3D7 Strain Research Articles

Bioguided Fractionation and Isolation of an Antiplasmodial Saponin from the Roots of Nauclea xanthoxylon (A.Chev.) Aubrév. (Rubiaceae).

The root extract of Nauclea xanthoxylon (A.Chev.) Aubrév. displayed significant 50 % inhibition concentration (IC50 s) of 0.57 and 1.26 μg/mL against chloroquine resistant and sensitive Plasmodium falciparum (Pf) Dd2 and 3D7 strains, respectively. Bio-guided fractionation led to an ethyl acetate fraction with IC50 s of 2.68 and 1.85 μg/mL and subsequently, to the new quinovic acid saponin named xanthoxyloside (1) with IC50 s of 0.33 and 1.30 μM, respectively against the tested strains. Further compounds obtained from ethyl acetate and hexane fractions were the known clethric acid (2), ursolic acid (3), quafrinoic acid (4), quinovic acid (5), quinovic acid 3-O-β-D-fucopyranoside (6), oleanolic acid (7), oleanolic acid 3-acetate (8), friedelin (9), β-sitosterol (10a), stigmasterol (10b) and stigmasterol 3-O-β-D-glucopyranoside (11). Their structures were characterised with the aid of comprehensive spectroscopic methods (1 and 2D NMR, Mass). Bio-assays were performed using nucleic acid gel stain (SYBR green I)-based fluorescence assay with chloroquine as reference. Extracts and compounds exhibited good selectivity indices (SIs) of >10. Significant antiplasmodial activities measured for the crude extract, the ethyl acetate fraction and xanthoxyloside (1) from that fraction can justify the use of the root of N. xanthoxylon in ethnomedicine to treat malaria.

Comparative Assessment of the Antiplasmodial Activity and Acute Toxicity of Schumanniophyton magnificum Good & Halle (Rubiaceae) Leaves, Trunk and Roots Methanolic Extracts

Background: Despite the various medicinal applications of Schumanniophyton magnificum, no comparative data are available to determine the part with best antiplasmodial activity and to guarantee its safety. This work deals with the evaluation of the antiplasmodial activity of methanolic extracts of S. magnificum organs as well as the study of acute toxicity of the most active part.
 Materials and methods: The methanolic extracts of the leaves, stem bark, trunk wood, root wood and root bark, were obtained by maceration with 96% methanol. Phytochemical screening, based on precipitation and coloring reactions, to highlight the chemical groups present in the plant. The antiplasmodial test was ran against chloroquine sensitive Plasmodium falciparum 3D7 strains while the study of the in vivo acute toxicity was conducted according to guideline 423 of the OECD protocol at a fixed dose on Wistar rats.
 Results: Phytochemical screening of the methanol extracts of these plants organs revealed the presence of alkaloids, triterpenoids, saponins, anthraquinones, polyphenols, coumarins anthocyanins and flavonoids. The antiplasmodial activity showed that only the leaves exhibited a moderate antiplasmodial effect with IC50 of 30.77 µg/ml. An oral administration of the methanolic extract of the leaves did not induce an abnormal variation of the physiological parameters in female Wistar laboratory rats, at non-toxic doses of 50, 300 and 2000 mg/kg body weight for 14 days.
 Conclusion: The leaves of S. magnificum exhibited the best antimalarial activity and were non toxic, thus justifying the use of the plant in the treatment of malaria in traditional pharmacopoeia.
 Keywords: Phytochemical screening, Antiplasmodial activity, Acute toxicity, Schumanniophyton magnificum, Medicinal plant.

Establishment and preliminary evaluation of a fluorescent recombinase-aided amplification/CRISPR-Cas12a system for rapid detection of Plasmodium falciparum

