Two new thiocarboxylic acids, p-bromothiobenzoic BTA and thionaphthoic acid TNA, and five new hom... more Two new thiocarboxylic acids, p-bromothiobenzoic BTA and thionaphthoic acid TNA, and five new homo- and heteroleptic bismuth(iii) compounds derived from thiocarboxylic acids: [Bi{S(C=O)C6H4Br}3] 1, [PhBi{S(C=O)C6H4Br}2] 2, [Bi{S(C=O)C10H7}3] 3, [PhBi{S(C=O)C10H7}2] 4, and [Ph2Bi{S(C=O)C10H7}] 5 were synthesised and fully characterised. The solid-state structure of complex [PhBi{S(C=O)C6H4Br}2] 2 was confirmed by X-ray crystallography. In complex 2, the two thiocarboxylate ligands are coordinated to the bismuth(iii) centre in a didentate fashion, forming a distorted octahedral geometry in which the phenyl group and the lone pair are oriented axial to the plane formed by the two thiocarboxylate ligands. Long-range Bi–S interactions (3.54 Å) link these monomeric units to form a one-dimensional polymer. These compounds, in addition to six previously synthesised complexes: [Bi{SC(=O)C6H5}3] 6, [PhBi{SC(=O)C6H5}2] 7, [Ph2Bi{SC(=O)C6H5}] 8, [Bi{SC(=O)C6H4NO2}3] 9, [PhBi{SC(=O)C6H4NO2}2] 10, and [PhBi{SC(=O)C6H4SO3}] 11, and the thiocarboxylic acids themselves, were assessed for their in vitro activity against Leishmania major promastigotes, and for general toxicity against human fibroblast cells. The thiocarboxylic acids, with the exception of thiobenzoic acid and sulfothiobenzoic acid, were toxic to both L. major parasites and the mammalian cells at high concentrations of 50–100 μM. The bismuth(iii) thiocarboxylate derivatives proved to be more active than the corresponding acids. Among these, the heteroleptic phenyl-substituted bismuth(iii) complexes 2, 4, 5, and 7 were highly active, showing IC50 (half maximal inhibitory concentration) values ranging from 0.39 to 4.69 μM, and a clear ligand dependence on activity.
Related Article: Yih Ching Ong, Victoria L. Blair, Lukasz Kedzierski, Philip C. Andrews|2014|Dalt... more Related Article: Yih Ching Ong, Victoria L. Blair, Lukasz Kedzierski, Philip C. Andrews|2014|Dalton Trans.|43|12904|doi:10.1039/C4DT00957F
Plasmodium yoelii merozoite surface protein 4/5 (PyMSP4/5), expressed as a recombinant protein, w... more Plasmodium yoelii merozoite surface protein 4/5 (PyMSP4/5), expressed as a recombinant protein, was highly effective at protecting mice against lethal challenge with P. yoelii. There was a significant correlation between prechallenge antibody levels and peak parasitemia, suggesting that the homologues of PyMSP4/5 in Plasmodium falciparum are promising components of a subunit vaccine against malaria.
Immune responses induced to DNA vaccination vary considerably and depend on a variety of factors,... more Immune responses induced to DNA vaccination vary considerably and depend on a variety of factors, including the physical form in which the antigen is expressed by target cells and presented to the immune system. Data on the effect of these factors will aid improved design of DNA vaccines and facilitate their further development. We examined the effect of different forms of surface anchoring on the immunogenicity of a DNA vaccine. A number of constructs were generated encoding Plasmodium yoelii merozoite surface protein 4/5 (PyMSP4/5) with or without its C-terminal glycosylphosphatidylinositol (GPI) attachment signal, replacing the endogenous GPI signal of PyMSP4/5 with that of mouse decay-accelerating factor (DAF), a well-established model for GPI-anchoring in mammalian cells, or the transmembrane anchor and cytoplasmic tail of mouse tissue factor (TF). All constructs were demonstrated to express the full-length PyMSP4/5 in transfected COS cells and induce PyMSP4/5-specific antibodies in mice. The GPI attachment signal of PyMSP4/5 was found to function poorly in mammalian cells and result in a much lower level of PyMSP4/5 expression in vitro than its mammalian counterpart. The DNA vaccine containing the mammalian GPI attachment signal induced the highest levels of antibodies and impacted Ig isotype distribution, consistent with the presence of a CD1-restricted pathway of Ig formation to GPI-anchored membrane proteins. Despite the induction of specific antibodies, none of these DNA vaccines induced sufficient levels of antibodies to protect mice against a lethal challenge with P. yoelii.
Leishmania are protozoan parasites responsible for a spectrum of diseases collectively known as l... more Leishmania are protozoan parasites responsible for a spectrum of diseases collectively known as leishmaniasis. The disease is a significant health problem in many regions of the world and emerges as a serious co-infection in HIV-positive individuals. Current treatment of the disease is based on a limited number of chemotherapeutic agents which are rapidly becoming ineffective, and are characterized by high toxicity and cost. This review focuses on recent advances in antileishmanial drug development and improvements to current treatment options. Novel approaches currently used to identify leishmanicidal compounds as diverse as antimicrobial peptides and natural plant extracts are described in this review.
