Maria Luisa Di Gioia

The food contaminants bisphenol A and 4-nonylphenol act as agonists for estrogen receptor α in MCF7 breast cancer cells

Xenoestrogens are chemically distinct industrial products potentially able to disrupt the endocrine system by mimicking the action of endogenous steroid hormones. Among such compounds, the ubiquitous environmental contaminants bisphenol A (BPA) and 4-nonylphenol (NPH) may promote adverse effects in humans triggering estrogenic signals in target tissues. Following a research program on human exposure to endocrine disruptors, we found contamination of fresh food by BPA and NPH. More important, these contaminants were found to display estrogen-like activity using as a model system the estrogen-dependent MCF7 breast cancer cells (MCF7wt); its variant named MCF7SH, which is hormone-independent but still ERα-positive, and the steroid receptor-negative human cervical carcinoma HeLa cells. In transfection experiments BPA and NPH activated in a direct manner the endogenous ERα in MCF7 wt and MCF7SH cells, as the antiestrogen hydroxytamoxifen was able to reverse both responses. Moreover, only the hormone-binding domains of ERα and ERβ expressed by chimeric proteins in HeLa cells were sufficient to elicit the transcriptional activity upon BPA and NPH treatments. Transfecting the same cell line with ERα mutants, both contaminants triggered an estrogen-like response. These transactivation properties were interestingly supported in MCF7wt cells by the autoregulation of ERα which was assessed by RT-PCR for the mRNA evaluation and by immunoblotting and immunocytochemistry for the determination of protein levels. The ability of BPA and NPH to modulate gene expression was further confirmed by the upregulation of an estrogen target gene like pS2. As a biological counterpart, concentrations of xenoestrogens eliciting transcriptional activity were able to stimulate the proliferation of MCF7wt and MCFSH cells. Only NPH at a dose likely too high to be of any physiological relevance induced a severe cytotoxicity in an ERα-independent manner as ascertained in HeLa cells. The estrogenic effects of such industrial agents together with an increasing widespread human exposure should be taken into account for the potential influence also on hormone-dependent breast cancer disease.

Quantitative determination of fatty acid chain composition in pork meat products by high resolution 1H NMR spectroscopy

High resolution (1)H NMR spectroscopy was proposed for the determination of the fatty acid chain profile of lipids in pork meat products during ripening. Two typical Mediterranean PDO salami produced in Calabria, a region in the Southern Italy, were chosen as a case of study. Quantitative NMR analysis provided the fatty acid chain profiles of total lipid extracts. The transesterification of total lipid extracts furnished FAME mixtures that enabled quantitation of fatty acid acyl chains in the acylglycerol and FFA portions. In all cases, oleyl chains were predominant, and high amounts of polyunsaturated fatty acid chains were observed. The proposed spectroscopic method allowed also the estimation of the most important nutritional parameters of dry fermented meat products.

Synthesis of D-erythro-sphinganine through serine-derived α-amino epoxides.

A total synthesis of D-erythro-sphinganine [(2S,3R)-2-aminooctadecane-1,3-diol] starting from commercial N-tert-butyloxycarbonyl-L-serine methyl ester is described. The approach is based on the completely stereoselective preparation of an α-amino epoxide obtained by treating a protected L-serinal derivative with dimethylsulfoxonium methylide. The oxirane synthon is obtained with an anti configuration fitting the (2S,3R) stereochemistry of the 2-amino-1,3-diol polar head of D-erythro-sphinganine. The synthetic procedure afforded the target compound in a 68% overall yield based on the initial amount of the starting L-serine material.

