoate were found in A. lancea, while (7′x,8′x)-4,7′-epoxy-3,8′-bilign-7-ene-3,5′-dimethoxy-4′,9,9′-triol, edulisin III, and tetra-hydrosappanone A trimethyl ether are found in M. fragrans. 6′-O-Formylmarmin was present in the Prabchompoothaweep remedy, followed by pterostilbene glycinate and amlaic acid. This study showed that the ethanolic extracts of A. lancea and Prabchompoothaweep remedy possess antimalarial activity against Plasmodium berghei. None of the extracts had toxic effects on liver and kidney function. Therefore, the ethanolic extract of A. lancea rhizome and Prabchompoothaweep remedy could be used as an alternative source of new antimalarial agents. Further studies are needed to determine the active compounds in both extracts.

Antimalarial Activity of Extract and Fractions of Sauropus androgynus (L.) Merr

Sauropus androgynus (L.) Merr., in the Indonesian local name known as "Katuk," is a tropical shrub plant of the family Euphorbiaceae. Based on genus and chemotaxonomic approaches, as well as in vitro testing of Plasmodium falciparum, leaves of S. androgynus are presumed to have an active compound content as an antimalarial. The current study aims to investigate the antimalarial activity of 96% ethanol extract and fractions of S. androgynus leaves. The ethanolic extract was fractionated using the vacuum liquid chromatography (VLC) method with three solvents of different polarities (n-hexane, chloroform, and 96% ethanol). The fraction obtained was then evaluated for antimalarial activity against P. falciparum 3D7 strain. The ethanolic extract was evaluated for antimalarial suppressive and prophylactic activity against P. berghei-infected mice, as well as inhibitory activity against the heme detoxification process in vitro. Fractionation of ethanolic extract resulted in seven combined fractions, with the most active fraction being FV (50% inhibitory concentration (IC₅₀) = 2.042 µg/mL). The ethanolic extract showed good parasitic suppressive (therapeutic) activity with a median effective dose (ED₅₀) value of 15.35 mg/kg body weight. In a prophylactic test, ethanolic extract showed parasite growth inhibitory activity of 67.74 ± 9.21% after the administration of 400 mg/kg body weight for 4 days before infection, and 65.30 ± 10.44% after the administration of 200 mg/kg body weight for 8 consecutive days (4 days before and after infection). The ethanolic extract also showed an effect in inhibiting the formation of β-hematin of about 26.87-79.36% at a concentration of 0.1-4 mg/mL and an IC₅₀ value of 0.479 mg/mL. The S. androgynus leaves were shown to have antimalarial activity in vitro and in vivo, where ethanolic extract were more active compared with the fraction obtained. The antimalarial properties of the extract showed a higher suppressive activity than prophylactic activity.

Natural Antioxidants as Additional Weapons in the Fight against Malarial Parasite

BACKGROUND

All currently available antimalarial drugs are developed from natural product lineages that may be traced back to herbal medicines, including quinine, lapachol, and artemisinin. Natural products that primarily target free radicals or reactive oxygen species, play an important role in treating malaria.

OBJECTIVES

This review analyses the role of antioxidative therapy in treating malaria by scavenging or countering free radicals and reviews the importance of natural plant extracts as antioxidants in oxidative therapy of malaria treatment.

METHODS

The search for natural antioxidants was conducted using the following databases: ResearchGate, ScienceDirect, Google Scholar, and Bentham Science with the keywords malaria, reactive oxygen species, natural antioxidants, and antiplasmodial.

CONCLUSION

This study reviewed various literature sources related to natural products employed in antimalarial therapy directly or indirectly by countering/scavenging reactive oxygen species published between 2016 till date. The literature survey made it possible to summarize the natural products used in treating malaria, emphasizing botanical extracts as a single component and in association with other botanical extracts. Natural antioxidants like polyphenols, flavonoids, and alkaloids, have a broad range of biological effects against malaria. This review is pivoted around natural antioxidants obtained from food and medicinal plants and explores their application in restraining reactive oxygen species (ROS). We anticipate this article will provide information for future research on the role of antioxidant therapy in malaria infection.

