Roberto Ferroni

Facile synthesis of 2-nitroalkanols by tetramethylguanidine (TMG)-catalyzed addition of primary nitroalkanes to aldehydes and alicyclic ketones

Abstract Tetramethylguanidine-catalyzed addition of primary nitroalkanes to aldehydes and alicyclic ketones constitutes a practical means to perform the nitro-aldol reaction (Henry reaction). The very mild conditions employed, together with the short reaction times, make the procedure tolerant of a range of functionalities and highly versatile for the synthesis of a variety of 2-nitroalkanols.

Inhibition of 'in vitro' tumor cell growth by aromatic polyamidines exhibiting antiproteinase activity.

Aromatic polyamidines containing two, three or four benzamidine residues inhibit proteinase activity and proliferation of different human tumor cell lines, including leukemic (K562, HEL), melanoma (Colo 38) and B-lymphoid (WI-L2) cell lines. In addition, the benzamidine derivatives analysed in the present study inhibit cell growth of the Chinese hamster FHO6T1-1 cell line, obtained after transfection of primary lung cells with the activated human T24-Ha-ras-1 oncogene.After treatment of FHO6T1-1 cells with benzamidine derivatives, a sharp decrease of the content of Ha-ras-1 mRNA was found, but not of transferrin receptor mRNA.We found that inhibition of cell proliferation by tetra-benzamidine derivatives is not restricted to tumor cells, but concerns also non-tumorigenic cell lines as well as normal primary fibroblasts. Therefore, our analysis was extended to di- and tri-benzamidine derivatives, which could be proposed as useful substrates in the synthesis of drug-conjugated monoclonal antibodies or growth factors. The data obtained demonstrate that these latter compounds and their halo-derivatives also exhibit strong antiproliferative effects onin vitro cultured cells.

Tetra-p-amidinophenoxy-propane as a probe of the specificity site of serine proteases

Enea MENEGATTI, Mario GUARNERI, Roberto FERRONI, Martin0 BOLOGNESI+, Paolo ASCENZI* and Eraldo ANTONINI*> Institute of Pharmaceutical Chemistry, Univ. of Ferrara, Via Scandiana 21,441OO Ferrara, +Institute of Crystallography, Univ. of Pavia, Vip Bassi 4,271OO Pavia, *CNR Center for Molecular Biology, Institutes of Chemistry and Biochemistry, Faculty of Medicine, Univ. of Rome, piazzale Aldo More 3, 00185 Rome, Italy

Differential effects of benzamidine derivatives on the expression of c-myc and HLA-DRα genes in a human B-lymphoid tumor cell line

In this paper, we report the effects of aromatic tetra amidines (TAPP-H) on cell growth and gene expression of a B-lymphoid human tumor cell line, WI-L2. The results obtained give evidence (a) for inhibition of cell proliferation by TAPP-H; (b) for stronger antiproliferative activity of TAPP-halo derivatives; (c) for TAPP-mediated inhibition of accumulation of c-myc RNA sequences but not of HLA-DR alpha mRNA and DR antigens. These results suggest that this class of antiproliferative compounds exhibit differential effects on cell-cycle specific and differentiation specific genes. In addition, also TAPP-related compounds containing 2 (DAPP) or 3 (TAPB) benzamidine residues retain inhibitory activity on the proliferation of WI-L2 cells. These latter compounds might be proposed as useful substrate in the synthesis of drug-conjugated monoclonal antibodies or growth factors.

AROMATIC TETRA-AMIDINES: SYNTHESIS OF HALO-DERIVATIVES AND THEIR ANTIPROTEOLYTIC ACTIVITY

Mono-halo derivatives of 1,3-di-(p-amidinophenoxy)-2,2-bis-(p-amidinophenoxymethyl)p ropane (TAPP-H) have been synthesized and their inhibitory effect on the bovine trypsin, bovine thrombin and porcine pancreatic kallikrein catalyzed hydrolysis of p-nitroanilides of amino acids was investigated, at pH 8.1 and 37 degrees, in parallel with that of TAPP-H and benzamidine. The addition of a halogen (Cl, Br or I) at position 2 of each benzamidine moiety of TAPP-H is accompanied by an increase of the inhibitory effect. This is especially evident in the case of porcine pancreatic kallikrein inhibition by TAPP-Cl. The structural basis of the different inhibitory effect of TAPP-H, TAPP-halo derivatives and benzamidine on the catalyzed hydrolysis of the proteinases examined are discussed and the role of Asp-189 in bovine trypsin, Asp-189 and Glu-149 or Asp-192 in bovine thrombin and Asp-189 and Asp-A148 or Glu-150 in porcine pancreatic kallikrein is focused.