A preparation of N-Fmoc-N-methyl-α-amino acids and N-nosyl-N-methyl-α-amino acids

A convenient route for the synthesis of lipophilic N-Fmoc-N-methyl-α-amino acids and N-nosyl-N-methyl-α-amino acids, interesting building blocks to be used for the preparation of N-methylated peptides, is presented. Both nosyl- and Fmoc-protected monomers are accessible, so these compounds can be used in solution as well as in solid phase peptide synthesis. The methodology is based on the use of benzhydryl group to protect temporarily the carboxyl function of N-nosyl-α-amino acids and on the subsequent methylation of the N-nosyl-α-amino acid benzhydryl esters with diazomethane. The benzhydryl esters offer several beneficial features such as simple preparation, stability to methylation and selective deprotection under mild conditions. The overall procedure is highly efficient in that the adopted conditions keep the chiral integrity of amino acid precursors and the process does not require chromatographic purification of the methylated products.

Intramolecular displacement of phenylselenone by a hydroxy group: stereoselective synthesis of 2-substituted tetrahydrofurans.

An efficient and stereocontrolled synthesis of 2-substituted tetrahydrofurans has been achieved. The approach employs the asymmetric reduction of γ-phenylseleno ketones obtained by three different procedures that are peculiarly applied to the synthesis of such compounds. Finally, the intramolecular substitution of the phenylselenone residue by the oxygen atom of a hydroxy group gives the tetrahydrofuran ring.

A new non-natural arginine-like amino acid derivative with a sulfamoyl group in the side-chain

Sulfamoylation of the l-ornithine methyl ester side-chain generates a non-natural arginine isostere which can be coupled with N-Fmoc-l-proline to synthesize analogues which maintain the structural characteristics of the biologically important Pro-Arg dipeptide sequence. As a probe of its biological importance, the sulfamoylated amino acid derivative was also incorporated as P1 residue in tripeptide structures matching the C-terminal subsequence of fibrinogen. The reported results demonstrate that the functionalization of l-ornithine side-chain with a neutral sulfamoyl group can generate an arginine bioisostere which can be used for the synthesis of prototypes of a new class of human thrombin inhibitors.

N-Methylated α-Amino Acids And Peptides: Synthesis And Biological Activity

The simplest and minimal modification of a single amino acid or peptide bonds is represented by N-methylation. This can improve the pharmacokinetic properties of biologically active peptides as well as resulting in analogues that show specific biological activity such as enzyme inhibitors, receptor antagonists and agonists, building blocks in combinatorial chemistry for the screening of new potential drugs. Further, structural and conformational studies performed with N-methylated analogues of natural amino acids and peptides enabled to (i) produce stable foldamers with different topology with respect to the helix of natural and endogenous peptides, (ii) confer to modified peptides high stability against proteases and (iii) enhance lipophilicity and bioavailability for pharmacological purposes. Consequentially, it is crucial to provide optically pure N-methyl-amino acids and N-methylated peptides with a large supply. The present report will focus on the results obtained in the last decade in the field of chemical synthetic methodologies for the N-methylation of amino acids.

Synthesis of enantiopure sugar-decorated six-armed triptycene derivatives

Summary A new class of molecules with a triptycene rigid core surrounded by six monosaccharide residues was synthesized. Hexakis(bromomethyl) substituted triptycene was converted into a six-armed triptycene azide (2,3,6,7,14,15-hexakis(azidomethyl)-9,10-dihydro-9,10-[1’,2’]benzenoanthracene). The key step of the synthesis was the cycloaddition of the azide to 2-propyn-1-yl β-D-gluco- or galactopyranosides. All products were isolated in good yields and were fully characterized.

A straightforward chemical synthesis of 17-ketosteroids by cleavage of the C-17-dihydroxy acetone side chain in corticosteroids.

A facile and convenient approach to 17-ketosteroids is described. Treatment of steroids containing the C-17-dihydroxy acetone side chain with an excess of sodium methoxide in dry 1,4-dioxane under reflux, affords high yields of the corresponding 17-ketosteroids that are recovered as pure products, without the need of further purification.

A facile approach to steroidal 20-hydroxy-17(20)-en-21-aldehydes: important intermediates in the biological 17-dehydroxylation of C-17 dihydroxyacetone steroids

A novel and straightforward route to steroidal Z- and E-enol aldehydes is presented. Acid-catalysed treatment allows formal dismutation of corticosteroids, affording good yields of the related enol compounds which can be easily separated and purified.