Lucia D’Accolti

MALDI-TOF mass spectrometry detection of extra-virgin olive oil adulteration with hazelnut oil by analysis of phospholipids using an ionic liquid as matrix and extraction solvent

The adulteration of extra virgin olive oil (EVOO) with hazelnut oil (HO) is frequent and constitutes a serious concern both for oil suppliers and consumers. The high degree of similarity between the two oils as regards triacylglycerol, total sterol and fatty acid profile, complicates the detection of low percentages of HO in EVOO. However, phospholipids (PLs) are usually present in seed oils at a concentration range of 10-20 g/kg, while the amounts of PLs in VOOs are 300-400 times lower. Thus, in this work a sample pretreatment procedure focused towards the selective PLs extraction was developed; the Bligh-Dyer extraction procedure was modified introducing the ionic liquid resulting from the combination of TBA (tributylamine) and CHCA (α-Cyano-4-hydroxycinnamic acid) as extraction solvent. The selective extraction and enrichment of phospholipids from EVOO and HO samples was then achieved. The relevant extracts were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) using the same ionic liquid TBA-CHCA as MALDI matrix, that was found to be very suitable for PLs analysis. In fact, a remarkable increase of the phospholipids signals, with a simultaneous decrease of those relevant to triacylglycerols and diacylglycerols, was observed in the relevant mass spectra. The applicability of the whole method to the individuation of the presence of HO in EVOO was demonstrated by the analysis of EVOO samples progressively adulterated with variable quantities of HO, that was still detectable at a 1% contamination level.

Selective Hydroxylation of Methane by Dioxiranes under Mild Conditions

The direct conversion of methane to methanol at low temperatures was achieved selectively using dioxiranes 1a,b either in the isolated form or generated in situ from aqueous potassium caroate and the parent ketone at a pH close to neutrality. Results suggest that the more powerful dioxirane TFDO (1b) should be the oxidant of choice.

Concerning Selectivity in the Oxidation of Peptides by Dioxiranes. Further Insight into the Effect of Carbamate Protecting Groups

With use of methyl(trifluoromethyl)dioxirane (TFDO), the oxidation of some tripeptide esters protected at the N-terminus with carbamate or amide groups could be achieved efficiently under mild conditions with no loss of configuration at the chiral centers. Expanding on preliminary investigations, it is found that, while peptides protected with amide groups (PG = Ac-, Tfa-, Piv-) undergo exclusive hydroxylation at the side chain, their analogues bearing a carbamate group (PG = Cbz-, Moc-, Boc-, TcBoc-) give competitive and/or concurrent hydroxylation at the terminal N-H moiety. Valuable nitro derivatives are also formed as a result of oxidative deprotection of the carbamate group with excess dioxirane. A rationale is proposed to explain the dependence of the selectivity upon the nature of the protecting group.

First Example of a Lipophilic Porphyrin-Cardanol Hybrid Embedded in a Cardanol-Based Micellar Nanodispersion

Cardanol is a natural and renewable organic raw material obtained as the major chemical component by vacuum distillation of cashew nut shell liquid. In this work a new sustainable procedure for producing cardanol-based micellar nanodispersions having an embedded lipophilic porphyrin itself peripherally functionalized with cardanol substituents (porphyrin-cardanol hybrid) has been described for the first time. In particular, cardanol acts as the solvent of the cardanol hybrid porphyrin and cholesterol as well as being the main component of the nanodispersions. In this way a “green” micellar nanodispersion, in which a high percentage of the micellar system is derived from renewable “functional” molecules, has been produced.

Selective Synthesis of Hydroxy Analogues of Valinomycin using Dioxiranes

A synthesis of representative monohydroxy derivatives of valinomycin (VLM) was achieved under mild conditions by direct hydroxylation at the side chains of the macrocyclic substrate using dioxiranes. Results demonstrate that the powerful methyl(trifluoromethyl)dioxirane 1b should be the reagent of choice to carry out these key transformations. Thus, a mixture of compounds derived from the direct dioxirane attack at the β-(CH(3))(2)C-H alkyl chain of one Hyi residue (compound 3a) or of one Val moiety (compounds 3b and 3c) could be obtained. Following convenient mixture separation, each of the new oxyfunctionalized macrocycles became completely characterized.