To establish a fluorescent assay for rapid detection of Plasmodium falciparum based on recombinaseaided amplification (RAA) and CRISPR-Cas12a system,and to preliminarily evaluate the diagnostic efficiency of this system. The 18S ribosomal RNA (rRNA) gene of P. falciparum was selected as the target sequence, and three pairs of RAA primers and CRISPR-derived RNA (crRNA) were designed and synthesized. The optimal combination of RAA primers and crRNA was screened and the reaction conditions of the system were optimized to create a fluorescent RAA/CRISPR-Cas12a system. The plasmid containing 18S rRNA gene of the P. falciparum strain 3D7 was generated, and diluted into concentrations of 1 000, 100, 10, 1 copy/μL for the fluorescent RAA/CRISPR-Cas12a assay, and its sensitivity was evaluated. The genomic DNA from P. vivax, P. malariae, P. ovum, hepatitis B virus, human immunodeficiency virus and Treponema pallidum was employed as templates for the fluorescent RAA/CRISPR-Cas12a assay, and its specificity was evaluated. Fifty malaria clinical samples were subjected to the fluorescent RAA/CRISPR-Cas12a assay and nested PCR assay, and the consistency between two assays was compared. In addition, P. falciparum strain 3D7 was cultured in vitro. Then, the culture was diluted into blood samples with parasite densities of 1 000, 500, 200, 50, 10 parasites/μL with healthy volunteers' O-positive red blood cells for the RAA/CRISPR-Cas12a assay, and the detection efficiency was tested. The Pf-F3/Pf-R3/crRNA2 combination, 2.5 μL as the addition amount of B buffer, 40 min as the RAA reaction time, 37 °C as the reaction temperature of the CRISPR-Cas12a system were employed to establish the fluorescent RAA/CRISPR-Cas12a system. Such a system was effective to detect the plasmid containing 18S rRNA gene of the P. falciparum strain 3D7 at a concentration of 1 copy/μL, and presented fluorescent signals for detection of P. falciparum, but failed to detect P. ovum, P. malariae, P. vivax, T. pallidum, hepatitis B virus or human immunodeficiency virus. The fluorescent RAA/CRISPR-Cas12a system and nested PCR assay showed completely consistent results for detection of 50 malaria clinical samples (kappa = 1.0, P < 0.001). Following 6-day in vitro culture of the P. falciparum strain 3D7, 10 mL cultures were generated and the fluorescent RAA/CRISPR-Cas12a system showed the minimal detection limit of 50 parasites/μL. The fluorescent RAA/CRISPR-Cas12a system is rapid, sensitive and specific for detection of P. falciparum, which shows promising value for rapid detection and risk monitoring of P. falciparum.

Senna occidentalis (L.) Link root extract inhibits Plasmodium growth in vitro and in mice

BackgroundSenna occidentalis (L.) Link has been used worldwide in traditional treatment of many diseases and conditions including snakebite. In Kenya, a decoction from the plant roots taken orally, is used as a cure for malaria. Several studies have demonstrated that extracts from the plant possess antiplasmodial activity, in vitro. However, the safety and curative potency of the plant root against established malaria infection is yet to be scientifically validated, in vivo. On the other hand, there are reports on variation in bioactivity of extracts obtained from this plant species, depending on the plant part used and place of origin among other factors. In this study, we demonstrated the antiplasmodial activity of Senna occidentalis roots extract in vitro, and in mice.MethodsMethanol, ethyl acetate, chloroform, hexane and water extracts of S. occidentalis root were tested for in vitro antiplasmodial activity against Plasmodium falciparum, strain 3D7. Cytotoxicity of the most active solvent extracts was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the curative potency in Plasmodium berghei infected mice evaluated by Rane’s test.ResultsAll of the solvent extracts tested in this study inhibited the propagation of P. falciparum, strain 3D7, in vitro, with polar extracts being more active than non-polar ones. Methanolic extracts had the highest activity (IC50 = 1.76) while hexane extract displayed the lowest activity (IC50 = 18.47). At the tested concentrations, methanolic and aqueous extracts exhibited high selectivity index against P. falciparum strain 3D7 (SI > 10) in the cytotoxicity assay. Further, the extracts significantly suppressed the propagation of P. berghei parasites (P < 0.05) in vivo and increased the survival time of the infected mice (P < 0.0001).ConclusionsSenna occidentalis (L.) Link root extract inhibits the propagation of malaria parasites in vitro and in BALB/c mice.

English

In the current study, strain D1 was screened from saline-alkali soil of grassland by the method of plate confrontation. The inhibition rates against Fusarium equiseti BS1 , Fusarium oxysporum BF28 , Fusarium oxysporum BF19 and Fusarium solami BF36-2 were 70.81% , 76.00% , 67.80% and 65.70% respectively. Strain D1 was identified as Streptomyces ciscaucasicus by observation of colony morphology, physiological and biochemical characteristics and sequence analysis of 16S rRNA gene. The results of antimicrobial spectrum showed that the strain had antagonistic effect against 9 kinds of plant pathogenic fungi. The control effect of the strain on alfalfa root rot was 52.8% and it could promote rooting. The results showed that the strain D1 had potential as a biological agent

Phytofabrication and characterization of Alchornea cordifolia silver nanoparticles and evaluation of antiplasmodial, hemocompatibility and larvicidal potential.

