Synthetic strategies for efficient conjugation of organometallic complexes with pendant protein reactive markers

Synthetic Approaches of Epoxysuccinate Chemical Probes

Synthetic chemical probes are powerful tools for investigating biological processes. They are particularly useful for proteomic studies such as activity-based protein profiling (ABPP). These chemical methods initially used mimics of natural substrates. As the techniques gained prominence, more and more elaborate chemical probes with increased specificity towards given enzyme/protein families and amenability to various reaction conditions were used. Among the chemical probes, peptidyl-epoxysuccinates represent one of the first types of compounds used to investigate the activity of the cysteine protease papain-like family of enzymes. Structurally derived from the natural substrate, a wide body of inhibitors and activity- or affinity-based probes bearing the electrophilic oxirane unit for covalent labeling of active enzymes now exists. Herein, we review the literature regarding the synthetic approaches to epoxysuccinate-based chemical probes together with their reported applications, from biological chemistry and inhibition studies to supramolecular chemistry and the formation of protein arrays.

Recent advances in biological activities of rhodium complexes: Their applications in drug discovery research

Unique structure, characteristic reactivity, and facile synthesis of metal complexes have made them efficient ligands in drug development research. Among them, rhodium complexes have a limited history and there are a few discussions about their biological activities documented in the literature. However, investigation of kinetically inert rhodium complexes has recently attracted lots of attention and especially there are various evidences on their anti-cancer activity. It seems that they can be investigated as a versatile surrogates or candidates for the existing drugs which do not affect selectively or suffer from various side effects. In recent years, there has been an increasing interest in the use of mononuclear rhodium (III) organometallo drugs due to its versatile structurally important aspects to inhibit various enzymes. It has been demonstrated that organometallic Rh complexes profiting from both organic and inorganic aspects have shown more potent biological activities than classical inorganic compartments. In this respect, smart design, use of the appropriate organic ligands, and efficient and user-friendly synthesis of organometallic Rh complexes have played crucial roles in the inducing desirable biological activities. In this review, we focused on the recent advances published on the bioactivity of Rh (III/II/I) complexes especially inhibitory activity, from 2013 till now. Accordingly, considering the structure-activity relationship (SAR), the effect of oxidation state (+1, +2, and +3) and geometry (dimer or monomer complexes with coordination number of 4 and 6) of Rh complexes as well as various ligands on in vitro and in vivo studies was comprehensively discussed.

Cyclic Alkenylsulfonyl Fluorides: Palladium-Catalyzed Synthesis and Functionalization of Compact Multifunctional Reagents

A series of low‐molecular‐weight, compact, and multifunctional cyclic alkenylsulfonyl fluorides were efficiently prepared from the corresponding alkenyl triflates. Palladium‐catalyzed sulfur dioxide insertion using the surrogate reagent DABSO effects sulfinate formation, before trapping with an F electrophile delivers the sulfonyl fluorides. A broad range of functional groups are tolerated, and a correspondingly large collection of derivatization reactions are possible on the products, including substitution at sulfur, conjugate addition, and N‐functionalization. Together, these attributes suggest that this method could find new applications in chemical biology.

Near-Infrared Intraoperative Chemiluminescence Imaging

Intraoperative imaging technologies recently entered the operating room, and their implementation is revolutionizing how physicians plan, monitor, and perform surgical interventions. In this work, we present a novel surgical imaging reporter system: intraoperative chemiluminescence imaging (ICI). To this end, we have leveraged the ability of a chemiluminescent metal complex to generate near-infrared light upon exposure to an aqueous solution of Ce(4+) in the presence of reducing tissue or blood components. An optical camera spatially resolves the resulting photon flux. We describe the construction and application of a prototype imaging setup, which achieves a detection limit as low as 6.9 pmol cm(-2) of the transition-metal-based ICI agent. As a proof of concept, we use ICI for the in vivo detection of our transition metal tracer following both systemic and subdermal injections. The very high signal-to-noise ratios make ICI an interesting candidate for the development of new intraoperative imaging technologies.

Using Hydrazine to Link Ferrocene with Re(CO)3: A Modular Approach

Acetyl ferrocene and diacetyl ferrocene both readily react with an excess of hydrazine to afford the corresponding hydrazone compounds. These compounds can then be linked to Re(CO)₃ via a metal-mediated Schiff base reaction, resulting in a series of ferrocene-Re(CO)₃ conjugates with different stoichiometries. Conjugates with 1:1, 1:2, and 2:1 ferrocene: Re(CO)₃ ratios can be produced via this "modular" type synthesis approach. Several examples of these conjugates were structurally characterized, and their spectroscopic, electrochemical, and spectroelectrochemical behaviors were investigated. The electronic structures of these compounds were also probed using DFT and TDDFT calculations.