Oxyfunctionalization of Non-Natural Targets by Dioxiranes. 6. On the Selective Hydroxylation of Cubane

By using methyl(trifluoromethyl)dioxirane (TFDO), the direct mono- and bishydroxylation of cubane could be achieved in high yield under remarkably mild conditions. Comparison of the rates of dioxirane O-insertion with those of standard reference compounds, such as adamantane and cyclopropane, as well as ab initio computations provide useful hints concerning the mechanism of these transformations.

Antitumor potential of conjugable valinomycins bearing hydroxyl sites: In vitro studies

Following our pioneering studies on the direct and efficient introduction of derivatizable hydroxyl handles into the valinomycin (VLM, 1) structure, a K(+)-ionophore with potent antitumor activity, the ensuing conjugable analogues (HyVLMs 2, 3, and 4) have herein been compared to the parent macrocycle for their potential antiproliferative effects on a panel of cancer cell lines, namely, human MCF-7, A2780, and HepG2, as well as rat C6 cells. On the basis of IC50 values, we find that hydroxyl analogues 3 and 4 are only moderately less active than 1, while analogue 2 experiences a heavily diminished activity. Cytofluorimetric analyses of MCF-7 cells treated with HyVLMs suggest that the latter depolarize mitochondria, thus retaining the typical VLM behavior. It is likely that C6 cells, for which the exceptionally potent cytotoxicity of VLM has never reported previously, follow the same fate, as evidenced by alteration of mitochondrial morphology upon incubation with each ionophore.

Catalytic Activity of Silicon Nanowires Decorated with Gold and Copper Nanoparticles Deposited by Pulsed Laser Ablation

Silicon nanowires (SiNWs) decorated by pulsed laser ablation with gold or copper nanoparticles (labeled as AuNPs@SiNWs and CuNPs@SiNWs) were investigated for their catalytic properties. Results demonstrated high catalytic performances in the Caryl–N couplings and subsequent carbonylations for gold and copper catalysts, respectively, that have no precedents in the literature. The excellent activity, attested by the very high turn over number (TON) values, was due both to the uniform coverage along the NW length and to the absence of the chemical shell surrounding the metal nanoparticles (MeNPs). A high recyclability was also observed and can be ascribed to the strong covalent interaction at the Me–Si interface by virtue of metal “silicides” formation.

One-Pot Conversion of Epoxidized Soybean Oil (ESO) into Soy-Based Polyurethanes by MoCl2O2 Catalysis

An innovative and eco-friendly one-pot synthesis of bio-based polyurethanes is proposed via the epoxy-ring opening of epoxidized soybean oil (ESO) with methanol, followed by the reaction of methoxy bio-polyols intermediates with 2,6-tolyl-diisocyanate (TDI). Both synthetic steps, methanolysis and polyurethane linkage formation, are promoted by a unique catalyst, molybdenum(VI) dichloride dioxide (MoCl2O2), which makes this procedure an efficient, cost-effective, and environmentally safer method amenable to industrial scale-up.

TiO2@PEI-Grafted-MWCNTs Hybrids Nanocomposites Catalysts for CO2 Photoreduction

Anatase (TiO2) and multiwalled carbon nanotubes bearing polyethylenimine (PEI) anchored on their surface were hybridized in different proportions according to a sol-gel method. The resulting nanocomposites (TiO2@PEI-MWCNTs), characterized by BET, XRD, XPS, SEM, and UV techniques, were found efficient catalysts for CO2 photoreduction into formic and acetic acids in water suspension and under visible light irradiation. PEI-grafted nanotubes co-catalysts are believed to act as CO2 activators by forming a carbamate intermediate allowing to accomplish the first example in the literature of polyamines/nanotubes/TiO2 mediated CO2 photoreduction to carboxylic acids.