Purpose: The recent emergence of Plasmodium falciparum (Pf) parasites resistant to current artemisinin-based combination therapies in Africa justifies the need to develop new strategies for successful malaria control. We synthesized, characterized and evaluated medical applications of optimized silver nanoparticles using Alchornea cordifolia (AC-AgNPs), a plant largely used in African and Asian traditional medicine. Methods: Fresh leaves of A. cordifolia were used to prepare aqueous crude extract, which was mixed with silver nitrate for AC-AgNPs synthesis and optimization. The optimized AC-AgNPs were characterized using several techniques including ultraviolet-visible spectrophotometry (UV-Vis), scanning/transmission electron microscopy (SEM/TEM), powder X-ray diffraction (PXRD), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX), Fourier transformed infrared spectroscopy (FTIR), dynamic light scattering (DLS) and Zeta potential. Thereafter, AC-AgNPs were evaluated for their hemocompatibility and antiplasmodial activity against Pf malaria strains 3D7 and RKL9. Finally, lethal activity of AC-AgNPs was assessed against mosquito larvae of Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti which are vectors of neglected diseases such as dengue, filariasis and chikungunya. Results: The AC-AgNPs were mostly spheroidal, polycrystalline (84.13%), stable and polydispersed with size of 11.77 ± 5.57nm. FTIR revealed the presence of several peaks corresponding to functional chemical groups characteristics of alkanoids, terpenoids, flavonoids, phenols, steroids, anthraquonones and saponins. The AC-AgNPs had a high antiplasmodial activity, with IC50 of 8.05μg/mL and 10.31μg/mL against 3D7 and RKL9 Plasmodium falciparum strains. Likewise, high larvicidal activity of AC-AgNPs was found after 24h- and 48h-exposure: LC50 = 18.41μg/mL and 8.97μg/mL (Culex quinquefasciatus), LC50 = 16.71μg/mL and 7.52μg/mL (Aedes aegypti) and LC50 = 10.67μg/mL and 5.85μg/mL (Anopheles stephensi). The AC-AgNPs were highly hemocompatible (HC50 > 500μg/mL). Conclusion: In worrying context of resistance of parasite and mosquitoes, green nanotechnologies using plants could be a cutting-edge alternative for drug/insecticide discovery and development.

Antiplasmodial and Antioxidant Activity of Garcinia Bancana Extract

Malaria caused by Plasmodium parasites is a significant public health issue, particularly in tropical and subtropical regions. There is also resistance to chloroquine-based therapy, which highlights the need for novel therapeutic agents. Therefore, our project in exploring antiplasmodial agents from Garcinia Indonesia continues. This study evaluates the phytochemical content of G. bancana by the total phenolic content (TPC) and total flavonoid content (TFC) and its in vitro antioxidant and antiplasmodial activities. The TPC and TFC values were determined using a UV-VIS spectrophotometer, while the antioxidant activity was determined using the DPPH, ABTS, and FRAP assays. Antiplasmodial activity against a chloroquine-sensitive strain 3D7 was evaluated using the Giemsa staining method. The highest TPC value of 195.75 ± 1.24 mg GAE/g was obtained from methanolic extract, while a TFC value of 82.79 ± 0.34 mg QE/g extract was found from dichloromethane extract. The methanolic extract exhibited the most potent antioxidant activity in the DPPH and FRAP assays with IC50 values of 6.07 ± 0.06 μg/ml and 74.35 ± 3.77 μM Fe2+/g, respectively. The n-hexane extract was found to be the most potent on ABTS antioxidant and antiplasmodial assays with IC50 values of 1.22 ± 0.02 μg/ml and 0.23 ± 0.01 μg/ml, respectively. Furthermore, the DPPH antioxidant was negatively correlated with antiplasmodial significantly at 0.05. These findings suggest that the n-hexane extract of G. bancana has great potential as a source of antioxidant and antiplasmodial compounds. To the best of our knowledge, this study provides microscopic evidence in addition to the strongest antiplasmodial efficacy of Garcinia extract.