Inhibition of Serine Proteinases by Tetra-p-Amidinophenoxy-neo-Pentane: Thermodynamic and Molecular Modeling Study

The inhibitory effect of the aromatic tetra-benzamidine derivative tetra-p-amidinophenoxy-neo-pentane (TAPP) on the catalytic properties of beta-trypsin (EC 3.4.21.4), alpha-thrombin (EC 3.4.21.5), factor Xa (EC 3.4.21.6), Lys77-plasmin (EC 3.4.21.7) and beta-kallikrein-B (EC 3.4.21.35) was investigated (between pH 2 and 8, I = 0.1 M; T = 37 +/- 0.5 degrees C), and analyzed in parallel with that of benzamidine, commonly taken as a molecular inhibitor model of serine proteinases. Over the whole pH range explored, TAPP and benzamidine show the same values of the dissociation inhibition constant (Ki) for beta-trypsin; at variance with the affinity of TAPP for alpha-thrombin, factor Xa, Lys77-plasmin and beta-kallikrein-B which is higher than that found for benzamidine association around neutrality, but tends to converge in the acidic pH limb. On lowering the pH from 5.5 to 3.0, values of Ki for TAPP binding to beta-trypsin as well as for benzamidine association to all the enzymes investigated decreased thus reflecting the pK-shift, upon inhibitor binding, of a single ionizing group. Over the same pH range, values of Ki for TAPP binding to alpha-thrombin, factor Xa, Lys77-plasmin and beta-kallikrein-B may be described as depending on the pK-shift, upon inhibitor association, of two equivalent proton-binding amino acid residues. Considering the X-ray three-dimensional structures and the computer-generated molecular models of serine proteinases: TAPP and :benzamidine adducts, the observed binding behaviour of TAPP and benzamidine to the enzymes considered has been related to the inferred stereochemistry of proteinase: inhibitor contact region(s).

Pig liver esterase (PLE)-mediated resolution of N-substituted 4-benzoyloxy-3-carbomethoxypiperidines: a convenient preparation of 4-hydroxy- and 4-benzoyloxy-3-carbomethoxypiperidines in enantiomerically pure form

Abstract Pig liver esterase (PLE) afforded smooth chemical resolution of racemic N -substituted 4-(benzoyloxy)-3-carbomethoxypiperidines. The enzyme showed good chemo- and enantioselective properties, thus allowing discrimination between the carbomethoxy and benzoate ester groups, the latter being more easily hydrolyzed. The proposed methodology also represents a practical means for the procurement of N -substituted 4-hydroxy-3-carbomethoxypiperidines in enantiomerically pure form.

Synthesys of Isoxazole and Isoxazoline Derivatives of Retinoids: Effects on Growth and Differentiation of Tumor Cells

We have studied the effects of several newly synthesized isoxazole and isoxazoline analogues of retinoids on induction of terminal differentiation and “in vitro” growth of tumor cell lines. Some of the tested compounds (VI, IXa, XIIb) exhibit: (a) ability to induce adipogenic conversion of Ha-ras-1 transformed FH06T1-1 chinese hamster fibroblasts: (b) antiproliferative activity toward tumor cell lines, including the erythroleukemic K562 and FL cell lines and the FH06T1-1 cell line. The reported data could be of interest to identify drugs of possible application in experimental anti-cancer therapy.

Aromatic tetra-amidines with antiproteolytic activity inhibit platelet aggregation and secretion

We have investigated the possibility that TAPP-H may control platelet aggregation and serotonin release induced by a series of physiological and non-physiological stimuli, that are selected on the ground of their molecular mechanism. The search of new antiplatelet molecules may have relevant implications in the therapy of haemostasis disorders

Conformational transition of the synthetic 2-15 N-terminal fragment of hen egg-white lysozyme.

It has been proposed [ 1 ] that the folding of a protein molecule begins at the amino end even before the synthesis is complete. Such a sequential mechanism presumes that the protei’n conformation is primarily due to interactions between amino acid residues close in the sequence and implies that parts of the polypeptide chain, particularly those near the terminal amino end, may fold into stable conformations that can still be recognized in the complete molecule and act as ‘internal templates’ around which the rest of the chain is folded. The results obtained by studying the conformational properties of the N-terminal eicosapeptide (S-peptide) [2, 31 of bovine pancreatic ribonuclease and of several S-peptide synthetic analogs [4] in aqueous solution and in the presence of helicogenic solvent, do not agree with the hypothetical sequential mechanism mentioned above. The hen egg-white lysozyme was shown by X-ray analysis [5] to contain three runs of helix (residues 515,24-34 and 88-96) for which the axial translation per residue and the number of residues per turn fall close to the a-helix values. The aim of the present paper is to report some preliminary conformational studies on the synthetic tetradecapeptide corresponding to the 2-l 5 N-terminal fragment of hen egg-white lysozyme. The peptide conformation has been investigated by circular dichroism in aqueous solution and in the presence of trifluoroethanol which is known to cause a transition from the random to the helical form in polypeptide systems.