Antimalarial activity of solvent fractions of a leaf of Eucalyptus globulus labill against Plasmodium berghei infected mice

Introduction

The leaf of Eucalyptus globulus is commonly used in the traditional management of malaria. However, the efficacy of solvent fractions are didn’t study yet scientifically. Thus, this study aimed to investigate the antimalarial efficacy of the solvent fractions of the leaf of Eucalyptus globulus in mice against P.berghei.

Methods

The antimalarial activity of the fractions was tested in a 4-day suppressive test, Rane’s test, and prophylactic test models within P.berghei infected mice. The results were analyzed using a one-way analysis of variance (ANOVA) followed by a post hoc Tukey’s test in version 20 SPSS.

Results

All fractions at all test doses in the three test models suppressed parasitemia (p < 0.001) compared to the negative controls. In addition, the CF and EA at all three test doses and the AF at 400 mg/kg in three antimalarial test models showed 50% and above parasitemia suppression. In compliance with this, all fractions at all test doses in all test models prolonged the mean survival time of the mice greater than 12 days, except the AF at a lower dose. All fractions at 400 mg/kg in the three test models prevented (p < 0.001) loss of body weight and rectal temperature compared to the negative controls. Furthermore, all fractions in all test models and doses prevented packed cell volume reduction (p < 0.05 to p < 0.001) compared to the negative controls..

Conclusion

The findings of this study showed that CF and EAF had greater antimalarial activity compared to AF. This could be attributed to the presence of few phytochemicals in the AF in contrast to the CF and EAF. Overall, the results of this study further support the in vitro antimalarial activity study and the traditional use of the leaf in the management of malaria.

In Vivo Anti-Malarial Activity of the Aqueous Root Extract of Euclea divinorum Hiern (Ebenaceae) against Plasmodium berghei ANKA

Background

Drug resistance is a universal challenge to malaria control measures. As a result, the development and discovery of new chemotherapeutic agents from medicinal plants having anti-malarial traditional claims are very important. This work, therefore, attempted to evaluate the anti-malarial activity of the aqueous root extract of E. divinorum using a rodent model of malaria.

Methods

The roots of E. divinorum were extracted by hot decoction using distilled water. Anti-malarial activity of various doses (100 mg/kg, 200 mg/kg, and 600 mg/kg) of the root aqueous extract was evaluated using the 4-day suppressive test as well as curative and repository tests. Parasitemia, rectal temperature, body weight, PCV, and MST were also determined.

Results

The finding showed that there were a dose-related significant parasitemia chemo-suppression and increment in survival time as compared to the negative control (p < 0.001) in all tests. The chemo-suppression effect was higher at 400 mg/kg extract-treated groups in the 4-day suppressive test followed by the curative test. The lowest chemo-prophylaxis effect was observed in 100 mg/kg extract-treated groups in the repository test. Regarding the other parameters, the extract prevented weight loss, temperature drop, and hemolysis in all models but not in a consistent manner.

Conclusion

The current study showed that the aqueous root extract of E. divinorum possessed a varying degree of anti-malarial activity in all three tests, with greater parasitemia suppression observed in the 4-day suppressive test. The extract produced higher parasitemia chemo-suppression and longer survival time in early infections followed by established and then residual infection.

Evaluation of the antimalarial activity and toxicity of Mahanil-Tang-Thong formulation and its plant ingredients

Background

Novel potent antimalarial agents are urgently needed to overcome the problem of drug-resistant malaria. Herbal treatments are of interest because plants are the source of many pharmaceutical compounds. The Mahanil-Tang-Thong formulation is a Thai herbal formulation in the national list of essential medicines and is used for the treatment of fever. Therefore, this study aimed to evaluate the antimalarial activity of medicinal plants in the Mahanil-Tang-Thong formulation.