Rubia cordifolia L. Crude Aerial Part Extracts Show a High Potential as Antimalarials against Chloroquine Resistant Plasmodium falciparum Strains in vitro

Pharmacognosy Research,2023,15,2,288-296.DOI:10.5530/pres.15.2.031Published:February 2023Type:Original Article Authors:Magara Jeremiah, Lucy Kamau, Grace Nyambati, and Hastings Ozwara Author(s) affiliations:Magara Jeremiah1, Lucy Kamau1, 2,*, Grace Nyambati3, Hastings Ozwara4 1Department of Zoological Sciences, Kenyatta University, Nairobi, KENYA. 2Department of Animal Sciences, Kenyatta University, Nairobi, KENYA. 3Department of Biomedical Sciences and Technology, The Technical University of Kenya, Nairobi, KENYA. 4Department of Tropical and Infectious Diseases, Institute of Primate Research, Nairobi, KENYA. Abstract:Introduction: Plasmodium falciparum human malaria parasite is resistant to most available medicines in Africa, necessitating research for new drugs. Rubia cordifolia L. is used in traditional malaria treatment in Kenya despite no supporting scientific data. Objectives: To evaluate anti-plasmodial efficacy of extracts from the aerial part of Rubia cordifolia against chloroquine sensitive (3D7) and resistant (W2) Plasmodium falciparum strains. Methods: Hexane, methanol and water were separately used in crude extractions from open shade dried aerial plant parts. Phytochemical composition was determined qualitatively. Anti-plasmodial efficacy of serial dilutions (range; 0.4 to 50 μg/ml) of each extract were evaluated in vitro and compared using ANOVA and Tukey’s HSD test, at p<0.05). Results: All the extracts significantly inhibited parasites growth, in a dose dependent manner. At 50 μg/ml, inhibition was (84.07%, 77.94% and 66.08%) for hexane, methanol and water extracts respectively against W2 and (80.06%, 78.36% and 60.92%) against 3D7 strain. Hexane extract showed IC50 0.551 μg/ml and 2.747 micrograms/ml against W2 and 3D7 respectively. Methanol extract, IC50 1.231 and 3.528 μ g/ml respectively, aqueous extract showed moderate activity, IC50 5.348 μg/ml and 17.341 μg/ml against the strains respectively. Chloroquine resistant (W2 strain) was more responsive to the extracts than 3D7 strain. Conclusion: Anti-plasmodial activities were in the order, Hexane>methanol>aqueous and were attributed to the phytochemicals present in the extracts. This presents evidence of R. cordifolia as anti-malarial drugs’ source. Further work is required to identify, purify, and characterize active molecules for development of anti-malaria drugs. Keywords:Antimalarial activity, Crude extracts, in vitro, Plasmodium falciparum, Rubia cordifolia.View:PDF (236.96 KB)

Constituents of the Stem Bark of Trichilia monadelpha (Thonn.) J. J. De Wilde (Meliaceae) and Their Antibacterial and Antiplasmodial Activities

The chemical investigation of the EtOH extract from the stem bark of Trichilia monadelpha (Thonn.) J. J. De Wilde afforded two new limonoids (1 and 2): 24-acetoxy-21,25-dihydroxy-21,23-epoxytirucall-7-en-3-one (1) and (6R)-1-O-deacetylkhayanolide E (2), together with eleven known compounds (3-13), including additional limonoids, flavonoids, triterpenoids, steroids, and fatty acid. Their structures were determined using 1D- and 2D-NMR experiments, ESI mass spectrometry, and single crystal X-ray diffraction analysis. The antibacterial and antiplasmodial activities of the extracts, sub-extracts, fractions, and some of the isolated compounds were evaluated in known pathogenic strains, including Staphylococcus aureus and Plasmodium falciparum. Fraction E (n-Hex/EtOAc 30:70, v/v) showed significant activity against S. aureus ATCC 25923 with a MIC value of 3.90 µg/mL, while one of its constituents (epicatechin (9)) exhibited significant activity with MIC values of 7.80 µg/mL. Interestingly, grandifotane A (6) (IC50 = 1.37 µM) and khayanolide D (5) (IC50 = 1.68 µM) were highly active against the chloroquine-sensitive/sulfadoxine-resistant plasmodium falciparum 3D7 strain, unlike their corresponding plant extract and fractions.

In vitro and in vivo antiplasmodial activities of leaf extracts from Sonchus arvensis L.

