Basis of a FTIR spectroscopy methodology for automated evaluation of Akt kinase inhibitor on leukemic cell lines used as model

The PI3K/Akt-signaling pathway, associated with cancer development and disease progression, is recognized to be an anti-tumor drug target that could present important therapeutic benefit. However, no targeted Akt medicines have been commercialized yet, reflecting that drug selection procedures requires significant improvement from early research to clinical trials. Thus, new methods permitting both the evaluation of cytotoxic and proliferation inhibition effect on cancer cells but also to provide a global fingerprint of the drug action mechanism of new Akt inhibitor candidates are of major interest. Because it can detect very subtle molecular changes and could provide a global fingerprint of drug effects on cells, Fourier-transform infrared (FTIR) spectroscopy appears to be a promising method to develop new time- and cost-saving tools for chemical library screening improvements. In this study, we combine FTIR spectroscopy, advanced chemometrics analysis and cross-validation by standard biological assays to establish a basis of a mid-throughput methodology for rapid and automated assessment of cell response to Akt inhibitors and quantitative evaluation of their anti-proliferative effects. Our results shows that our methodology is able (1) to detect cell response to an Akt inhibitor exposure even for very low doses, (2) to provide biochemical information of interest about its effects on the cell metabolism, lipidome, and proteome, (3) to predict accurately resulting cell proliferation inhibition rate. Thus, further based on a large spectral data base, our methodology could contribute to facilitate preliminary screening of chemical libraries and improving the selection procedure of drug candidates in laboratory routine.     

Enzyme-free detection and quantification of double-stranded nucleic acids

We have developed a fully enzyme-free SERRS hybridization assay for specific detection of double-stranded DNA sequences. Although all DNA detection methods ranging from PCR to high-throughput sequencing rely on enzymes, this method is unique for being totally non-enzymatic. The efficiency of enzymatic processes is affected by alterations, modifications, and/or quality of DNA. For instance, a limitation of most DNA polymerases is their inability to process DNA damaged by blocking lesions. As a result, enzymatic amplification and sequencing of degraded DNA often fail. In this study we succeeded in detecting and quantifying, within a mixture, relative amounts of closely related double-stranded DNA sequences from Rupicapra rupicapra (chamois) and Capra hircus (goat). The non-enzymatic SERRS assay presented here is the corner stone of a promising approach to overcome the failure of DNA polymerase when DNA is too degraded or when the concentration of polymerase inhibitors is too high. It is the first time double-stranded DNA has been detected with a truly non-enzymatic SERRS-based method. This non-enzymatic, inexpensive, rapid assay is therefore a breakthrough in nucleic acid detection.     

Binding motifs of silver in prion octarepeat model peptides: a joint ion mobility, IR and UV spectroscopies, and theoretical approach

Transition metal-ion complexation is essential to the function and structural stability of many proteins. We studied silver complexation with the octarepeat motif ProHisGlyGlyGlyTrpGlyGln of the prion protein, which shows competitive sites for metal chelation including amide, indole and imidazole groups. This octapeptide is known as a favourable transition metal binding site in prion protein. We used ion mobility spectrometry (IMS), infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory calculations (DFT) to identify the binding motifs of a silver cation on HisGlyGlyGlyTrp peptide as well as on peptide subsequences. Ultra-violet photodissociation (UVPD) and collision induced dissociation mass spectrometry together with the time-dependent density functional method was then exploited to study the influence of binding sites on optical properties and on the ground and excited states reactivity of the peptide. We show that the metal cation is bound to the π-system of the indole group and a nitrogen atom of the imidazole group and that charge transfers from the indole group to the silver cation occur in excited electronic states.     

Interference of a new cyclometallated Pt compound with Cu binding to amyloid-β peptide

Coordination of a cyclometallated Pt(II) complex (1) to an amyloid-β peptide was probed by NMR and ESI-MS. Furthermore, EPR showed that binding of 1 to the Cu(II)-amyloid-β species resulted in a reshuffling of the Cu(II) coordination sphere, which was absent or lower for the sister non cyclometallated Pt(II) complexes.     