Methods

Nine medicinal plant ingredients of the Mahanil-Tang-Thong formulation were used in this study. Aqueous and ethanolic extracts of all the plants were analyzed for their phytochemical constituents. All the extracts were used to investigate the in vitro antimalarial activity against Plasmodium falciparum K1 (chloroquine-resistant strain) by using the lactate dehydrogenase (pLDH) method and cytotoxicity in Vero cells by using the 3-(4,5-dimethylthiazol2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Additionally, an extract with potent in vitro antimalarial activity and no toxicity was selected to determine the in vivo antimalarial activity with Peters’ 4-day suppressive test against the Plasmodium berghei ANKA strain. Acute toxicity was evaluated in mice for 14 days after the administration of a single oral dose of 2000 mg/kg.

Results

This study revealed that ethanolic extracts of Sapindus rarak DC., Tectona grandis L.f., Myristica fragrans Houtt. and Dracaena loureiri Gagnep. exhibited potent antimalarial activity, with half-maximal inhibitory concentration (IC50) values of 2.46, 3.21, 8.87 and 10.47 μg/ml, respectively, while the ethanolic of the formulation exhibited moderate activity with an IC50 value of 37.63 μg/ml and its aqueous extract had no activity (IC50 = 100.49 μg/ml). According to the in vitro study, the ethanolic wood extract of M. fragrans was selected for further investigation in an in vivo mouse model. M. fragrans extract at doses of 200, 400, and 600 mg/kg body weight produced a dose-dependent reduction in parasitemia by 8.59, 31.00, and 52.58%, respectively. No toxic effects were observed at a single oral dose of 2000 mg/kg body weight.

Conclusion

This study demonstrates that M. fragrans is a potential candidate for the development of antimalarial agents.

In Vivo Antimalarial Activity of Leaf Extracts and a Major Compound Isolated from Ranunculus multifidus Forsk

The leaves of Ranunculus multifidus Forsk. are traditionally used for the treatment of malaria in several African countries. In the present study, 80% methanol (RM-M) and hydrodistilled (RM-H) extracts of fresh leaves from R. multifidus and its major constituent anemonin were tested for their in vivo antimalarial activity against Plasmodium berghei in mice. Anemonin was also tested for its in vitro antimycobacterial activity against Mycobacterium smegmatis and M. abscessus in a microbroth dilution assay, and bacterial growth was analyzed by OD measurement. The isolation of anemonin from RM-H was carried out using preparative thin layer chromatography (PTLC). The chemical structures of anemonin and its hydrolysis product were elucidated using spectroscopic methods (HR–MS; 1D and 2D-NMR). Results of the study revealed that both RM-M and RM-H were active against P. berghei in mice, although the latter demonstrated superior activity (p < 0.001), as compared to the former. At a dose of 35.00 mg/kg/day, RM-H demonstrated a chemosuppression value of 70% in a 4-day suppressive test. In a 4-day suppressive, Rane’s and prophylactic antimalarial tests, anemonin showed median effective doses (ED₅₀s) of 2.17, 2.78 and 2.70 μM, respectively. However, anemonin did not inhibit the growth of M. smegmatis and M. abscessus.

Studies on Activities and Chemical Characterization of Medicinal Plants in Search for New Antimalarials: A Ten Year Review on Ethnopharmacology

