On the importance of decarbonylation as a side-reaction in the ruthenium-catalysed dehydrogenation of alcohols: a combined experimental and density functional study.

We report a density functional study (B97-D2 level) of the mechanism(s) operating in the alcohol decarbonylation that occurs as an important side-reaction during dehydrogenation catalysed by [RuH2(H2)(PPh3)3]. By using MeOH as the substrate, three distinct pathways have been fully characterised involving either neutral tris- or bis-phosphines or anionic bis-phosphine complexes after deprotonation. α-Agostic formaldehyde and formyl complexes are key intermediates, and the computed rate-limiting barriers are similar between the various decarbonylation and dehydrogenation paths.

Oxinobactin and sulfoxinobactin, abiotic siderophore analogues to enterobactin involving 8-hydroxyquinoline subunits: thermodynamic and structural studies.

The synthesis of two new iron chelators built on the tris-l-serine trilactone scaffold of enterobactin and bearing a 8-hydroxyquinoline (oxinobactin) or 8-hydroxyquinoline-5-sulfonate (sulfoxinobactin) unit has been described. The X-ray structure of the ferric oxinobactin has been determined, exhibiting a slightly distorted octahedral environment for Fe(III) and a Δ configuration. The Fe(III) chelating properties have been examined by potentiometric and spectrophotometric titrations in methanol-water 80/20% w/w solvent for oxinobactin and in water for sulfoxinobactin.

Label-free femtomolar detection of target DNA by impedimetric DNA sensor based on poly(pyrrole-nitrilotriacetic acid) film.

An ultrahigh performance impedimetric DNA sensor is presented showing detection limits in the femtomolar range. This electrochemical setup was constructed initially by electrogeneration of poly(11-pyrrol-1-yl-undecanoic acid N(alpha'),N(alpha)-bis(carboxymethyl)-L-lysine amide) (poly(pyrrole-NTA)) film. The latter was then modified by the coordination of Cu(2+) ions onto the chelating NTA centers followed by the immobilization of the ssHIV-DNA previously modified by a polyhistidine tag by affinity binding.

Tracing the Entropy along a Reactive Pathway: The Energy As a Generalized Reaction Coordinate.

By using metadynamics at a temperature T0 we reconstruct the free energy FT0(E,s) as a function of the potential energy E and of a geometrical variable s. We show here that from FT0(E,s) one can estimate the free energy also at a different temperature. This allows tracing the entropy and characterizing the properties of molecular systems at all temperatures by a single simulation.

Breast cancer resistance protein (BCRP/ABCG2): new inhibitors and QSAR studies by a 3D linear solvation energy approach.

A series of compounds derived from naturally occurring flavonoids and synthetic analogs have been evaluated on cell lines overexpressing the wild-type breast cancer resistance protein (BCRP/ABCG2) half-transporter. Human ABCG2-transfected cells were used for screening their inhibitory activity. Five new natural compounds obtained from Morus mesozygia Stapf and one synthetic chromone, comprising a flavonoidic scaffold, were also evaluated.

Chalcones derivatives acting as cell cycle blockers: potential anti cancer drugs?

Chalcones (1,3-diphenylpropen-1-ones) are naturally occurring compounds belonging to the flavonoid family and are largely investigated in various therapeutic area and especially as antitumor drugs. In the latter field, the literature survey indicates that effect on the cell cycle is one of the most important targets domains of chalcones. In this review, we will shed light on: a) the structural criteria responsible for the cell cycle perturbations, b) the activity of chalcones on cell cycle molecular players or regulators c) the correlation between the chalcone-structure and proteins involved directly or not in cell cycle regulation and apoptosis by enhancement of proapoptotic molecules expression.

QSAR analysis and molecular modeling of ABCG2-specific inhibitors.

In addition to its critical role is controlling drug availability and protecting sensitive organs and stem cells through cellular detoxification, breast cancer resistance protein (BCRP/ABCG2) plays an important role in cancer cell resistance to chemotherapy, together with P-glycoprotein/ABCB1. A main approach to abolish multidrug resistance is to find out specific inhibitors of the drug-efflux activity, able to chemosensitize cancer cell proliferation. Many efforts have been primarily focused on ABCB1, discovered thirty years ago, whereas very few studies have concerned ABCG2, identified much more recently.

Antimitotic and antiproliferative activities of chalcones: forward structure-activity relationship.

A series of 59 chalcones was prepared and evaluated for the antimitotic effect against K562 leukemia cells. The most active chalcones were evaluated for their antiproliferative activity against a panel of 11 human and murine cell cancer lines. We found that three chalcones were of great interest as potential antimitotic drugs.

Direct preparation of nucleoside vinyl disulfides from 2-(trimethylsilyl)ethyl sulfides, an access to vinylthiols.

We report here a straightforward preparation of various nucleoside vinyl disulfides in high yields under mild conditions using the new reaction of vinyl 2-(trimethylsilyl)ethyl (TMSE) sulfides with sulfenyl chlorides. This reaction allows the preparation of various mixed disulfides from stable silyl sulfides without formation of oxidizable and/or unstable thiols. The easy preparation of vinyl disulfides through this reaction should offer new perspectives in vinylthiol chemistry.

Neamine dimers targeting the HIV-1 TAR RNA.

Natural aminoglycoside antibiotics, such as neomycin, target bacterial ribosomal RNA. Neomycin also binds strongly to HIV TAR and RRE RNA through the predominant interactions of its neamine core. In the search for antiviral agents targeting multiple binding sites for aminoglycosides in RNA, we report here the synthesis of new neamine dimers and a trimer in which the neamine cores are connected by different linking chains attached at the 4'- and/or 5-positions.