Current Topics in Medicinal Chemistry - Volume 17, Issue 25, 2017

After a short review dealing with bioorganometallic chemistry, the synthesis of tetracarbonyl(pyrrolylimine) complexes of rhenium bearing chirality on the pyrrolyl ligands was reported. The reactivity of these compounds towards the substitution of one carbonyl ligand with triphenyl phosphine, tricyclohexyl phosphine and trimethyl phosphite was studied. The rhenium becoming a stereogenic center in that transformation, the resulting tricarbonyl species were obtained as mixtures of diastereomers, with diastereomeric excesses varying from 8 to 84%, according to the reaction conditions and the relative steric hindrances of the pyrrolylimine and the organophosphorus ligands. These bioorganometallics are potential CO releasing molecules that could be used in the field of medicinal chemistry.

Metabolisms represent highly organized systems characterized by strong regulations satisfying the mass conservation principle. This makes a whole chemical resource to be competitively shared between several ways at both intra-and inter-molecular scales. Whole resource sharing can be statistically translated by a constant sum-unit constraint which represents the basis of simplex mixture rule. In this work, a new simplex-based simulation approach was developed to extract scaffold information on metabolic processes controlling molecular diversity from a wide set of observed chemical structures. Starting from a wide dataset of chemical structures initially classified into p clusters, a machine learning process was applied by linearly combining the p clusters j through several (N) samplings of a constant number (n) of molecules by respecting different clusters' weights (wj/w) given by Scheffé's mixture matrix. At the output of mixture design, the N molecular linear combinations lead to calculate N barycentric molecules integrating the characteristics of the different weighted clusters. The mixture-design was iterated by bootstrap technique for extensive exploration of chemical variability between and within clusters. Finally, the K response matrices resulting from K iterated mixture designs were averaged to calculate a smoothed matrix containing scaffold information on regulation processes responsible for molecular diversification at inter- and intra-molecular (atomic) scales. This matrix was used as a backbone for graphical analysis of multidirectional positive and negative trends between atomic characteristics (chemical substitutions) at both mentioned scales. This new simplex approach was illustrated by cycloartane- based saponins of Astragalus genus by combining three desmosylation clusters characterized by relative glycosylation levels of different aglycones' carbons.

This article reviews the innovative and original concept the “squalenoylation”, a technology allowing the formulation of a wide range of drug molecules (both hydrophilic and lipophilic) as nanoparticles. The "squalenoylation" approach is based on the covalent linkage between the squalene, a natural and biocompatible lipid belonging to the terpenoid family, and a drug, in order to increase its pharmacological efficacy. Fundamentally, the dynamically folded conformation of squalene triggers the resulting squalene-drug bioconjugates to self-assemble as nanoparticles of 100-300 nm. In general, these nanoparticles showed long blood circulation times after intravenous administration and improved pharmacological activity with reduced side effects and toxicity. This flexible and generic technique opens exciting perspectives in the drug delivery field.

Herein is described in silico repositioning, design, synthesis, biological evaluation and structure-activity relationship (SAR) of an original class of anti-inflammatory agents based on a polyaromatic pharmacophore structurally related to bisacodyl (BSL) drug used in therapeutic as laxative. We describe the potential of TOMOCOMD-CARDD methods to find out new anti-inflammatory drug-like agents from a diverse series of compounds using the total and local atom based bilinear indices as molecular descriptors. The models obtained were validated by biological studies, identifying BSL as the first anti-inflammatory lead-like using in silico repurposing from commercially available drugs. Several biological in vitro and in vivo assays were performed in order to understand its mechanism of action. A set of analogues of BSL was prepared using low-cost synthetic procedures and further biologically investigated in zebrafish models. Compound 5c and 7e exhibited the best antiinflammatory activities and represent new promising anti-inflammatory agents for further preclinical development.

Leishmaniasis is a neglected tropical disease responsible for the ninth largest disease burden in the world threatening 350 million people mostly in developing countries. The lack of efficacy, severe adverse effects, long duration, high cost and parenteral administration of the current therapies result in poor patient compliance and emergence of resistance. Leishmaniasis' unmet need for safer, affordable and more effective treatments is only partly addressed by today's global health product pipeline that focuses on products amenable to rapid clinical development, mainly by reformulating or repurposing existing drugs for new uses. Excipients are necessary for ensuring the stability and bioavailability of currently available antileishmaniasis drugs which in their majority are poorly soluble or have severe side-effects. Thus, selection of excipients that can ensure bioavailability and safety as well as elicit a synergistic effect against the Leishmania parasites without compromising safety will result in a more efficacious, safe and fast to market medicine. We have evaluated the in vitro activity of 30 commercially available generally regarded as safe (GRAS) excipients against different Leishmania spp., their cytotoxicity and potential use for inclusion in novel formulations. Amongst the tested excipients, the compounds with higher selectivity index were Eudragit E100 (cationic triblock copolymer of dimethylaminoethyl methacrylate, butyl methacrylate, and methyl methacrylate), CTAB (cetyltrimethylammonium bromide, cationic), lauric acid, Labrasol (non-ionic, caprylocaproyl polyoxyl-8 glycerides) and sodium deoxycholate. An ideal excipient needs to possess amphiphilic nature with ionic/polar groups and possess a short or medium fatty acid chain such as lauric (C12), capric (C10) or caprylicacid (C8). Inclusion of these excipients and identification of the optimal combination of drug and excipients would lead to a more effective and safer antileishmanial therapies.