Malaria is an endemic disease that affected 229 million people and caused 409 thousand deaths, in 2019. Disease control is based on early diagnosis and specific treatment with antimalarial drugs since no effective vaccines are commercially available to prevent the disease. Drug chemotherapy has a strong historical link to the use of traditional plant infusions and other natural products in various cultures. The research based on such knowledge has yielded two drugs in medicine: the alkaloid quinine from Cinchona species, native in the Amazon highland rain forest in South America, and artemisinin from Artemisia annua, a species from the millenary Chinese medicine. The artemisinin-based combination therapies (ACTs), proven to be highly effective against malaria parasites, and considered as “the last bullet to fight drug-resistant malaria parasites,” have limited use now due to the emergence of multidrug resistance. In addition, the limited number of therapeutic options makes urgent the development of new antimalarial drugs. This review focuses on the antimalarial activities of 90 plant species obtained from a search using Pubmed database with keywords “antimalarials,” “plants” and “natural products.” We selected only papers published in the last 10 years (2011–2020), with a further analysis of those which were tested experimentally in malaria infected mice. Most plant species studied were from the African continent, followed by Asia and South America; their antimalarial activities were evaluated against asexual blood parasites, and only one species was evaluated for transmission blocking activity. Only a few compounds isolated from these plants were active and had their mechanisms of action delineated, thereby limiting the contribution of these medicinal plants as sources of novel antimalarial pharmacophores, which are highly necessary for the development of effective drugs. Nevertheless, the search for bioactive compounds remains as a promising strategy for the development of new antimalarials and the validation of traditional treatments against malaria. One species native in South America, Ampelozyzyphus amazonicus, and is largely used against human malaria in Brazil has a prophylactic effect, interfering with the viability of sporozoites in in vitro and in vivo experiments.

Evaluation of the Antimalarial Activity of Crude Extract of Eucalyptus globulus Labill. Leaf against Plasmodium berghei in Mice

Introduction

Traditional medicinal plants are used as a common source of developing new and effective antimalarial drugs. E. globulus leaf has been used in the traditional management of malaria in different countries, including Ethiopia. However, there is no in vivo study done on the antimalarial activity of the plant. Thus, this study aimed to evaluate the antimalarial activity of crude extract of E. globulus Labill. leaf in P. berghei-infected mice.

Method

The fresh leaves of E. globulus were collected, washed, air-dried, and made as coarse powder. Either sex of mice aged 6 to 8 weeks was used in the experiment. The antimalarial activity of the crude extract was tested in four-day suppressive, curative (Rane's), and prophylactic (repository) tests. The parameters like level of parasitemia, packed cell volume, body weight, rectal temperature, and mean survival time were recorded. The analysis of the data was done with SPSS version 20 with a 95% confidence interval in one-way ANOVA followed by Tukey's post hoc test.

Results

In all three antimalarial test models, the extract of leaf of E. globulus at all three doses suppressed the level of parasitemia significantly (p < 0.001), increased survival time (p < 0.05 to p < 0.001), and prevented a decrease in body weight as compared to the negative control. The middle and large doses of the extract also decreased loss of body temperature (p < 0.05 to p < 0.001) compared to the negative control. Reduction of packed cell volume was prevented within the three test doses of the extract in both curative and prophylactic tests and middle and large doses in the 4-day suppressive test compared to the negative control.

Conclusion

The crude extract of the plant showed promising antimalarial activity. This supports the traditional use and the in vitro test result of the plant.

In Vitro and In Vivo Antimalarial Activities and Toxicological Assessment of Pogostemon Cablin (Blanco) Benth

The aim of this study was to investigate the antimalarial activities and toxicity of Pogostemon cablin extracts. In vitro activities against the chloroquine-resistant Plasmodium falciparum K1 strain were assessed by using the Plasmodium lactate dehydrogenase enzyme (pLDH) assay, while in vivo activity against the Plasmodium berghei ANKA strain in mice was investigated using a 4-day suppressive test. The in vitro and in vivo toxicity were determined in Vero cells and mice, respectively. The ethanolic extract possessed antimalarial activity with an IC₅₀ of 24.49 ± 0.01 µg/ml, whereas the aqueous extract showed an IC₅₀ of 549.30 ± 0.07 µg/ml. Cytotoxic analyses of the ethanolic and aqueous extracts revealed a nontoxic effect on Vero cells at a concentration of 80 µg/ml. Based on a preliminary study of in vitro antimalarial activity, the ethanolic extract was chosen as a potential agent for further in vivo antimalarial activity analysis in mice. The ethanolic extract, which showed no toxic effect on mice at a dose of 2000 mg/kg body weight, significantly suppressed parasitemia in mice by 38.41%, 45.12% and 89.00% at doses of 200, 400 and 600 mg/kg body weight, respectively. In conclusion, this study shows that the ethanolic P. cablin extract possesses in vitro and in vivo antimalarial activity without toxic effects.

