Search results for "combinatorial"

Organic derivatives of mercury and tin as promoters of membrane lipid peroxidation.

2008

The toxicity mechanisms of mercury and tin organic derivatives are still under debate. Generally the presence of organic moieties in their molecules makes these compounds lipophilic and membrane active species. The recent results suggest that Hg and Sn compounds deplete HS-groups in proteins, glutathione and glutathione-dependent enzymatic systems; this process also results in the production of reactive oxygen species (ROS), the enhancement of membrane lipids peroxidation and damage of the antioxidative defence system. The goal of this review is to present recent results in the studies oriented towards the role of organomercury and organotin compounds in the xenobiotic-mediated enhancement …

Polysarcosine-containing copolymers: Synthesis, characterization, self-assembly, and applications

2018

Although the first polysarcosine (pSar) synthesis by Wesseley et al. was reported almost a century ago, it was only recently that pSar gained broader attention and is considered a potential alternative of poly(ethylene glycol) (PEG). In contrast to polyethers, such as PEG, pSar is a polypeptoid based on the amino acid sarcosine, i.e. N-methylated glycine. As a polymer, pSar combines PEG-like properties, e.g., excellent solubility in water, protein resistance, low cellular toxicity and a non-immunogenic character, while being based on endogenous material. Sarcosine can be obtained in a simple one-step reaction of bromoacetic acid and methylamine, easily transferred into the sarcosine N-(thio…

Synthesis and characterization of bisalkylated polysarcosine-based lipopolymers

2019

The use of PEGylated lipids for the synthesis of stealth liposomes and lipid formulations for nucleic acid delivery has promoted the development of nanoparticle based drugs for cancer therapy, and chronic diseases. Moreover, several other nanomedicines based on these materials have advanced into clinical trails. This enormous success, however, has recently been compromised by the occurrence of immune responses towards PEG, which render pharmacokinetics and can substantially reduce the therapeutic efficiency of drugs. Therefore, alternatives for PEGylated lipids with comparable or even identical solution properties are required. In this work, we report the synthesis of polysarcosine based li…

Iron‐Catalyzed C( sp 2 )−C( sp 3 ) Cross‐Coupling of Chlorobenzamides with Alkyl Grignard Reagents: Development of Catalyst System, Synthetic Scope, …

2018

Cyclic Analogs of Desferrioxamine E Siderophore for 68Ga Nuclear Imaging: Coordination Chemistry and Biological Activity in Staphylococcus aureus

2021

As multidrug-resistant bacteria are an emerging problem and threat to humanity, novel strategies for treatment and diagnostics are actively sought. We aim to utilize siderophores, iron-specific strong chelating agents produced by microbes, as gallium ion carriers for diagnosis, applying that Fe(III) can be successfully replaced by Ga(III) without losing biological properties of the investigated complex, which allows molecular imaging by positron emission tomography (PET). Here, we report synthesis, full solution chemistry, thermodynamic characterization, and the preliminary biological evaluation of biomimetic derivatives (FOX) of desferrioxamine E (FOXE) siderophore, radiolabeled with 68Ga …

Chemical Synthesis of 2′-O-Alkylated siRNAs

2010

Chemical synthesis has been a major endeavor to create active siRNAs. The downregulation of mRNA by 21-mer double-stranded siRNAs can be improved by using modified nucleotides, especially 2'-O-alkylated ones. Besides the commercially available 2 cent-O-methyl ribosides, 2'-alkyl groups bearing positive charges are especially promising candidates. We have shown that in a proper formulation they are superior to unmodified siRNAs. This may be due to enhanced stability and most probably to a better uptake into the cells.

Stereoselective Combinatorial Ugi-Multicomponent Synthesis on Solid Phase

2000

Solvent-free ruthenium-catalysed triflate coupling as a convenient method for selective azole-o-C-H monoarylation.

2019

Metal-catalysed ortho-directed C–H functionalization usually faces selectivity issues in the competition between mono- and disubstitution processes. We report herein the ruthenium-catalysed N-directed C–H monoarylation of arylpyrazoles with a selectivity of up to 96% or that generally reaches values above 80%. This selectivity is an effect of solvent-free conditions associated with sulfonate reagents, in the absence of frequently used acidic additives.

Mesoporous Materials Incorporating Metal Triflates

2016

Metal triflates attracted a large interest as catalysts in the past three decades especially due to the Lewis acid properties exhibited by these compounds and the variety of the functional group transformations. This chapter proposes an overview presenting the catalytic performances of triflates both as molecular compounds and as triflates dispersed in different solid matrices. In the first part the performances of molecular triflates in organic reactions carried out in the presence of water or water as solvent considering both water-sensitive and -insensitive metals are discussed. Then, the importance of materials incorporating triflates is demonstrated for catalysts obtained via immobiliz…

d-Glucose as a multivalent chiral scaffold for combinatorial chemistry

2002

Due to their high density of functional groups and their availability in a variety of diastereomeric forms, monosaccharides are considered attractive scaffolds for combinatorial chemistry that allow the attachment and defined spatial alignment of up to five different pharmacophoric groups. For their application in combinatorial syntheses on solid phase, a set of selectively removable hydroxy protecting groups in combination with a cleavable anchor is required. Herein, we report on the construction and use of a versatile multivalent glucose building block for parallel synthesis on the solid phase.