BackgroundMalaria continues to be a global problem due to the limited efficacy of current drugs and the natural products are a potential source for discovering new antimalarial agents. Therefore, the aims of this study were to investigate phytochemical properties, cytotoxic effect, antioxidant, and antiplasmodial activities of Sonchus arvensis L. leaf extracts both in vitro and in vivo.MethodsThe extracts from S. arvensis L. leaf were prepared by successive maceration with n-hexane, ethyl acetate, and ethanol, and then subjected to quantitative phytochemical analysis using standard methods. The antimalarial activities of crude extracts were tested in vitro against Plasmodium falciparum 3D7 strain while the Peter's 4-day suppressive test model with P. berghei-infected mice was used to evaluate the in vivo antiplasmodial, hepatoprotective, nephroprotective, and immunomodulatory activities. The cytotoxic tests were also carried out using human hepatic cell lines in [3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay.ResultThe n-hexane, ethyl acetate, and ethanolic extracts of S. arvensis L. leaf exhibited good in vitro antiplasmodial activity with IC50 values 5.119 ± 3.27, 2.916 ± 2.34, and 8.026 ± 1.23 μg/mL, respectively. Each of the extracts also exhibited high antioxidant with low cytotoxic effects. Furthermore, the ethyl acetate extract showed in vivo antiplasmodial activity with ED50 = 46.31 ± 9.36 mg/kg body weight, as well as hepatoprotective, nephroprotective, and immunomodulatory activities in mice infected with P. berghei.ConclusionThis study highlights the antiplasmodial activities of S. arvensis L. leaf ethyl acetate extract against P. falciparum and P. berghei as well as the antioxidant, nephroprotective, hepatoprotective, and immunomodulatory activities with low toxicity. These results indicate the potential of Sonchus arvensis L. to be developed into a new antimalarial drug candidate. However, the compounds and transmission-blocking strategies for malaria control of S. arvensis L. extracts are essential for further study.

In Vitro Antiplasmodial, Cytotoxicity, and Antioxidant Activities of Lophira lanceolata (Ochnaceae): A Cameroonian Plant Commonly Used to Treat Malaria.

Malaria is the leading cause of morbidity and mortality in African countries. We aimed this study at evaluating the in vitro antiplasmodial, antioxidant, and cytotoxicity activity of Lophira lanceolata extracts. The aqueous and ethanol extracts were obtained by maceration. It tested in vitro the extracts against Plasmodium falciparum 3D7 and multiresistance Dd2. Macrophage cell lines (RAW 264.7 cells) and red blood cells were used for cytotoxicity tests. The antioxidant activity was assessed by 1,1-diphenyl-2-picrylhydrazine (DPPH), hydrogen peroxide (H2O2), nitric oxide (NO) reduction, and ferric reducing antioxidant power (FRAP) scavenging. The in vitro antiplasmodial results showed that the ethanol extract was the most active, with IC50 of 24.51 ± 4.77 µg/mL and 31.86 ± 3.10 µg/mL, respectively, on the resistant Dd2 and sensitive 3D7 strains unlike the aqueous which indicated moderate activity with an IC50 of 51.36 ± 4.86 μg/mL and 56.36 ± 4.27 μg/mL, respectively, on the resistant Dd2 and sensitive (3D7) strains. However, the ethanol extract had the highest activity, with an IC50 of 8.153 g/mL, 1915 g/mL, 30.81 g/mL, and 54.66 g/mL, respectively, for DPPH, H2O2, NO, and FRAP, while the aqueous extract had an IC50 of 6.724, 2387681, 185.7, and 152.0 g/mL, respectively, for DPPH, H2O2, NO, and FRAP. The cytotoxicity test reveals that both extracts do not promote red blood cell haemolysis. They presented weak activity against RAW 264.7 cells and red blood cells. According to these findings, the aqueous and ethanol extracts have antiplasmodial and antioxidant activity but with no cytotoxic effects on red blood cells or RAW cells. However, it will be important to investigate the in vivo antiplasmodial and antioxidant activity of these extracts.

Structure-Based Optimization of Protease-Inhibitor Interactions to Enhance Specificity of Human Stefin-A against Falcipain-2 from the Plasmodium falciparum 3D7 Strain.

