Combinatorial Chemistry & High Throughput Screening - Volume 17, Issue 6, 2014

A comparative structure-affinity study of anthraquinone dyes adsorption on cellulose fibre is presented in this paper. We used receptor-dependent 4D-QSAR methods based on grid and neural (SOM) methodology coupled with IVEPLS procedure. The applied RD 4D-QSAR approach focuses mainly on the ability of mapping dye properties to verify the concept of tinctophore in dye chemistry. Moreover, the stochastic SMV procedure to investigate the predictive ability of the method for a large population of 4D-QSAR models was employed. The obtained findings were compared with the previously published RI 3D/4D-QSAR models for the corresponding anthraquinone trainings sets. The neutral (protonated) and anionic (deprotonated) forms of anthraquinone scaffold were examined in order to deal with the uncertainty of the dye ionization state. The results are comparable to both the neutral and anionic dye sets regardless of the occupancy and charge descriptors applied, respectively. It is worth noting that the SOM-4D-QSAR behaves comparably to the cubic counterpart which is observed in each training/test subset specification (4D-QSAR-Jo vs SOM- 4D-QSARo and 4D-QSAR-Jq vs SOM-4D-QSARq). Additionally, an attempt was made to specify a common set of variables contributing significantly to dye-fiber binding affinity; it was simultaneously performed for some arbitrary chosen SMV models. The presented RD 4D-QSAR methodology together with IVE-PLS procedure provides a robust and predictive modeling technique, which facilitates detailed specification of the molecular motifs significantly contributing to the fiber-dye affinity.

A simple, diastereoselective, inexpensive, and efficient route for the synthesis of highly functionalized piperidines by the condensation of β-keto-esters, aromatic aldehydes and anilines using HH3PW12O40 as a catalyst is described. The catalyst could be easily recovered after completion of the reaction and reused without a considerable change in its activity. Furthermore, in most cases the piperidine precipitates out of solution.

Farnesyltransferase (FTase) and geranylgeranyltransferase type-I (GGTase-I) are two members of protein prenyltransferases, which play critical roles in lipid post-translational modifications. Potent inhibitors of FTase and GGTase-I have been confirmed to show favorable influence on the therapies of various diseases, such as cancers, malaria and Toxoplasmosis. However, designing highly specific inhibitors toward FTase or GGTase-I without influencing their binding affinity remains a big challenge. In this work, molecular docking, molecular dynamics (MD) simulations and MM/GBSA free energy calculations were employed to study the bindings of two highly selective inhibitors (lonafarnib and GGTI-2133) towards FTase or GGTase-I. The specificities of the studied inhibitors derived from the predicted binding free energies are consistent with the experimental data. The analysis of the energetic components illustrates that both the non-polar and polar interactions play critical roles in determining the specificity between FTase and GGTase-I. Moreover, the protein-inhibitor interaction spectra for the studied inhibitors were determined through the decomposition of the binding free energies, and the important residues for binding and specificity were highlighted. Our study provides useful information for the rational design of selective FTase or GGTase-I inhibitors.

In pursuit of utilizing combinatorial peptide libraries on beads, rapid and robust screening is one of the key steps for the success of high-throughput process. We have introduced improved structural features that greatly facilitate a MALDI-MS/MS-based sequencing, associated with easy and fast synthesis and analysis of such libraries. Whilst commonly used MS-based analysis involves in sophisticated procedures such as ladder synthesis, encoding tags are not required in our MS/MS-based sequencing platform. Fragment peaks in an acquired MS/MS should be outstanding in line with correct identification of parent mass in the preceding MS. To meet these requirements a one-bead-one-compound (OBOC) peptide library was designed by placing a positively charged arginine at C-terminus. As well as enhancing the overall ionization efficiency, arginine appended in all y-ion fragments generates a series of doublet peaks under MS/MS environments, which can speed up the sequencing process in conjunction with high accuracy. It is another strong benefit that the designed library significantly suppresses the adverse formation of sodium ion adducts, which seriously jeopardizes the sequencing, especially of peptides containing negatively charged amino acids. A peptide library constructed with D-amino acids was applied to screening against a clinically significant biomarker, C-reactive protein (CRP). Through the screening of focused libraries narrowed down from a comprehensive library, several hexamer peptide ligands were successfully identified and their binding affinity and specificity towards CRP were validated by surface plasmon resonance (SPR) and dot blot experiments.

Carbon nanotubes are the interesting class of materials with wide range of applications. They have excellent physical, chemical and electrical properties. Numerous reports were made on the antiviral activities of carbon nanotubes. However the mechanism of antiviral action is still in infancy. Herein we report, our recent novel findings on the molecular interactions of carbon nanotubes with the three key target proteins of HIV using computational chemistry approach. Armchair, chiral and zigzag CNTs were modeled and used as ligands for the interaction studies. The structure of the key proteins involved in HIV mediated infection namely HIV- Vpr, Nef and Gag proteins were collected from the PDB database. The docking studies were performed to quantify the interaction of the CNT with the three different disease targets. Results showed that the carbon nanotubes had high binding affinity to these proteins which confirms the antagonistic molecular interaction of carbon nanotubes to the disease targets. The modeled armchair carbon nanotubes had the binding affinities of -12.4 Kcal/mole, -20 Kcal/mole and -11.7 Kcal/mole with the Vpr, Nef and Gag proteins of HIV. Chiral CNTs also had the maximum affinity of -16.4 Kcal/mole to Nef. The binding affinity of chiral CNTs to Vpr and Gag was found to be -10.9 Kcal/mole and -10.3 Kcal/mole respectively. The zigzag CNTs had the binding affinity of -11.1 Kcal/mole with Vpr, -18.3 Kcal/mole with Nef and -10.9 with Gag respectively. The strong molecular interactions suggest the efficacy of CNTs for targeting the HIV mediated retroviral infections.

The attempts to increase novel drug productivity through creative discovery technologies have fallen short of producing the satisfactory results. For these reasons, evolved from the concept of drug repositioning, “privileged structure”-guided scaffold re-evolution/refining is a primary strategy to identify structurally novel chemotypes by modifying the central core structure and the side-chain of the existing active compounds, or to exploit undescribed bioactivites by making full use of readily derivatized motifs with well-established synthetic protocols. Herein, we review the basic tricks of exploiting privileged structures for scaffold re-evolution/refining. The power of this strategy is exemplified in the discovery of other new therapeutic applications by refining privileged structures in anti-viral agents.

Acetylcholinesterase (AChE) is responsible for hydrolysis of acetylcholine (ACh), a function, which if disrupted, leads to cholinergic syndrome. Carbamates (CB) and organophosphorus compounds (OP) are AChE inhibitors, toxic and capable of causing severe poisoning or death to exposed individuals. The AChE reactivation is considered the main function of the oximes. In case of poisoning by CB, there is no consistent data in the literature for an oxime reactivation mechanism. In this work, we evaluated the affinity and reactivity of oximes with activity already reported against AChE inhibited by the OP chemical warfare agent ciclosarin, with MmAChE and HsAChE active sites inhibited by the CB pesticide carbofuran. Thus, our theoretical data indicate that HLO-7, BI-6 and K005 compounds may be promising reactivators of AChE inhibited by carbofuran.