Ultrastructural alterations in Plasmodium falciparum induced by chalcone derivatives

Abstract Objective Chalcones (1, 3-diaryl-2-propen-1-ones) and its derivatives are widely explored from the past decade for its antimalarial activity. To elucidate their mechanism of action on the malaria parasite, the ultrastructural changes with the action of these derivatives in different organelles of the parasite were studied in vitro. Infected RBCs (CQ sensitive (MRC-2) and CQ resistant (RKL-9) Plasmodium strain) were treated with three chalcone derivatives 2, 6 and 7 and standard drugs, i.e., CQ and artemisinin at twice their respective IC50 values for 24 h and then harvested, washed, fixed, embedded and stained to visualize ultra-structure changes before and after intervention of treatment under in vitro condition through transmission electron microscope.Results The ultrastructural changes demonstrate the significant disturbance of all parasite membranes, including those of the nucleus, mitochondria and food vacuole, in association with a marked reduction of ribosomes in the trophozoites and cessation of developing schizonts which suggest multiple mechanisms of action by which chalcone derivatives act on the malaria parasite. The present study opens up perspectives for further exploration of these derivatives in vivo malaria model to discover more about its effect and mechanism of action.

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Antiplasmodial Activity of [(Aryl)arylsulfanylmethyl]Pyridine

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00898-07 ◽

2007 ◽

Vol 52 (2) ◽

pp. 705-715 ◽

Cited By ~ 40

Author(s):

Sanjay Kumar ◽

Sajal Kumar Das ◽

Sumanta Dey ◽

Pallab Maity ◽

Mithu Guha ◽

...

Keyword(s):

Oxidative Stress ◽

Malaria Parasite ◽

Spin Trap ◽

Antimalarial Activity ◽

Lipid Peroxide ◽

Food Vacuole ◽

Mitochondrial Potential ◽

Free Heme

ABSTRACT A series of [(aryl)arylsufanylmethyl]pyridines (AASMP) have been synthesized. These compounds inhibited hemozoin formation, formed complexes (KD = 12 to 20 μM) with free heme (ferriprotoporphyrin IX) at a pH close to the pH of the parasite food vacuole, and exhibited antimalarial activity in vitro. The inhibition of hemozoin formation may develop oxidative stress in Plasmodium falciparum due to the accumulation of free heme. Interestingly, AASMP developed oxidative stress in the parasite, as evident from the decreased level of glutathione and increased formation of lipid peroxide, H2O2, and hydroxyl radical (·OH) in P. falciparum. AASMP also caused mitochondrial dysfunction by decreasing mitochondrial potential (ΔΨm) in malaria parasite, as measured by both flow cytometry and fluorescence microscopy. Furthermore, the generation of ·OH may be mainly responsible for the antimalarial effect of AASMP since ·OH scavengers such as mannitol, as well as spin trap α-phenyl-n-tertbutylnitrone, significantly protected P. falciparum from AASMP-mediated growth inhibition. Cytotoxicity testing of the active compounds showed selective activity against malaria parasite with selectivity indices greater than 100. AASMP also exhibited profound antimalarial activity in vivo against chloroquine resistant P. yoelii. Thus, AASMP represents a novel class of antimalarial.

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In Vitro Activity of Riboflavin against the Human Malaria Parasite Plasmodium falciparum

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.44.1.88-96.2000 ◽

2000 ◽

Vol 44 (1) ◽

pp. 88-96 ◽

Cited By ~ 45

Author(s):

Thomas Akompong ◽

Nafisa Ghori ◽

Kasturi Haldar

Keyword(s):