The emergence of resistance in Plasmodium falciparum to frontline artemisinin-based combination therapies has raised global concerns and emphasized the identification of new drug targets for malaria. Cysteine protease falcipain-2 (FP2), involved in host hemoglobin degradation and instrumental in parasite survival, has long been proposed as a promising malarial drug target. However, designing active-site-targeted small-molecule inhibitors of FP2 becomes challenging due to their off-target specificity toward highly homologous human cysteine cathepsins. The use of proteinaceous inhibitors, which have nonconserved exosite interactions and larger interface area, can effectively circumvent this problem. In this study, we report for the first time that human stefin-A (STFA) efficiently inhibits FP2 with Ki values in the nanomolar range. The FP2-STFA complex crystal structure, determined in this study, and sequence analyses identify a unique nonconserved exosite interaction, compared to human cathepsins. Designing a mutation Lys68 > Arg in STFA amplifies its selectivity garnering a 3.3-fold lower Ki value against FP2, and the crystal structure of the FP2-STFAK68R complex shows stronger electrostatic interaction between side-chains of Arg68 (STFAK68R) and Asp109 (FP2). Comparative structural analyses and molecular dynamics (MD) simulation studies of the complexes further confirm higher buried surface areas, better interaction energies for FP2-STFAK68R, and consistency of the newly developed electrostatic interaction (STFA-R68-FP2-D109) in the MD trajectory. The STFA-K68R mutant also shows higher Ki values against human cathepsin-L and stefin, a step toward eliminating off-target specificity. Hence, this work underlines the design of host-based proteinaceous inhibitors against FP2, with further optimization to render them more potent and selective.

Challenges Based on Antiplasmodial and Antiviral Activities of 7-Chloro-4-aminoquinoline Derivatives.

We report the structural functionalization of the terminal amino group of N1 -(7-chloroquinolin-4-yl) butane-1,4-diamine, leading to a series of 7-chloro-4-aminoquinoline derivatives, and their evaluation as potent anti-malarial and anti-viral agents. Some compounds exhibited promising anti-malarial effects against the Plasmodium falciparum 3D7 (chloroquine-sensitive) and Dd2 (chloroquine-resistant) strains. In addition, these compounds were assayed in vitro against influenza A virus (IAV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Compound 5 h, bearing an N-mesityl thiourea group, displayed pronounced anti-infectious effects against malaria, IAV, and SARS-CoV-2. These results provide new insights into drug discovery for the prevention or treatment of malaria and virus co-infection.

Comparative Anti-plasmodial and Cytotoxic Effect of the Methanolic Extracts of Leaves, Stem Bark and Roots of Annickia affinis

Aims: This study aimed to evaluate and compare the in vitro anti-plasmodial and cytotoxic effect of the methanolic extracts from leaves, stem bark and roots of Annickia affinis.&#x0D; Study Design: This is an experimental study.&#x0D; Place and Duration of Study: The work was conducted at the Pharmacochemistry and Natural Substances Laboratories of the Faculty of Medicine and Pharmaceutical Sciences, University of Douala for the extraction and at the Biomedical Chemistry Research Center of Rhodes University in South Africa for the antimalarial and cytotoxic essay. All the experiments were carried out from the 15th October 2019 to the 31th July 2020.&#x0D; Methodology: The anti-plasmodial test was performed on Plasmodium falciparum sensitive strains 3D7 while cytotoxicity was evaluated on the HeLa cell line.&#x0D; Results: The anti-plasmodial tests revealed that the roots and the stem bark exhibited a moderate anti-plasmodial effect with IC50 of 19.7 ± 0.8 and 12.1 ± 0.8 µg/ml respectively. The anti-plasmodial effects of the leaves were classified as low (33.7 ± 1.9 µg/ml). At up to 50 µg/ml, all the extracts showed a high rate of survival among the HeLa cells. No effect was observed with the leaf extracts (100% of survival).&#x0D; Conclusion: This is the first report on the cytotoxic study and comparative anti-plasmodial effect of Annikia affinis. It highlights the potential of Annickia affinis as an important source of anti-plasmodial drugs with less cytotoxic in vitro. In agreement with the use in traditional medicine, the stem bark was more active than wood, while leaves showed low activity.

Synthesis and characterisation of new antimalarial fluorinated triazolopyrazine compounds.

Nine new fluorinated analogues were synthesised by late-stage functionalisation using Diversinate™ chemistry on the Open Source Malaria (OSM) triazolopyrazine scaffold (Series 4). The structures of all analogues were fully characterised by NMR, UV and MS data analysis; three triazolopyrazines were confirmed by X-ray crystal structure analysis. The inhibitory activity of all compounds against the growth of the malaria parasite Plasmodium falciparum (3D7 and Dd2 strains) and the cytotoxicity against a human embryonic kidney (HEK293) cell line were tested. Some of the compounds demonstrated moderate antimalarial activity with IC50 values ranging from 0.2 to >80 µM; none of the compounds displayed any cytotoxicity against HEK293 cells at 80 µM. Antimalarial activity was significantly reduced when C-8 of the triazolopyrazine scaffold was substituted with CF3 and CF2H moieties, whereas incorporation of a CF2Me group at the same position completely abolished antiplasmodial effects.