Two new thiocarboxylic acids, p-bromothiobenzoic BTA and thionaphthoic acid TNA, and five new hom... more Two new thiocarboxylic acids, p-bromothiobenzoic BTA and thionaphthoic acid TNA, and five new homo- and heteroleptic bismuth(iii) compounds derived from thiocarboxylic acids: [Bi{S(C=O)C6H4Br}3] 1, [PhBi{S(C=O)C6H4Br}2] 2, [Bi{S(C=O)C10H7}3] 3, [PhBi{S(C=O)C10H7}2] 4, and [Ph2Bi{S(C=O)C10H7}] 5 were synthesised and fully characterised. The solid-state structure of complex [PhBi{S(C=O)C6H4Br}2] 2 was confirmed by X-ray crystallography. In complex 2, the two thiocarboxylate ligands are coordinated to the bismuth(iii) centre in a didentate fashion, forming a distorted octahedral geometry in which the phenyl group and the lone pair are oriented axial to the plane formed by the two thiocarboxylate ligands. Long-range Bi–S interactions (3.54 Å) link these monomeric units to form a one-dimensional polymer. These compounds, in addition to six previously synthesised complexes: [Bi{SC(=O)C6H5}3] 6, [PhBi{SC(=O)C6H5}2] 7, [Ph2Bi{SC(=O)C6H5}] 8, [Bi{SC(=O)C6H4NO2}3] 9, [PhBi{SC(=O)C6H4NO2}2] 10, and [PhBi{SC(=O)C6H4SO3}] 11, and the thiocarboxylic acids themselves, were assessed for their in vitro activity against Leishmania major promastigotes, and for general toxicity against human fibroblast cells. The thiocarboxylic acids, with the exception of thiobenzoic acid and sulfothiobenzoic acid, were toxic to both L. major parasites and the mammalian cells at high concentrations of 50–100 μM. The bismuth(iii) thiocarboxylate derivatives proved to be more active than the corresponding acids. Among these, the heteroleptic phenyl-substituted bismuth(iii) complexes 2, 4, 5, and 7 were highly active, showing IC50 (half maximal inhibitory concentration) values ranging from 0.39 to 4.69 μM, and a clear ligand dependence on activity.
Related Article: Yih Ching Ong, Victoria L. Blair, Lukasz Kedzierski, Philip C. Andrews|2014|Dalt... more Related Article: Yih Ching Ong, Victoria L. Blair, Lukasz Kedzierski, Philip C. Andrews|2014|Dalton Trans.|43|12904|doi:10.1039/C4DT00957F
Plasmodium yoelii merozoite surface protein 4/5 (PyMSP4/5), expressed as a recombinant protein, w... more Plasmodium yoelii merozoite surface protein 4/5 (PyMSP4/5), expressed as a recombinant protein, was highly effective at protecting mice against lethal challenge with P. yoelii. There was a significant correlation between prechallenge antibody levels and peak parasitemia, suggesting that the homologues of PyMSP4/5 in Plasmodium falciparum are promising components of a subunit vaccine against malaria.
Immune responses induced to DNA vaccination vary considerably and depend on a variety of factors,... more Immune responses induced to DNA vaccination vary considerably and depend on a variety of factors, including the physical form in which the antigen is expressed by target cells and presented to the immune system. Data on the effect of these factors will aid improved design of DNA vaccines and facilitate their further development. We examined the effect of different forms of surface anchoring on the immunogenicity of a DNA vaccine. A number of constructs were generated encoding Plasmodium yoelii merozoite surface protein 4/5 (PyMSP4/5) with or without its C-terminal glycosylphosphatidylinositol (GPI) attachment signal, replacing the endogenous GPI signal of PyMSP4/5 with that of mouse decay-accelerating factor (DAF), a well-established model for GPI-anchoring in mammalian cells, or the transmembrane anchor and cytoplasmic tail of mouse tissue factor (TF). All constructs were demonstrated to express the full-length PyMSP4/5 in transfected COS cells and induce PyMSP4/5-specific antibodies in mice. The GPI attachment signal of PyMSP4/5 was found to function poorly in mammalian cells and result in a much lower level of PyMSP4/5 expression in vitro than its mammalian counterpart. The DNA vaccine containing the mammalian GPI attachment signal induced the highest levels of antibodies and impacted Ig isotype distribution, consistent with the presence of a CD1-restricted pathway of Ig formation to GPI-anchored membrane proteins. Despite the induction of specific antibodies, none of these DNA vaccines induced sufficient levels of antibodies to protect mice against a lethal challenge with P. yoelii.
Leishmania are protozoan parasites responsible for a spectrum of diseases collectively known as l... more Leishmania are protozoan parasites responsible for a spectrum of diseases collectively known as leishmaniasis. The disease is a significant health problem in many regions of the world and emerges as a serious co-infection in HIV-positive individuals. Current treatment of the disease is based on a limited number of chemotherapeutic agents which are rapidly becoming ineffective, and are characterized by high toxicity and cost. This review focuses on recent advances in antileishmanial drug development and improvements to current treatment options. Novel approaches currently used to identify leishmanicidal compounds as diverse as antimicrobial peptides and natural plant extracts are described in this review.
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