Plasmodium Falciparum ◽

Malaria Parasite ◽

Antimalarial Activity ◽

Food Vacuole ◽

Host Cells ◽

Asexual Parasite ◽

Human Malaria Parasite ◽

Human Malaria ◽

Average Size

ABSTRACT The human malaria parasite Plasmodium falciparumdigests hemoglobin and polymerizes the released free heme into hemozoin. This activity occurs in an acidic organelle called the food vacuole and is essential for survival of the parasite in erythrocytes. Since acidic conditions are known to enhance the auto-oxidation of hemoglobin, we investigated whether hemoglobin ingested by the parasite was oxidized and whether the oxidation process could be a target for chemotherapy against malaria. We released parasites from their host cells and separately analyzed hemoglobin ingested by the parasites from that remaining in the erythrocytes. Isolated parasites contained elevated amounts (38.5% ± 3.5%) of oxidized hemoglobin (methemoglobin) compared to levels (0.8% ± 0.2%) found in normal, uninfected erythrocytes. Further, treatment of infected cells with the reducing agent riboflavin for 24 h decreased the parasite methemoglobin level by 55%. It also inhibited hemozoin production by 50% and decreased the average size of the food vacuole by 47%. Administration of riboflavin for 48 h resulted in a 65% decrease in food vacuole size and inhibited asexual parasite growth in cultures. High doses of riboflavin are used clinically to treat congenital methemoglobinemia without any adverse side effects. This activity, in conjunction with its impressive antimalarial activity, makes riboflavin attractive as a safe and inexpensive drug for treating malaria caused by P. falciparum.

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Novel Inhibitor of Plasmodium Histone Deacetylase That Cures P. berghei-Infected Mice

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00729-08 ◽

2009 ◽

Vol 53 (5) ◽

pp. 1727-1734 ◽

Cited By ~ 29

Author(s):

S. Agbor-Enoh ◽

C. Seudieu ◽

E. Davidson ◽

A. Dritschilo ◽

M. Jung

Keyword(s):

Histone Deacetylases ◽

Mammalian Cells ◽

Malaria Parasite ◽

Antimalarial Activity ◽

Hdac Inhibitors ◽

High Drug ◽

Lead Compounds ◽

Drug Concentrations

ABSTRACT Histone deacetylases (HDAC) are potential targets for the development of new antimalarial drugs. The growth of Plasmodium falciparum and other apicomplexans can be suppressed in the presence of potent HDAC inhibitors in vitro and in vivo; however, in vivo parasite suppression is generally incomplete or reversible after the discontinuation of drug treatment. Furthermore, most established HDAC inhibitors concurrently show broad toxicities against parasites and human cells and high drug concentrations are required for effective antimalarial activity. Here, we report on HDAC inhibitors that are potent against P. falciparum at subnanomolar concentrations and that have high selectivities; the lead compounds have mean 50% inhibitory concentrations for the killing of the malaria parasite up to 950 times lower than those for the killing of mammalian cells. These potential drugs improved survival and completely and irreversibly suppressed parasitemia in P. berghei-infected mice.

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The pupal cuticle of Drosophila: biphasic synthesis of pupal cuticle proteins in vivo and in vitro in response to 20-hydroxyecdysone.

The Journal of Cell Biology ◽

10.1083/jcb.101.1.189 ◽

1985 ◽

Vol 101 (1) ◽

pp. 189-200 ◽

Cited By ~ 65

Author(s):

J Doctor ◽

D Fristrom ◽

J W Fristrom

Keyword(s):

Molecular Weight ◽

High Molecular Weight ◽

Ultrastructural Changes ◽

Low Molecular Weight ◽

Before And After ◽

Cuticle Protein ◽

Cuticle Proteins ◽

Pupal Cuticle

We investigated the synthesis and localization of Drosophila pupal cuticle proteins by immunochemical techniques using both a complex antiserum and monoclonal antibodies. A set of low molecular weight (15,000-25,000) pupal cuticle proteins are synthesized by the imaginal disk epithelium before pupation. After pupation, synthesis of the low molecular weight proteins ceases and a set of unrelated high molecular weight proteins (40,000-82,000) are synthesized and incorporated into the pupal cuticle. Ultrastructural changes in the cuticle deposited before and after pupation correlate with the switch in cuticle protein synthesis. A similar biphasic accumulation of low and high molecular weight pupal cuticle proteins is also seen in imaginal discs cultured in vitro. The low molecular weight pupal cuticle proteins accumulate in response to a pulse of the insect steroid hormone 20-hydroxyecdysone and begin to appear 6 h after the withdrawal of the hormone from the culture medium. The high molecular weight pupal cuticle proteins accumulate later in culture; a second pulse of hormone appears to be necessary for the accumulation of two of these proteins.

