Plasmodium falciparum

The absence of a vaccine and the rampant resistance to almost all antimalarial drugs have accentuated the urgent need for new antimalarial drugs and drug targets for both prophylaxis and chemotherapy. The aim of the study was to discover effective plant extracts against Plasmodium falciparum. In the present study, the hexane, chloroform, ethyl acetate, acetone, and methanol extracts of Citrus sinensis (peel), Leucas aspera, Ocimum sanctum, Phyllanthus acidus (leaf), Terminalia chebula (seed) were tested for their antimalarial activity against chloroquine (CQ)-sensitive (3D7) strain of P.

OBJECTIVE: To evaluate the in vitro and in vivo antiplasmodial activity and the cytotoxicity of Phyllanthus emblica Linn, Terminalia chebula Retz, and Terminalia bellerica (Gaertn) Roxb extracts. MATERIAL AND METHOD: Standard phytochemical screening tests were used to detect metabolites in the plant extract. The water extracts of medicinal plants were tested for their antiplasmodial activity in vitro by assessing their ability to inhibit the uptake of [3H] hypoxanthine into the Plasmodium falciparum K1 multidrug-resistant strain.

Antibodies (Abs) are critical for immunity to malaria. However, Plasmodium falciparum specific Abs decline rapidly in absence of reinfection, suggesting impaired immunological memory. This study determines whether residents of Sweden that were treated for malaria following international travel maintained long-lasting malaria-specific Abs and memory B cells (MBCs).

A new generation of strategies is evolving that aim to block malaria transmission by employing genetically modified vectors or mosquito pathogens or symbionts that express anti-parasite molecules. Whilst transgenic technologies have advanced rapidly, there is still a paucity of effector molecules with potent anti-malaria activity whose expression does not cause detrimental effects on mosquito fitness. Our objective was to examine a wide range of antimicrobial peptides (AMPs) for their toxic effects on Plasmodium and anopheline mosquitoes.

The outcome of the Phase IIb trial of RTS,S (a vaccine comprising the polypeptides RTS and S) in young Mozambican children consolidated hopes that effective vaccination against malaria is a step nearer, and even elicited a generous promise of commitment from the Chancellor of the Exchequer of the UK. However, it seems that both optimism and generosity should be moderated by the failure of this vaccine to induce meaningful protection against infection by Plasmodium falciparum and that we should await confirmation of its efficacy in diminishing the incidence of severe malaria.

Eleven Thai isolates and one West African isolate of Plasmodium falciparum were tested for their susceptibility to the Chinese antimalarial drugs artemisinine (qinghaosu) and artemether. The isolates were cultivated by the Trager-Jensen candle-jar technique and exposed to the action of the drugs for 36-48 hours. Artemisinine inhibited growth of most isolates at 10(-7)-10(-8) mol/litre and artemether at 10(-8) mol/litre (with an initial parasitaemia of 0.5-1.0%).

With the current increase of international travel and increasing drug resistance, United Kingdom residents stand a high risk of contracting malaria when they visit endemic countries. The development of anti-malarial agents from old traditional plant remedies to modern synthetic drugs is briefly reviewed. Resistance to the latter has spread rapidly since the 1950s, culminating in the widespread distribution of multiple drug-resistant strains of Plasmodium falciparum in most endemic areas.

Plasmodium falciparum infecting hemoglobin (Hb) H and/or Hb Constant Spring erythrocytes in vitro was relatively more resistant than that infecting normal erythrocytes to artesunate and chloroquine, while the sensitivity to pyrimethamine was unchanged. The 50% inhibitory concentrations (IC50) for artesunate in HbH (alpha-thal 1/alpha-thal 2), HbH (alpha-thal 1/Hb Constant Spring), and homozygous Hb Constant Spring erythrocytes were 4.5 +/- 2.8, 8.5 +/- 3.2, and 2.6 +/- 1.6 nM compared with 0.82 +/- 0.35 nM in normal erythrocytes (P less than 0.002 for all three cases).

The vast majority of the 1-2 million malaria associated deaths that occur each year are due to anemia and cerebral malaria (the attachment of erythrocytes containing mature forms of Plasmodium falciparum to the endothelial cells that line the vascular beds of the brain). A "model system" for the study of cerebral malaria employs amelanotic melanoma cells as the "target" cells in an in vitro cytoadherence assay.

Artemisinin is an important new antimalarial agent containing a bridged endoperoxide. The in vitro antimalarial activity of an artemisinin derivative, arteether, is antagonized by two iron chelators, pyridoxal benzoylhydrazone and 1,2-dimethyl-3-hydroxypyrid-4-one. Similarly, the acute toxicity of artemisinin in mice is antagonized by another chelator, deferoxamine-hydroxyethylstarch. A combination of artemisinin and hemin oxidizes erythrocyte membrane thiols in vitro, and this oxidation is also inhibited by an iron chelator.