Turning Waste into Useful Products by Photocatalysis with Nanocrystalline TiO Thin Films: Reductive Cleavage of Azo Bond in the Presence of Aqueous Formate.

UV-photoexcitation of TiO in contact with aqueous solutions of azo dyes does not imply only its photocatalytic degradation, but the reaction fate of the dye depends on the experimental conditions. In fact, we demonstrate that the presence of sodium formate is the switch from a degradative pathway of the dye to its transformation into useful products. Laser flash photolysis experiments show that charge separation is extremely long lived in nanostructured TiO thin films, making them suitable to drive both oxidation and reduction reactions.

Nasal administration of nanoencapsulated geraniol/ursodeoxycholic acid conjugate: Towards a new approach for the management of Parkinson's disease.

The combined use of different therapeutic agents in the treatment of neurodegenerative disorders is a promising strategy to halt the disease progression. In this context, we aimed to combine the anti-inflammatory properties of geraniol (GER) with the mitochondrial rescue effects of ursodeoxycholic acid (UDCA) in a newly-synthesized prodrug, GER-UDCA, a potential candidate against Parkinson's disease (PD). GER-UDCA was successfully synthetized and characterized in vitro for its ability to release the active compounds in physiological environments.

Bile salt-coating modulates the macrophage uptake of nanocores constituted by a zidovudine prodrug and enhances its nose-to-brain delivery.

We have previously demonstrated that the ester conjugation of zidovudine (AZT) with ursodeoxycholic acid (UDCA) allows to obtain a prodrug (U-AZT) which eludes the active efflux transporters (AET). This allows the prodrug to more efficiently permeates and remains in murine macrophages than the parent compound. Here we demonstrate that U-AZT can be formulated, by a nanoprecipitation method, as nanoparticle cores coated by bile acid salt (taurocholate or ursodeoxycholate) corona, without any other excipients.

Native Quercetin as a Chloride Receptor in an Organic Solvent.

The binding properties of quercetin toward chloride anions were investigated by means of ¹H-NMR, C-NMR, and electrospray ionization mass spectrometry (ESI-MS) measurements, as well as computational calculations. The results indicate that quercetin behaves primarily as a ditopic receptor with the binding site of the B ring that exhibits stronger chloride affinity compared to the A ring. However, these sites are stronger receptors than those of catechol and resorcinol because of their conjugation with the carbonyl group located on the C ring.

UDP-GlcNAc Analogues as Inhibitors of O-GlcNAc Transferase (OGT): Spectroscopic, Computational, and Biological Studies.

A series of glycomimetics of UDP-GlcNAc, in which the β-phosphate has been replaced by either an alkyl chain or a triazolyl ring and the sugar moiety has been replaced by a pyrrolidine ring, has been synthesized by the application of different click-chemistry procedures. Their affinities for human O-GlcNAc transferase (hOGT) have been evaluated and studied both spectroscopically and computationally. The binding epitopes of the best ligands have been determined in solution by means of saturation transfer difference (STD) NMR spectroscopy.

Enantioselective Dearomatization of Alkylpyridiniums by N-Heterocyclic Carbene-Catalyzed Nucleophilic Acylation.

A chiral NHC-catalyzed dearomatizing reaction of activated N-alkylpyridinium salts with aliphatic aldehydes is described. The resulting acylated 1,4-dihydropyridines have been obtained with complete C4 regioselectivity and enantioselectivities in the range 52-78% ee. The (4R)-absolute configuration of the synthesized compounds has been determined by the TD-DFT simulation of the electronic circular dichroism spectra.

Cross-benzoin and Stetter-type reactions mediated by KOtBu-DMF via an electron-transfer process.

The condensation of aromatic α-diketones (benzils) with aromatic aldehydes (benzoin-type reaction) and chalcones (Stetter-type reaction) in DMF in the presence of catalytic (25 mol%) KOtBu is reported. Both types of umpolung processes proceed with good efficiency and complete chemoselectivity. On the basis of spectroscopic evidence (MS analysis) of plausible intermediates and literature reports, the occurrence of different ionic pathways have been evaluated to elucidate the mechanism of a model cross-benzoin-like reaction along with a radical route initiated by an electron-transfer process to benzil from the carbamoyl anion derived from DMF.

Nucleophilic and electrophilic double aroylation of chalcones with benzils promoted by the dimsyl anion as a route to all carbon tetrasubstituted olefins.

Dimsyl anion promoted the polarity reversal of benzils in a Stetter-like reaction with chalcones to give 2-benzoyl-1,4-diones (double aroylation products), which, in turn, were converted into the corresponding tetrasubstituted olefins via aerobic oxidative dehydrogenation catalyzed by Cu(OAc)2.

Acetylcholine-like and trimethylglycine-like PTA (1,3,5-triaza-7-phosphaadamantane) derivatives for the development of innovative Ru- and Pt-based therapeutic agents.

