Identification of potent α-amylase inhibitors via dynamic combinatorial chemistry

In this study, we report for the first time the discovery of potent α-amylase inhibitors using principle of dynamic combinatorial chemistry. The best compound identified exhibited not only high inhibitory efficiency but also low cytotoxicity. The binding mode and possible mechanism are determined in the subsequent kinetic and molecular docking studies.

Multivalent butyrylcholinesterase inhibitor discovered by exploiting dynamic combinatorial chemistry

In this study, we report the generation of a polymer-based dynamic combinatorial library (DCL) incorporating exchangeable side chains using acylhydrazone formation reaction. In combination with tetrameric butyrylcholinesterase (BChE), the most potent binding side chain was identified, and the information obtained was further used for the synthesis of a multivalent BChE inhibitor. In the in vitro biological evaluation, this multivalent inhibitor exhibited not only better inhibitory effect than the commercial reference but also high selectivity on BChE over acetylcholinesterase (AChE).

Development of a multivalent acetylcholinesterase inhibitor via dynamic combinatorial chemistry

In this study, we report the generation of a polymer based dynamic combinatorial library (DCL) using aldehyde-functionalized linear poly(glycidol) and hydrazide derivatives as initial building blocks. In combination with tetrameric acetylcholinesterase (AChE), a certain type of amplified acylhydrazone side chain is identified and further used for the synthesis of a multivalent AChE inhibitor. The cytotoxicity and inhibition properties of the multivalent inhibitor are evaluated, and the results indicate superior bioactivity compared to the commercial reference Edrophonium chloride.

Engineering multilayer chemical networks

Dynamic multilevel systems emerged in the last few years as new platforms to study thermodynamic systems. In this work, unprecedented fully communicated three-level systems are studied. First, different conditions were screened to selectively activate thiol/dithioacetal, thiol/thioester, and thiol/disulfide exchanges, individually or in pairs. Some of those conditions were applied, sequentially, to build multilayer dynamic systems wherein information, in the form of relative amounts of building blocks, can be directionally transmitted between different exchange pools. As far as we know, this is the first report of one synthetic dynamic chemical system where relationships between layers can be changed through network operations.

Nano-Assembly of Pamitoyl-Bioconjugated Coenzyme-A for Combinatorial Chemo-Biologics in Transcriptional Therapy

Pathogenesis, the biological mechanism that leads to the diseased state, of many cancers is driven by interruptions to the role of Myc oncoprotein, a regulator protein that codes for a transcription factor. One of the most significant biological interruptions to Myc protein is noted as its dimerization with Max protein, another important factor of family of transcription factors. Binding of this heterodimer to E-Boxes, enhancer boxes as DNA response element found in some eukaryotes that act as a protein-binding site and have been found to regulate gene expression, are interrupted to regulate cancer pathogenesis. The systemic effectiveness of potent small molecule inhibitors of Myc-Max dimerization has been limited by poor bioavailability, rapid metabolism, and inadequate target site penetration. The potential of gene therapy for targeting Myc can be fully realized by successful synthesis of a smart cargo. We developed a "nuclein" type nanoparticle "siNozyme" (45 ± 5 nm) from nanoassembly of pamitoyl-bioconjugated acetyl coenzyme-A for stable incorporation of chemotherapeutics and biologics to achieve remarkable growth inhibition of human melanoma. Results indicated that targeting transcriptional gene cMyc with siRNA with codelivery of a topoisomerase inhibitor, amonafide caused ∼90% growth inhibition and 95% protein inhibition.

Resolving a Reactive Organometallic Intermediate from Dynamic Directing Group Systems by Selective C-H Activation

Catalyst discovery from systems of potential precursors is a challenging endeavor. Herein, a new strategy applying dynamic chemistry to the identification of catalyst precursors from C-H activation of imines is proposed and evaluated. Using hydroacylation of imines as a model reaction, the selection of an organometallic reactive intermediate from a dynamic imine system, involving many potential directing group/metal entities, is demonstrated. The identity of the amplified reaction intermediate with the best directing group could be resolved in situ by ESI-MS, and coupling of the procedure to an iterative deconvolution protocol generated a system with high screening efficiency.

Target-directed Dynamic Combinatorial Chemistry: A Study on Potentials and Pitfalls as Exemplified on a Bacterial Target

Target-directed dynamic combinatorial chemistry (DCC) is an emerging technique for the efficient identification of inhibitors of pharmacologically relevant targets. In this contribution, we present an application for a bacterial target, the lectin FimH, a crucial virulence factor of uropathogenic E. coli being the main cause of urinary tract infections. A small dynamic library of acylhydrazones was formed from aldehydes and hydrazides and equilibrated at neutral pH in presence of aniline as nucleophilic catalyst. The major success factors turned out to be an accordingly adjusted ratio of scaffolds and fragments, an adequate sample preparation prior to HPLC analysis, and the data processing. Only then did the ranking of the dynamic library constituents correlate well with affinity data. Furthermore, as a support of DCC applications especially to larger libraries, a new protocol for improved hit identification was established.

Enzyme classification using complex dynamic hemithioacetal systems

A complex dynamic hemithioacetal system was used in combination with pattern recognition methodology to classify lipases into distinct groups.

A complex dynamic hemithioacetal system was generated for the evaluation of lipase reactivities in organic media. In combination with pattern recognition methodology, twelve different lipases were successfully classified into four distinct groups following their reaction selectivities and reactivities. A probe lipase was further categorized using the training matrix with predicted reactivity.

Dynamic combinatorial/covalent chemistry: a tool to read, generate and modulate the bioactivity of compounds and compound mixtures

Reversible covalent bond formation under thermodynamic control adds reactivity to self-assembled supramolecular systems, and is therefore an ideal tool to assess complexity of chemical and biological systems. Dynamic combinatorial/covalent chemistry (DCC) has been used to read structural information by selectively assembling receptors with the optimum molecular fit around a given template from a mixture of reversibly reacting building blocks. This technique allows access to efficient sensing devices and the generation of new biomolecules, such as small molecule receptor binders for drug discovery, but also larger biomimetic polymers and macromolecules with particular three-dimensional structural architectures. Adding a kinetic factor to a thermodynamically controlled equilibrium results in dynamic resolution and in self-sorting and self-replicating systems, all of which are of major importance in biological systems. Furthermore, the temporary modification of bioactive compounds by reversible combinatorial/covalent derivatisation allows control of their release and facilitates their transport across amphiphilic self-assembled systems such as artificial membranes or cell walls. The goal of this review is to give a conceptual overview of how the impact of DCC on supramolecular assemblies at different levels can allow us to understand, predict and modulate the complexity of biological systems.

Thiazolidinones derived from dynamic systemic resolution of complex reversible-reaction networks

A complex dynamic system based on a network of multiple reversible reactions has been established. The network was applied to a dynamic systemic resolution protocol based on kinetically controlled lipase-catalyzed transformations. This resulted in the formation of cyclized products, where two thiazolidinone compounds were efficiently produced from a range of potential transformations.

Silver-catalyzed dynamic systemic resolution of α-iminonitriles in a 1,3-dipolar cycloaddition process

A silver-catalyzed dynamic azomethine ylide system was kinetically resolved in a tandem cycloaddition process, yielding an exclusive pyrrolidine product.