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Radiolabeled r-Hirudin as a Measure of Thrombin Activity at, or within, the Rabbit Aorta Wall In Vitro and In Vivo

Thrombosis and Haemostasis ◽

10.1055/s-0038-1642467 ◽

1994 ◽

Vol 71 (04) ◽

pp. 499-506 ◽

Cited By ~ 10

Author(s):

Mark W C Hatton ◽

Bonnie Ross-Ouellet

Keyword(s):

Rabbit Aorta ◽

Balloon Injury ◽

Recombinant Hirudin ◽

Aorta Wall ◽

Thrombin Activity ◽

Before And After ◽

The Matrix

SummaryThe behavior of 125I-labeled recombinant hirudin towards the uninjured and de-endothelialized rabbit aorta wall has been studied in vitro and in vivo to determine its usefulness as an indicator of thrombin activity associated with the aorta wall. Thrombin adsorbed to either sulfopropyl-Sephadex or heparin-Sepharose bound >95% of 125I-r-hirudin and the complex remained bound to the matrix. Binding of 125I-r-hirudin to the exposed aorta subendothelium (intima-media) in vitro was increased substantially if the tissue was pre-treated with thrombin; the quantity of l25I-r-hirudin bound to the de-endothelialized intima-media (i.e. balloon-injured in vitro) correlated positively with the quantity of bound 131I-thrombin (p <0.01). Aortas balloon-injured in vivo were measured for thrombin release from, and binding of 125I-r-hirudin to, the de-endothelialized intimal surface in vitro; 125I-r-hirudin binding correlated with the amount of active thrombin released (p <0.001). Uptake of 125I-r-hirudin by the aorta wall in vivo was proportional to the uptake of 131I-fibrinogen (as an indicator of thrombin activity) before and after balloon injury. After 30 min in the circulation, specific 125I-r-hirudin binding to the uninjured and de-endo- thelialized (at 1.5 h after injury) aorta wall was equivalent to 3.4 (± 2.5) and 25.6 (±18.1) fmol of thrombin/cm2 of intima-media, respectively. Possibly, only hirudin-accessible, glycosaminoglycan-bound thrombin is measured in this way.

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Discovery of 3-Cinnamamido-N-Substituted Benzamides as Potential Antimalarial Agents

Medicinal Chemistry ◽

10.2174/1573406416666200817160708 ◽

2020 ◽

Vol 16 ◽

Author(s):

Haicheng Liu ◽

Yushi Futamura ◽

Honghai Wu ◽

Aki Ishiyama ◽

Taotao Zhang ◽

...

Keyword(s):

Mammalian Cells ◽

Antimalarial Activity ◽

In Vitro Assays ◽

Compound Library ◽

Antimalarial Agents ◽

Phenotypic Screen ◽

Ic50 Values ◽

Substituted Benzamides

Background: Malaria is one of the most devastating parasitic diseases, yet the discovery of antimalarial agents remains profoundly challenging. Very few new antimalarials have been developed in the past 50 years, while the emergence of drug-resistance continues to appear. Objective: This study focuses on the discovery, design, synthesis, and antimalarial evaluation of 3-cinnamamido-N-substituted benzamides. Method: In this study, a screening of our compound library was carried out against the multidrug-sensitive Plasmodium falciparum 3D7 strain. Derivatives of the hit were designed, synthesized and tested against P. falciparum 3D7 and the in vivo antimalarial activity of the most active compounds was evaluated using the method of Peters’ 4-day suppressive test. Results: The retrieved hit compound 1 containing a 3-cinnamamido-N-substituted benzamide skeleton showed moderate antimalarial activity (IC50 = 1.20 µM) for the first time. A series of derivatives were then synthesized through a simple four-step workflow, and half of them exhibited slightly better antimalarial effect than the precursor 1 during the subsequent in vitro assays. Additionally, compounds 11, 23, 30 and 31 displayed potent activity with IC50 values of approximately 0.1 µM, and weak cytotoxicity against mammalian cells. However, in vivo antimalarial activity is not effective which might be ascribed to the poor solubility of these compounds. Conclusion: In this study, phenotypic screen of our compound library resulted in the first report of 3-cinnamamide framework with antimalarial activity and 40 derivatives were then designed and synthesized. Subsequent structure-activity studies showed that compounds 11, 23, 30 and 31 exhibited the most potent and selective activity against P. falciparum 3D7 strain with IC50 values around 0.1 µM. Our work herein sets another example of phenotypic screen-based drug discovery, leading to potentially promising candidates of novel antimalarial agents once given further optimization.