Evaluation of the Antimalarial Activity of the Leaf Latex of Aloe weloensis (Aloaceae) against Plasmodium Parasites

Background

The lack of available vaccines and the emerging resistance to antimalarial drugs have provided the necessity to find noble antimalarial plant-based medicines. The leaf latex Aloe weloensis has been used in folk medicine against malarial and other human ailments in Ethiopia. Hence, the present study aimed to investigate the antimalarial activity of the leaf latex of A. weloensis against Plasmodium parasites.

Materials and Methods

The prophylactic and curative models were employed to determine the in vivo antimalarial activity of the leaf latex A. weloensis against P. berghei infected mice, and the antioxidant activity of the latex was assessed using diphenyl-1-picrylhydrazine (DPPH) assay. Female mice were recruited for toxicity study, and the leaf latex was administered to fasted mice at a dose of 5000 mg/kg. The mice were kept under continuous observation for fourteen days for any signs of overt toxicity.

Results

The leaf latex of A. weloensis was safe up to 5000 mg/kg, and the latex endowed free radical inhibition activity (IC₅₀ = 10.25 μg/ml). The latex of A. weloensis leaf demonstrated the inhibitory activity against the 3D7 strain of P. falciparum (IC₅₀ = 9.14 μg/ml). The prophylactic and curative effect of the latex was found to be dose-dependent. The mice's parasitemia level was significantly (p < 0.001) reduced at all tested doses of the leaf latex compared to negative control in the curative test. Parasitemia reduction was significant (200 mg/kg, p < 0.01, and 400 and 600 mg/kg, p < 0.001) in the prophylactic test compared to the control. In addition, the leaf latex significantly (p < 0.01) improved mean survival time, packed cell volume, rectal temperature, and bodyweight of P. berghei infected mice.

Conclusion

The leaf latex of Aloe weloensis was endowed with the antimalarial activity at various doses, corroborating the plant's claimed traditional use.

Antimalarial Activity of Fagaropsis angolensis (Rutaceae) Crude Extracts and Solvent Fractions of Its Stem Bark Against Plasmodium berghei in Mice

BACKGROUND

A current challenge in malaria control and elimination is the progressive resistance to most antimalarial drugs which necessitates the discovery of new options. Hence, the current study was initiated to investigate the antimalarial activity of the stem bark of Fagaropsis angolensis in mice.

METHODS

The test material was extracted using 80% methanol in a cold maceration technique and further fractionated in solvents of varied polarity. Acute oral toxicity was assessed following the OECD guideline no. 425 protocol. Then, the antimalarial activities of the crude extract and the fractions were evaluated in a 4-day suppression test. Rane's test was also used to evaluate the curative potential of the n-butanol fraction that showed the highest effect during the 4-day suppressive test. Parameters such as parasitemia suppression, mean survival time, packed cell volume, rectal temperature, and body weight were determined to establish the activity.

RESULTS

The acute oral toxicity test indicated that the plant did not cause any signs of behavioral changes or mortality at 200 mg/kg limit dose. In a 4-day suppression test, a significant dose-dependent reduction in the parasitemia level and prolongation of survival time were observed (p<0.001) in all three doses of the crude extract compared with the negative control. The crude extract also exhibited a significant (p<0.001) protective effect in packed cell volume and rectal temperature decline in all three doses in a dose-dependent fashion compared with the negative control. Among all fractions, the n-butanol fraction displayed the highest effects in all parameters in the 4-day suppression test. In addition, the n-butanol fraction also showed a significant percentage of parasitemia suppression effects at all doses in Rane's test. Furthermore, higher free radical scavenging activity was observed in the n-butanol fraction and the 80% methanol extract.