The synthesis and characterisation of novel ferrocenyl polyphenylenes

This work describes the synthesis and characterisation of a new series of polyphenylenes with up to four ferrocenyl moieties. The synthetic route involves the preparation of a number of novel precursors. Cyclopentadienones, generated from the two-fold Knoevenagel condensation of di-ferrocenyl propanones and diketones, are used in [2 + 4] Diels-Alder cycloadditions with appropriately substituted acetylenes. 13 is amongst the compounds isolated. It is the largest ferrocenyl-supported polyaromatic hydrocarbon (PAH) to date. Prepared via a Sonogashira cross-coupling reaction between ethynyl-Fc and iodo-HBC, it comprises a hexa-peri-hexabenzocoronene (HBC) core linked via acetylene to a ferrocenyl unit (Fc). The electrochemical and absorption properties of the ferrocenyl-polyphenylenes and the fully conjugated 13 are discussed. The NLO data for 13, determined by hyper Rayleigh scattering techniques, are compared to those of similar fulleryl-based compounds in the literature.     

New [(D-terpyridine)-Ru-(D or A-terpyridine)][4-EtPhCO2]2 complexes (D = electron donor group; A = electron acceptor group) as active second-order non linear optical chromophores

The dipolar and octupolar contributions of the second order nonlinear optical properties of [(4'-(C(6)H(4)-p-D)-2,2':6',2'-terpyridine)-Ru-(4'-(C(6)H(4)-p-A)-2,2':6',2'-terpyridine)]Y(2) heteroleptic complexes (D and A are donor and acceptor groups, respectively), and related free terpyridines and homoleptic complexes, have been obtained by means of a comprehensive combination of Electric Field Induced Second Harmonic generation, Third Harmonic Generation, and Harmonic Light Scattering measurements. These results evidence how a metal can act as a bridge between two π-delocalized terpyridine moieties bearing a D and an A group, respectively, leading to a large quadratic hyperpolarizability hugely dominated by the octupolar contribution.     

Preparation of a series of N-alkyl-3-boronopyridinium halides and study of their stability in the presence of hydrogen peroxide

A simple and efficient protocol for the preparation of a series of N-alkyl-3-boronopyridinium salts is described which requires exposure of 3-pyridineboronic acid neopentylglycol ester and corresponding alkyle halide to microwave irradiation followed by boronic ester hydrolysis. The technique employed drastically reduces the reaction time and prevents thermal degradation and the formation of side products. Water solutions of the obtained boronopyridinium salts are shown to be stable at room temperature in wide pH range as well as in the presence of hydrogen peroxide at pH 10.0 for 72 h.      

A Novel Calcium-Dependent Protein Kinase 1 Inhibitor Potently Prevents Toxoplasma gondii Transmission to Foetuses in Mouse

Treatments currently used to prevent congenital toxoplasmosis are non-specific of Toxoplasma gondii and have grievous side effects. To develop a more specific and less toxic drug, we have designed SP230, an imidazo[1,2-b]pyridazine salt targeting the Toxoplasma gondii calcium-dependent protein kinase 1 (TgCDPK1) and active against acute toxoplasmosis in mice. Efficiency of SP230 to inhibit foetal transmission of the parasite was evaluated in a mouse model of congenital toxoplasmosis. Swiss mice were infected at mid-pregnancy with tachyzoites or cysts of the ME49 strain of T. gondii by intraperitoneal and oral route, respectively, and treated with SP230 at 50 mg/kg for 5 days by the same routes. Parasite burden in organs of dams and in foetuses was measured by quantitative PCR. Intraperitoneal administration of SP230 drastically reduced the number of parasites (more than 97% of reduction) in the brain and lungs of dams, and led to a reduction of 66% of parasite burden in foetuses. Oral administration of SP230 was particularly efficient with 97% of reduction of parasite burdens in foetuses. SP230 did not impact number and weight of offspring in our conditions. This inhibitor of TgCDPK1 is a promising candidate for the development of alternative therapeutics to treat infected pregnant women.     

Optimization of thickness and uniformity of photonic structures fabricated by interference lithography

We study the influence of the absorption of materials used for holographic fabrication of photonic structures on their uniformity along the film thickness. We demonstrate theoretically and experimentally a strong dependence of structure thickness and uniformity on the exposure dose of the interference pattern. A novel technique is proposed to overcome the absorption effect and to fabricate thick two- and three-dimensional structures, which are uniform throughout the film thickness. It consists of exposing once again the sample by an additional and independent counterpropagating uniform beam, which allows to compensate the diminution of the light intensity of interference pattern. These results are very useful for the fabrication of high quality polymer-based photonic crystals.     

ChemInform Abstract: First Evidence of a Phase Transition in a High‐Pressure Metal Iodate: Structural and Thermal Studies of AgIO3 Polymorphs.

A new phase of silver iodate, β‐AgIO₃, is obtained by heating α‐AgIO₃ at 2.7 GPa at <240 °C for 30 min.