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Stage-dependent effect of deferoxamine on growth of Plasmodium falciparum in vitro

Blood ◽

10.1182/blood.v76.6.1250.1250 ◽

1990 ◽

Vol 76 (6) ◽

pp. 1250-1255 ◽

Cited By ~ 36

Author(s):

S Whitehead ◽

TE Peto

Keyword(s):

Plasmodium Falciparum ◽

Growth Inhibition ◽

Antimalarial Activity ◽

Clinical Malaria ◽

Inhibitory Effect ◽

Parasite Development ◽

And Control ◽

Speed Of Onset

Abstract Deferoxamine (DF) has antimalarial activity that can be demonstrated in vitro and in vivo. This study is designed to examine the speed of onset and stage dependency of growth inhibition by DF and to determine whether its antimalarial activity is cytostatic or cytocidal. Growth inhibition was assessed by suppression of hypoxanthine incorporation and differences in morphologic appearance between treated and control parasites. Using synchronized in vitro cultures of Plasmodium falciparum, growth inhibition by DF was detected within a single parasite cycle. Ring and nonpigmented trophozoite stages were sensitive to the inhibitory effect of DF but cytostatic antimalarial activity was suggested by evidence of parasite recovery in later cycles. However, profound growth inhibition, with no evidence of subsequent recovery, occurred when pigmented trophozoites and early schizonts were exposed to DF. At this stage in parasite development, the activity of DF was cytocidal and furthermore, the critical period of exposure may be as short as 6 hours. These observations suggest that iron chelators may have a role in the treatment of clinical malaria.

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In vitro activities of novel catecholate siderophores against Plasmodium falciparum.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.40.9.2094 ◽

1996 ◽

Vol 40 (9) ◽

pp. 2094-2098 ◽

Cited By ~ 13

Author(s):

B Pradines ◽

F Ramiandrasoa ◽

L K Basco ◽

L Bricard ◽

G Kunesch ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Mechanism Of Action ◽

Ribonucleotide Reductase ◽

Antimalarial Activity ◽

Iron Chelators ◽

Resistant Clone ◽

Iron Deprivation ◽

Level Of Activity ◽

Susceptible Clone

The activities of novel iron chelators, alone and in combination with chloroquine, quinine, or artemether, were evaluated in vitro against susceptible and resistant clones of Plasmodium falciparum with a semimicroassay system. N4-nonyl,N1,N8-bis(2,3-dihydroxybenzoyl) spermidine hydrobromide (compound 7) demonstrated the highest level of activity: 170 nM against a chloroquine-susceptible clone and 1 microM against a chloroquine-resistant clone (50% inhibitory concentrations). Compounds 6, 8, and 10 showed antimalarial activity with 50% inhibitory concentrations of about 1 microM. Compound 7 had no effect on the activities of chloroquine, quinine, and artemether against either clone, and compound 8 did not enhance the schizontocidal action of either chloroquine or quinine against the chloroquine-resistant clone. The incubation of compound 7 with FeCI3 suppressed or decreased the in vitro antimalarial activity of compound 7, while no effect was observed with incubation of compound 7 with CuSO4 and ZnSO4. These results suggest that iron deprivation may be the main mechanism of action of compound 7 against the malarial parasites. Chelator compounds 7 and 8 primarily affected trophozoite stages, probably by influencing the activity of ribonucleotide reductase, and thus inhibiting DNA synthesis.

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Effect of ethanol and cocaine on [11C]MPC-6827 uptake in SH-SY5Y cells

Molecular Biology Reports ◽

10.1007/s11033-021-06336-7 ◽

2021 ◽

Author(s):

Naresh Damuka ◽

Miranda Orr ◽

Paul W. Czoty ◽

Jeffrey L. Weiner ◽

Thomas J. Martin ◽

...