Squaramide Tethered Clindamycin, Chloroquine, and Mortiamide Hybrids: Design, Synthesis, and Antimalarial Activity.

Malaria remains one of the major health problems in the world. In this work, a series of squaramide tethered chloroquine, clindamycin, and mortiamide D hybrids have been synthesized to assess their in vitro antiplasmodial activity against 3D7 (chloroquine-sensitive) and Dd2 strains of Plasmodium falciparum. The most active compound, a simple chloroquine analogue, displayed low nanomolar IC50 value against both strains (3 nM for 3D7 strain and 18 nM for Dd2 strain). Moreover, all molecular hybrids incorporating the hydroxychloroquine scaffold showed the most potent activities, exemplified with a chloroquine dimer, IC50 = 31 nM and 81 nM against 3D7 and Dd2 strains, respectively. These results highlight the first time use of clindamycin and mortiamide D as antimalarial molecular hybrids and establish these valuable hits for future optimization.

FT-GPI, a highly sensitive and accurate predictor of GPI-anchored proteins, reveals the composition and evolution of the GPI proteome in Plasmodium species

BackgroundProtozoan parasites are known to attach specific and diverse group of proteins to their plasma membrane via a GPI anchor. In malaria parasites, GPI-anchored proteins (GPI-APs) have been shown to play an important role in host–pathogen interactions and a key function in host cell invasion and immune evasion. Because of their immunogenic properties, some of these proteins have been considered as malaria vaccine candidates. However, identification of all possible GPI-APs encoded by these parasites remains challenging due to their sequence diversity and limitations of the tools used for their characterization.MethodsThe FT-GPI software was developed to detect GPI-APs based on the presence of a hydrophobic helix at both ends of the premature peptide. FT-GPI was implemented in C ++and applied to study the GPI-proteome of 46 isolates of the order Haemosporida. Using the GPI proteome of Plasmodium falciparum strain 3D7 and Plasmodium vivax strain Sal-1, a heuristic method was defined to select the most sensitive and specific FT-GPI software parameters.ResultsFT-GPI enabled revision of the GPI-proteome of P. falciparum and P. vivax, including the identification of novel GPI-APs. Orthology- and synteny-based analyses showed that 19 of the 37 GPI-APs found in the order Haemosporida are conserved among Plasmodium species. Our analyses suggest that gene duplication and deletion events may have contributed significantly to the evolution of the GPI proteome, and its composition correlates with speciation.ConclusionFT-GPI-based prediction is a useful tool for mining GPI-APs and gaining further insights into their evolution and sequence diversity. This resource may also help identify new protein candidates for the development of vaccines for malaria and other parasitic diseases.

Low-dose intravenous and subcutaneous CIS43LS monoclonal antibody for protection against malaria (VRC 612 Part C): a phase 1, adaptive trial

