ABSTRACT
FR235222 is a natural tetra-cyclopeptide with a strong inhibition effect on histone deacetylases, effective on mammalian cells as well as on intracellular apicomplexan parasites, such as Toxoplasma gondii, in the tachyzoite and bradyzoite stages. This molecule is characterized by two parts: the zinc-binding group, responsible for the binding to the histone deacetylase, and the cyclic tetrapeptide moiety, which plays a crucial role in cell permeability. Recently, we have shown that the cyclic tetrapeptide coupled with a fluorescent diethyl-amino-coumarin was able to maintain properties of cellular penetration on human cells. Here, we show that this property can be extended to the crossing of the Toxoplasma gondii cystic cell wall and the cell membrane of the parasite in its bradyzoite form, while maintaining a high efficacy as a histone deacetylase inhibitor. The investigation by molecular modeling allows a better understanding of the penetration mechanism.
Subject(s)
Coumarins/pharmacology , Fluorescent Dyes/pharmacology , Histone Deacetylase Inhibitors/pharmacology , Histone Deacetylases/metabolism , Peptides, Cyclic/pharmacology , Coumarins/chemistry , Fluorescent Dyes/chemistry , Histone Deacetylase Inhibitors/chemistry , Models, Molecular , Peptides, Cyclic/chemistry , Toxoplasma/cytology , Toxoplasma/enzymologyABSTRACT
Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen naturally resistant to many common antibiotics and acquires new resistance traits at an alarming pace. Targeting the bacterial virulence factors by an antivirulence strategy, therefore, represents a promising alternative approach besides antibiotic therapy. The Type III secretion system (T3SS) of P. aeruginosa is one of its main virulence factors. It consists of more than 20 proteins building a complex syringe-like machinery enabling the injection of toxin into host cells. Previous works showed that disrupting interactions between components of this machinery efficiently lowers the bacterial virulence. Using automated target-based screening of commercial and in-house libraries of small molecules, we identified compounds inhibiting the protein-protein interaction between PscE and PscG, the two cognate chaperones of the needle subunit PscF of P. aeruginosa T3SS. Two hits were selected and assembled using Split/Mix/Click chemistry to build larger hybrid analogues. Their efficacy and toxicity were evaluated using phenotypic analysis including automated microscopy and image analysis. Two nontoxic hybrid leads specifically inhibited the T3SS and reduced the ex vivo cytotoxicity of bacteria and their virulence in Galleria mellonella.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Proteins/metabolism , Pseudomonas Infections/microbiology , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/pathogenicity , Type III Secretion Systems/metabolism , Animals , Anti-Bacterial Agents/chemistry , Bacterial Proteins/genetics , Disease Models, Animal , Humans , Moths , Protein Binding/drug effects , Pseudomonas aeruginosa/genetics , Pseudomonas aeruginosa/metabolism , Type III Secretion Systems/genetics , Virulence/drug effectsABSTRACT
A small uncharged cyclopeptide scaffold inspired by a natural product and designed to undergo postfunctionalizations was used as a new transmembrane vector. A bioactive and fluorescent triazole aminocoumarin was bound to this carrier to facilitate its moving across cell and subcellular membranes, and this led to an increase in its cell toxicity.
Subject(s)
Peptides, Cyclic/chemistry , Cell Membrane , Molecular StructureABSTRACT
Synthetic 3-alkylpyridine marine alkaloid (3-APA) analogues have shown good antimalarial activity against Plasmodium falciparum. However, despite their structural originality, their molecular target was unknown. Herein, we report a proposal for the antimalarial mechanism of action of 3-APA analogues through interference with the process of hemozoin (Hz) formation. The interaction between 3-APA analogues and heme groups was investigated employing an in silico approach and biophysical techniques such as ultraviolet-visible light (UV-vis) titration and electrospray ionization-mass spectrometry (ESI-MS). The in silico approach was performed based on pure ab initio electronic structure methods in order to obtain insights at the molecular level concerning the binding process of antimalarial drugs at their target site, the heme group. In silico results showed that the formation of heme:3-APA complexes at a molecular ratio of 2:1 are more stable than 1:1 complexes. These results were further confirmed by experimental techniques, such as UV-vis and high-resolution mass spectrometry (ESI-TOF), for two of the most active 3-APA analogues.
Subject(s)
Alkaloids/chemistry , Antimalarials/chemistry , Heme/metabolism , Marine Biology , Pyridines/chemistry , Binding SitesABSTRACT
A modular approach to synthesize anti-Apicomplexa parasite inhibitors was developed that takes advantage of a pluripotent cyclic tetrapeptide scaffold capable of adjusting appendage and skeletal diversities in only a few steps (one to three steps). The diversification processes make use of selective radical coupling reactions and involve a new example of a reductive carbon-nitrogen cleavage reaction with SmI2. The resulting bioactive cyclic peptides have revealed new insights into structural factors that govern selectivity between Apicomplexa parasites such as Toxoplasma and Plasmodium and human cells.
Subject(s)
Apicomplexa/chemistry , Peptides, Cyclic/chemical synthesis , Plasmodium/chemistry , Toxoplasma/chemistry , Host-Parasite Interactions , Humans , Peptides, Cyclic/chemistryABSTRACT
A Th-symmetrical C60 hexakis-adduct bearing 12 peripheral azide groups has been prepared and used to produce functionalized derivatives by the copper mediated Huisgen 1,3-dipolar cycloaddition of azides and alkynes.