Keyword(s):

Mechanism Of Action ◽

Ex Vivo ◽

Neuroblastoma Cells ◽

Proper Function ◽

Brain Functions ◽

Biodistribution Studies ◽

Positron Emission ◽

Vitro Binding

AbstractMicrotubules (MTs) are structural units in the cytoskeleton. In brain cells they are responsible for axonal transport, information processing, and signaling mechanisms. Proper function of these processes is critical for healthy brain functions. Alcohol and substance use disorders (AUD/SUDs) affects the function and organization of MTs in the brain, making them a potential neuroimaging marker to study the resulting impairment of overall neurobehavioral and cognitive processes. Our lab reported the first brain-penetrant MT-tracking Positron Emission Tomography (PET) ligand [11C]MPC-6827 and demonstrated its in vivo utility in rodents and non-human primates. To further explore the in vivo imaging potential of [11C]MPC-6827, we need to investigate its mechanism of action. Here, we report preliminary in vitro binding results in SH-SY5Y neuroblastoma cells exposed to ethanol (EtOH) or cocaine in combination with multiple agents that alter MT stability. EtOH and cocaine treatments increased MT stability and decreased free tubulin monomers. Our initial cell-binding assay demonstrated that [11C]MPC-6827 may have high affinity to free/unbound tubulin units. Consistent with this mechanism of action, we observed lower [11C]MPC-6827 uptake in SH-SY5Y cells after EtOH and cocaine treatments (e.g., fewer free tubulin units). We are currently performing in vivo PET imaging and ex vivo biodistribution studies in rodent and nonhuman primate models of AUD and SUDs and Alzheimer's disease.

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miR-146a-5p Promotes Chondrocyte Apoptosis and Inhibits Autophagy of Osteoarthritis by Targeting NUMB

Cartilage ◽

10.1177/19476035211023550 ◽

2021 ◽

pp. 194760352110235

Author(s):

Hongjun Zhang ◽

Wendi Zheng ◽

Du Li ◽

Jia Zheng

Keyword(s):

Caspase 3 ◽

Cartilage Tissue ◽

Luciferase Reporter ◽

Chondrocyte Apoptosis ◽

Knee Cartilage ◽

Before And After ◽

Related Proteins ◽

Human And Mouse

Objective miR-146a-5p was found to be significantly upregulated in cartilage tissue of patients with osteoarthritis (OA). NUMB was shown to be involved in the autophagy regulation process of cells. We aimed to learn whether NUMB was involved in the apoptosis or autophagy process of chondrocytes in OA and related with miR-146a-5p. Methods QRT-PCR was used to detect miR-146a-5p level in 22 OA cartilage tissues and 22 controls. The targets of miR-146a-5p were analyzed using software and the luciferase reporter experiment. The apoptosis and autophagy, and related proteins were detected in chondrocytes treated with miR-146a-5p mimic/inhibitor or pcDNA3.1-NUMB/si-NUMB and IL-1β, respectively. In vivo experiment, intra-articular injection of miR-146a-5p antagomir/NC was administered at the knee of OA male mice before and after model construction. Chondrocyte apoptosis and the expression of apoptosis and autophagy-related proteins were also detected. Results miR-146a-5p was highly expressed in knee cartilage tissue of patients with OA, while NUMB was lowly expressed and negatively regulated by miR-146a-5p. Upregulation of miR-146a-5p can promote cell apoptosis and reduce autophagy of human and mouse chondrocytes by modulating the levels of cleaved caspase-3, cleaved PARP, Bax, Beclin 1, ATG5, p62, LC3-I, and LC3-II. Increasing the low level of NUMB reversed the effects of miR-146a-5p on chondrocyte apoptosis and autophagy. Intra-articular injection of miR-146a-5p antagomir can also reverse the effects of miR-146a-5p on the apoptosis and autophagy of knee joint chondrocytes in OA mice. Conclusion Downregulation of miR-146a-5p suppresses the apoptosis and promotes autophagy of chondrocytes by targeting NUMB in vivo and in vitro.

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