Luisa Mannina

Liquid state 1H high field NMR in food analysis

2012 Elsevier B.V. All rights reserved.

Synthesis of 3-arylisocoumarins, including thunberginols A and B, unsymmetrical 3,4-disubstituted isocoumarins, and 3-ylidenephthalides via iodolactonization of methyl 2-ynylbenzoates or the corresponding carboxylic acids

3-Aryl-4-iodoisocoumarins, which were readily and efficiently prepared by regioselective iodolactonization of methyl 2-ynylbenzoates or the corresponding carboxylic acids, were used as precursors either to 3-arylisocoumarins, including naturally-occurring thunberginols A and B, or to unsymmetrical 3,4-disubstituted isocoumarins. On the other hand, (Z)- and (E)-3-iodomethylidenephthalides, which were regioselectively prepared by iodolactonization of methyl 2-ethynylbenzoate, were employed as starting materials for the stereospecific synthesis of (Z)- and (E)-3-ylidenephthalides, respectively. Some 3-arylisocoumarins and unsymmetrical 3,4-disubstituted isocoumarins showed certain cytotoxic activity against human cancer cell lines in vitro.

Acyl positional distribution of glycerol tri-esters in vegetable oils: a 13C NMR study

Abstract It has recently been shown that high-resolution 13C nuclear magnetic resonance (NMR) spectroscopy is a technique which can provide valuable information about the acyl distribution and acyl positional distribution (1,3-acyl and 2-acyl) of glycerol tri-esters of different vegetable oils. It has also been observed that many of the carbon atoms of α- and β- acyl chains in tri-acyl-glycerol show different 13C NMR chemical shifts. However, previous assignments of 13C NMR spectra are either tentative or incomplete. Thus, through a series of INADEQUATE experiments, we made a full assignment of all 13C resonances of glycerol tri-esters. We also noticed a strong concentration dependence of the shifts of all resonances. Thus, in vegetable oils, the full assignment of 13C resonances must be made by progressive addition of known glycerol tri-esters. Following this method, we report a full assignment of the 13C spectra of seed and olive oils obtaining an accurate analysis of the acyl positional distribution (1,3-acyl and 2-acyl) of glycerol tri-esters. From the knowledge of the acyl positional distribution (1,3-acyl and 2-acyl) of glycerol tri-esters interesting biochemical information can be achieved.

Studies on the transition metal catalyzed synthesis of variously substituted (E)-3-[1-(aryl)methylidene]- and (E)-3-(1-alkylidene)-3H-furan-2-ones

5-Aryl and 5-alkyl substituted (E)-3-[1-(aryl)methylidene]- and (E)-3-(1-alkylidene)-3H-furan-2-ones, (E)-9, have been selectively synthesized by cyclization of the corresponding (E)-2-(1-alkynyl)-3-aryl/alkylpropenoic acids, (E)-11, in the presence of AgNO3 or Pd-catalysts such as trans-di(μ-acetato)bis[(di-o-tolylphosphino)benzyl]dipalladium(II) or that constituted of a mixture of Et3N and PdCl2(PhCN)2 or PdCl2(CH3CN)2. in a 3 : 1 molar ratio, respectively. A representative (E)-5-aryl-3-[1-(aryl)methylidene]-3H-furan-2-one, i.e. (E)-9i, has been also prepared by a tandem process involving a Pd(O)- and Cu(I)-catalyzed cross-coupling reaction between an 1-alkyne and a (Z)-3-aryl-2-bromopropenoic acid followed by a catalytic intramolecular oxypalladation of the resulting cross-coupled product. However, when this same approach was used to prepare an (E)-5-alkyl-3-[1-(aryl)methylidene]-3H-furan-2-one, i.e. (E)-9j, a mixture of (E)-9j and the corresponding (E)(Z)-5-(1-alkylidene)-3-(aryl)methyl-5H-furan-2-one, i.e. (E)(Z)-20, was obtained. Finally, in an attempt to prepare an (E)-4-alkyl-5-aryl-3-[1-(aryl)methylidene]-3H-furan-2-one, i.e. (E)-14a, by a tandem process involving the intramolecular oxypalladation of an (E)-enynoic acid, (E)-11, followed by a cross-coupling reaction of the resulting compound with an aryl iodide, a (Z)-5-(1-alkynyl)-4-aryl-3-arylmethyl-5H-furan-2-one, i.e. (Z)-22, has been stereoselectively obtained.

NMR and chemometrics in tracing European olive oils: the case study of Ligurian samples.