The PTA N-alkyl derivatives (PTAC2H4OCOMe)X (1X: 1a, X = Br; 1b, X = I; 1c, X = PF6; 1d, X = BPh4), (PTACH2COOEt)X (2X: 2a, X = Br; 2b, X = Cl; 2c, X = PF6), and (PTACH2CH2COOEt)X (3X: 3a, X = Br; 3c, X = PF6), presenting all the functional groups of the natural cationic compounds acetylcholine or trimethylglycine combined with a P-donor site suitable for metal ion coordination, were prepared and characterized by NMR, ESI-MS, and elemental analysis. The X-ray crystal structures of 1d and 2c were determined. Ligands 1c, 2b, and 3c were coordinated to Pt(II) and Ru(II) to give the cationic complexes cis-[PtCl2(L)2]X2 and [RuCpCl(PPh3)(L)]X (L = 1, 2, 3, X = Cl or PF6) designed with a structure targeted for anticancer activity.

Unexpected reactivity of diaryl α-diketones with thiazolium carbenes: discovery of a novel multicomponent reaction for the facile synthesis of 1,4-thiazin-3-ones.

Diaryl α-diketones do not undergo polarity reversal in the presence of (benzo)thiazolium carbenes but are engaged in a novel multicomponent reaction with water to efficiently give medicinally relevant 1,4-thiazin-3-one heterocycles. Three different sets of conditions have been optimized to furnish the title compounds in fair to excellent yields depending on the electronic properties of α-diketone aromatic substituents and thiazolium or benzothiazolium substrate. A plausible reaction mechanism is also proposed based on the isolation and characterization of the postulated key intermediate and isotopic labeling experiments.

Zidovudine and ursodeoxycholic acid conjugation: design of a new prodrug potentially able to bypass the active efflux transport systems of the central nervous system.

We have synthesized a new prodrug obtained by the 5'-ester conjugation of zidovudine (AZT), an antiviral agent substrate of active efflux transport systems (AET), with ursodeoxycholic acid (UDCA), a bile acid able to permeate into the central nervous system (CNS). We have demonstrated, by HPLC analysis, that UDCA-AZT is quickly hydrolyzed in rat plasma and whole blood (half-life <10 s). The same compound was hydrolyzed with slower rates in human plasma (half-life =7.

Thiazolium-catalyzed intermolecular Stetter reaction of linear and cyclic alkyl α-diketones.

An efficient method for the N-heterocyclic carbene (NHC)-catalyzed conjugate addition of acetyl anions to various α,β-unsaturated acceptors (Stetter reaction) has been optimized by using 2,3-butandione (biacetyl) as an alternative surrogate of acetaldehyde. The disclosed procedure proved to be compatible with microwave dielectric heating for reaction time reduction and with the use of different linear α-diketones as acyl anion donors (e.g.

Relative acidity scale of glycine- and taurine-conjugated bile acids through ESI-MS measurements.

The most important bile acids, in the form of glycine and taurine conjugates, have been ordered in terms of relative acidity scale. The measurements have been carried out using mass spectrometric techniques. The group of taurine conjugates confirm the superior acidity over the glycine derivatives.

Relative acidity scale of bile acids through ESI-MS measurements.

The anion proton affinity of the most important human bile acids and those of the corresponding keto bile acids have been examined in order to establish a true (intrinsic) relative acidity scale. The measurements have been carried out in the gas-phase using the Cooks' kinetic method. The remarkably high acidity of cholic acid with respect to the other bile acids was confirmed.

Selective removal of monoterpenes from bergamot oil by inclusion in deoxycholic acid.

A new approach for removing monoterpenes (MTs) from bergamot oil by selective inclusion in deoxycholic acid (DCA) is proposed. The inclusion process is very efficient, the included fraction being composed mainly of limonene (71.7%) and gamma-terpinene (19.

Bile acids in asymmetric synthesis and chiral discrimination.

An overview on the use of bile acid-based compounds able to catalyze transformations, control the stereochemical course of a given reaction, recognize and bind other molecules, is presented. The recent developments in inclusion discrimination of chiral and achiral guests and enantioselective recognition achieved by bile acid are described with suitable examples.

7alpha- and 12alpha-Hydroxysteroid dehydrogenases from Acinetobacter calcoaceticus lwoffii: a new integrated chemo-enzymatic route to ursodeoxycholic acid.

We report the very efficient biotransformation of cholic acid to 7-keto- and 7,12-diketocholic acids with Acinetobacter calcoaceticus lwoffii. The enzymes responsible of the biotransformation (i.e.

Preparation and characterization of some keto-bile acid azines.

New acyclic dimers of ketocholanic acids with hydrazine were obtained. Crystal structure was determined for the 3,7-dihydroxy-12-ketocholanic acid azine. Some distinctive (1)H NMR signals are assigned for the entire set of azines.

Bile acid derivatives as enantiodifferentiating host molecules in inclusion processes.

A review on the use of bile acids as hosts for molecular recognition and enantioresolution is presented. The optical resolution of different classes of organic derivatives, i.e.

Improved enantioselectivity in the epoxidation of cinnamic acid derivatives with dioxiranes from keto bile acids.

The asymmetric epoxidation of substituted cinnamic acids has been obtained in the presence of different keto bile acid derivatives as optically active carbonyl inducers and Oxone as oxygen source. Predominant or almost exclusive formation of both enantiomeric epoxides is obtained (ee up to 95%) depending on the specific substitution at carbons C(7) and C(12) of the bile acid.