CONCLUSION

This study established that Fagaropsis angolensis had shown potential antimalarial activity as evidenced by the significant effects in the different parameters, upholding its traditional use for the treatment of malaria and laying the foundation for further investigations.

The Effects of Silver Nanoparticles Biosynthesized Using Fig and Olive Extracts on Cutaneous leishmaniasis Induced Inflammation in Female Balb/c Mice

Leishmaniasis is a group of infectious and non-contagious severe parasitic diseases, caused by protozoans of the Leishmania genus. Natural products characterize a rich source of prospective chemical entities for the development of new effective drugs for neglected diseases. Scientific evaluation of medicinal plants has made it possible to use some metabolites from flavonoids and polyphenols compounds for the treatment of parasitic diseases. Therefore, we aimed in this study to evaluate the protective effect of Silver nanoparticles (Ag-NPs) biosynthesized using Fig and Olive extracts (NFO) against Cutaneous leishmaniasis in female Balb/c mice. A total of 70 mice were used and divided into seven groups. Treatment was initiated when local lesions were apparent, we found Fig and Olive extracts were found to be a good source for the synthesis of (Ag-NPs), their formation was confirmed by color change and stability in solution. Nanoparticles biosynthesized using Fig and Olive extracts induced a reduction in the average size of cutaneous leishmaniasis lesions compared with the untreated mice. Moreover, nanoparticles treatment decreased oxidative stress (LPO, NO), down regulation gene expression levels (TNF-α, IL-1β and BAX) and this antileishmanial activity of nanoparticles was associated with enhanced antioxidant enzyme activities. In addition, histopathological evaluation proved the antileishmanial activity of nanoparticles compared to the positive control. Therefore, we aimed in this study to evaluate the protective effect of silver nanoparticles biosynthesized using Fig and Olive extracts against cutaneous lesions induced by Leishmania major infection through their anti-inflammatory, antioxidant activities and faster clinical efficacy than standard pentavalent antimonial treatment.

Evaluation of in vivo anti-malarial potential of omidun obtained from fermented maize in Ibadan, Nigeria

BACKGROUND

The menace of resistance to anti-malarial drugs is a great challenge to malaria control, necessitating the search for new anti-malarial agents. This search has led to the exploration of natural products for efficacy in malaria therapy. Omidun is the supernatant of fermenting maize (ogi) slurry that has been widely investigated and reported to possess several health benefits and it is used traditionally as solvent for preparing anti-malarial herbs. However, there is no information on the anti-malarial activity of omidun itself. This study was conducted to investigate the prophylactic, curative and suppressive anti-malarial potential of omidun.

METHODS

Experimental mice in the curative group were infected with 1 × 106 cells of Plasmodium berghei strain ANKA and treated with either 0.2 ml of omidun containing 3 × 109 cfu/ml of viable lactic acid bacteria or 0.2 ml of 5 mg/kg of chloroquine (positive control) or 0.2 ml of saline (negative control) for 4 days from day 3 post infection. The prophylactic group of mice were pre-treated with either omidun, chloroquine or saline for 4 days before infection with P. berghei, while the suppressive group was treated with omidun or chloroquine or saline and infected with P. berghei simultaneously. A group of mice were uninfected but treated (with omidun and control samples), while a final group was uninfected and untreated (controls). Parasitaemia and histopathology analysis were done in all groups.

RESULTS

The curative and suppressive groups showed a significant difference between the omidun-treated mice (100% parasitaemia reduction) and the untreated mice (54.5% parasitaemia increase). There was no significance difference between the omidun treatment and chloroquine (positive control) treatment in suppressive group as both treatment had 100% parasitaemia reduction. The omidun prophylactic treatment however did not show any parasitaemia suppression, but a significant difference was observed between the omidun treatment (85% increase) and the chloroquine (positive control) treatment (100% reduction) in the group. Omidun treatment is non-toxic to the kidney.