Human monoclonal antibodies might offer an important new approach to reduce malaria morbidity and mortality. In the first two parts of a three-part clinical trial, the antimalarial monoclonal antibody CIS43LS conferred high protection against parasitaemia at doses of 20 mg/kg or 40 mg/kg administered intravenously followed by controlled human malaria infection. The ability of CIS43LS to confer protection at lower doses or by the subcutaneous route is unknown. We aimed to provide data on the safety and optimisation of dose and route for the human antimalaria monoclonal antibody CIS43LS. VRC 612 Part C was the third part of a three-part, first-in-human, phase 1, adaptive trial, conducted at the University of Maryland, Baltimore Center for Vaccine Development and Global Health, Baltimore, MD, USA. We enrolled adults aged 18-50 years with no previous malaria vaccinations or infections, in a sequential, dose-escalating manner. Eligible participants received the monoclonal antibody CIS43LS in a single, open-label dose of 1 mg/kg, 5 mg/kg, or 10 mg/kg intravenously, or 5 mg/kg or 10 mg/kg subcutaneously. Participants underwent controlled human malaria infection by the bites of five mosquitoes infected with Plasmodium falciparum 3D7 strain approximately 8 weeks after their monoclonal antibody inoculation. Six additional control participants who did not receive CIS43LS underwent controlled human malaria infection simultaneously. Participants were followed-up daily on days 7-18 and day 21, with qualitative PCR used for P falciparum detection. Participants who tested positive for P falciparum were treated with atovaquone-proguanil and those who remained negative were treated at day 21. Participants were followed-up until 24 weeks after dosing. The primary outcome was safety and tolerability of CIS43LS at each dose level, assessed in the as-treated population. Secondary outcomes included protective efficacy of CIS43LS after controlled human malaria infection. This trial is now complete and is registered with ClinicalTrials.gov, NCT04206332. Between Sept 1, 2021, and Oct 29, 2021, 47 people were assessed for eligibility and 31 were enrolled (one subsequently withdrew and was replaced) and assigned to receive doses of 1 mg/kg (n=7), 5 mg/kg (n=4), and 10 mg/kg (n=3) intravenously and 5 mg/kg (n=4) and 10 mg/kg (n=4) subcutaneously, or to the control group (n=8). CIS43LS administration was safe and well tolerated; no serious adverse events occurred. CIS43LS protected 18 (82%) of 22 participants who received a dose. No participants developed parasitaemia following dosing at 5 mg/kg intravenously or subcutaneously, or at 10 mg/kg intravenously or subcutaneously. All six control participants and four of seven participants dosed at 1 mg/kg intravenously developed parasitaemia after controlled human malaria infection. CIS43LS was safe and well tolerated, and conferred protection against P falciparum at low doses and by the subcutaneous route, providing evidence that this approach might be useful to prevent malaria across several clinical use cases. National Institute of Allergy and Infectious Diseases, National Institutes of Health.

Antioxidant, Antimicrobial, and Antiplasmodial Activities of Sonchus arvensis L. Leaf Ethyl Acetate Fractions

Infection is one of the health problems and a disease that mainly causes death. Malaria is a parasitic infection that is transmitted through the Anopheles sp. The female then causes infection and besides malaria, other contaminants that caused infection are bacteria such as Escherichia coli and Staphylococcus aureus. This study aims to determine the antioxidant, antimicrobial, and antiplasmodial activity of Sonchus arvensis L. ethyl acetate fractions. In vitro antiplasmodial activity was carried out by Rieckman methods against Plasmodium falciparum strain 3D7. In vitro antioxidant activity was conducted by Prieto method against (1,1-diphenyl-2-picrylhydrazyl (DPPH). Then antimicrobial activity was performed using well diffusion method against Escherichia coli and Staphylococcus aureus. Maceration of S. arvensis L. dried leaves used n-hexane and ethyl acetate successively. Then the ethyl acetate extract was fractionated by vacuum column chromatography, using n-hexane and ethyl acetate as mobile phases. There are five fraction groups based on thin-layer chromatography (TLC) analysis. The IC50 of antioxidant and antiplasmodial activity showed that fraction IV was the lowest value and categorized as active for antioxidant (IC50=22.56 μg/mL), for antiplasmodial (IC50=12.07 μg/mL). Fraction IV also had antimicrobial activity, with diameter of inhibition zone (DIZ) of 19.22 mm against Escherichia coli and 17.167 mm against Staphylococcus aureus.

In-vitro Antiplasmodial Efficacy of a Poly Herbal Formulation against Plasmodium falciparum (3D7 Strain)

Malaria is one of the world's leading killer infectious diseases accounting for about 241 million cases of infection and 627000 deaths all around the globe in the year of 2021. In the present study, a polyherbal formulation used by traditional drug practitioners to cure malarial infection in some rural areas of Barpeta district of Assam, India was tested in vitro for its antiplasmodial and antioxidant properties. Two plant species namely Aristolochia indica L. and Piper nigrum L. were used for the herbal formulation. Water extract along with other organic solvent extracts viz. Chloroform, 2-propanol, methanol and n-hexane was tested in the experiment. Methanol and 2-propanol extracts in high concentration (50µg/ml) showed promising antiplasmodial effect in 3D7 strain of Plasmodium falciparum. Water extract showed promising antioxidant properties along with methanolic extract. This preliminary study conclusively established the antiplasmodial and antioxidant properties of the traditionally used polyherbal formulation. Further studies are required for the exploration of bioactive compounds from this formulation. Scientific validation of such traditional practices is important not only because there is an urgent need for alternative medication against diseases like malaria, but it is also important from the conservation point of view. These traditional herbal remedies lack proper documentation in scientific literature and the need of the hour is to explore their potential and proper documentation.