An NMR and chemometric analytical approach to classify extra virgin olive oils according to their geographical origin was developed within the European TRACE project (FP6-2003-FOOD-2-A, contract number: 0060942). Olive oils (896 samples) of three consecutive harvesting years (2005, 2006, and 2007) coming from Mediterranean areas were analyzed by (1)H NMR spectroscopy. Olive oil samples from Liguria, an Italian region, were chosen as a case study and PLS-DA and SIMCA modeling analyses were used to build up statistical models both to discriminate between Ligurian and non-Ligurian olive oils and to define the Ligurian olive oil class to confirm the declared provenience.

Conversion of the Mycotoxin Patulin to the Less Toxic Desoxypatulinic Acid by the Biocontrol Yeast Rhodosporidium kratochvilovae Strain LS11

The infection of stored apples by the fungus Penicillium expansum causes the contamination of fruits and fruit-derived products with the mycotoxin patulin, which is a major issue in food safety. Fungal attack can be prevented by beneficial microorganisms, so-called biocontrol agents. Previous time-course thin layer chromatography analyses showed that the aerobic incubation of patulin with the biocontrol yeast Rhodosporidium kratochvilovae strain LS11 leads to the disappearance of the mycotoxin spot and the parallel emergence of two new spots, one of which disappears over time. In this work, we analyzed the biodegradation of patulin effected by LS11 through HPLC. The more stable of the two compounds was purified and characterized by nuclear magnetic resonance as desoxypatulinic acid, whose formation was also quantitated in patulin degradation experiments. After R. kratochvilovae LS11 had been incubated in the presence of (13)C-labeled patulin, label was traced to desoxypatulinic acid, thus proving that this compound derives from the metabolization of patulin by the yeast. Desoxypatulinic acid was much less toxic than patulin to human lymphocytes and, in contrast to patulin, did not react in vitro with the thiol-bearing tripeptide glutathione. The lower toxicity of desoxypatulinic acid is proposed to be a consequence of the hydrolysis of the lactone ring and the loss of functional groups that react with thiol groups. The formation of desoxypatulinic acid from patulin represents a novel biodegradation pathway that is also a detoxification process.

Palladium-catalyzed synthesis of stereodefined 3-[(1,1-unsymmetrically disubstituted)methylidene]isobenzofuran-1(3H)-ones and stereodefined 5-[(1,1-unsymmetrically disubstituted)methylidene]furan-2(5H)-ones

Abstract Treatment of (hetero)aryl halides with 2-(1-alkynyl)benzoic acids or ( Z )-2-en-4-ynoic acids in the presence of K 2 CO 3 and a catalytic amount of Pd(PPh 3 ) 4 provides reaction mixtures in which stereodefined 3-[(1,1-unsymetrically disubstituted)methylidene]isobenzofuran-1(3 H )-ones and stereodefined 5-[(1,1-unsymmetrically disubstituted)methylidene]furan-2(5 H )-ones, respectively, are the major products.

NMR metabolic profiling of organic and aqueous sea bass extracts: Implications in the discrimination of wild and cultured sea bass

The nuclear magnetic resonance (NMR) technique was used as analytical tool to determine the complete metabolic profiling of sea bass extracts: water-soluble metabolites belonging to different classes such as sugars, amino acids, dipeptides and organic acids as well as metabolites soluble in organic solvent such as lipids, sterols and fatty acids were identified. The metabolite profiling together with a suitable statistical analysis were used to discriminate between wild and cultured sea bass samples. Preliminary results show that discrimination between wild and cultured sea bass was obtained not only using fatty acid composition but also cholesterol and phosphatidylethanolamine and some water-soluble metabolites such as choline, trimethylamine oxide, glutamine, fumaric and malic acids.

High resolution NMR characterization of olive oils in terms of quality, authenticity and geographical origin†

This review deals with the most relevant results obtained in the last 10 years of studies of olive oils by high field nuclear magnetic resonance. Among these, quality and authenticity of olive oils, as well as geographical and variety characterization of Mediterranean olive oils, are discussed. Copyright

1H NMR-based protocol for the detection of adulterations of refined olive oil with refined hazelnut oil.

A (1)H NMR analytical protocol for the detection of refined hazelnut oils in admixtures with refined olive oils is reported according to ISO format. The main purpose of this research activity is to suggest a novel analytical methodology easily usable by operators with a basic knowledge of NMR spectroscopy. The protocol, developed on 92 oil samples of different origins within the European MEDEO project, is based on (1)H NMR measurements combined with a suitable statistical analysis. It was developed using a 600 MHz instrument and was tested by two independent laboratories on 600 MHz spectrometers, allowing detection down to 10% adulteration of olive oils with refined hazelnut oils. Finally, the potential and limitations of the protocol applied on spectrometers operating at different magnetic fields, that is, at the proton frequencies of 500 and 400 MHz, were investigated.