CONCLUSION

This study provides scientific evidence supporting omidun usage in the treatment of malaria. Consequently, further work may yield the specific component of omidun responsible for the anti-malarial activity.

Chemo Suppressive and Curative Potential of Hypoestes forskalei Against Plasmodium berghei: Evidence for in vivo Antimalarial Activity

Background

The emergence of drug resistance together with the global burden of malaria triggers the necessity for the searching of new antimalarial agents. This study, therefore, was initiated to investigate the in vivo antimalarial activity of Hypoestes forskalei in mice based on the strong supported evidence from the ethnobotanical claims and the in vitro anti-plasmodial activity of the plant.

Methods

The 4-day suppressive (crude extract and fractions) and the Rane’s (n-butanol fraction) tests were used to evaluate the antimalarial activity of the plant. A cold maceration technique with 80% methanol was used for the crude extraction of the plant. The crude extract was then fractionated using solvents of different polarity (chloroform, n-butanol, and water).

Results

All the test doses of the crude extract as well as the fractions reduced parasitemia and prolonged mean survival time significantly (P<0.001) as compared to their negative control groups. Maximum parasitemia suppression effect (56%) was observed at the highest dose (600 mg/kg) of the crude extract during the 4-day suppressive test. Likewise, the n-butanol, chloroform, and aqueous fractions showed a percentage suppression of about 50, 38, and 19, respectively, at the dose of 600 mg/kg. Therefore, the n-butanol fraction showed the highest parasitemia suppression followed by the chloroform fraction and then the aqueous fraction. Moreover, the n-butanol fraction showed a significant curative effect (P<0.001) in Rane’s test with a percentage suppression of about 49 at a dose of 600 mg/kg.

Conclusion

The study has revealed that the plant has a promising antimalarial activity, the activity being more in the crude extract than the fractions. The highest antimalarial activity of the n-butanol fraction suggests that non-polar and medium polar principles could be responsible for the observed activity.

Methnaridine is an orally bioavailable, fast-killing and long-acting antimalarial agent that cures Plasmodium infections in mice

BACKGROUND AND PURPOSE

Malaria is one of the deadliest diseases in the world. Novel chemotherapeutic agents are urgently required to combat the widespread Plasmodium resistance to frontline drugs. Here, we report the discovery of a novel benzonaphthyridine antimalarial, methnaridine, which was identified using a structural optimization strategy.

EXPERIMENTAL APPROACH

An integrated pharmacological approach was used to evaluate the antimalarial profile of methnaridine. The pharmacokinetic properties of methnaridine were investigated along with the associated safety profile. Host immune response patterns were also analysed.

KEY RESULTS

Methnaridine exhibited potent antimalarial activity against P. falciparum (3D7: IC₅₀ = 0.0066 μM; Dd2: IC₅₀ = 0.0056 μM). In P. berghei-infected mice, oral administration effectively suppressed parasitemia (ED₅₀ = 0.52 mg·kg^-1 ·day^-1 ) and cured the established infection (CD₅₀ = 10.13 mg·kg^-1 ·day^-1 ). These results are equivalent to or better than those of other antimalarial agents in clinical use. Notably, a four-dose oral regimen at a dosage of 25 mg·kg^-1 achieved a complete cure of P. berghei infection in mice. Methnaridine exhibited a rapid parasiticidal profile (PCT₉₉ = 36.0 h) and showed no cross-resistance to chloroquine. Pharmacokinetic studies revealed that methnaridine is readily absorbed, long-lasting and slowly cleared. The safety profile of methnaridine is also satisfactory (maximum tolerated dose = 1,125 mg·kg^-1 ). In addition, following methnaridine treatment, infection-induced Th1 immune response was almost fully alleviated in mice.

CONCLUSION AND IMPLICATIONS

Methnaridine is an orally bioavailable, fast-acting and long-lasting agent with excellent antimalarial properties. Our study highlights the potential of methnaridine for clinical development as a promising antimalarial candidate.