Pio Iannelli

YADAMP: yet another database of antimicrobial peptides

This work presents an antimicrobial peptide database (YADAMP) based on an extensive literature search. This database is focused primarily on bacteria, with detailed information for 2133 peptides active against bacteria. YADAMP was created to facilitate access to critical information on antimicrobial peptides (AMPs). The main difference between YADAMP and other web databases of AMPs is the explicit presence of antimicrobial activity against the most common bacterial strains. YADAMP allows complex queries, easily accessible through a web interface. Peptide information can be retrieved based on peptide name, number of amino acids, net charge, hydrophobic percentage, sequence motif, structure and activity against bacteria. YADAMP is suitable for reviewing information on AMPs and for structure-function analyses of peptides. The database can be accessed via a web-based browser at http://www.yadamp.unisa.it.

Preparation and characterization of new melt compounded copolyamide nanocomposites

In this work new copolyamide-layered silicate nanocomposites were prepared by melt compounding using a commercial polyamide 6-based copolymer, with a partially aromatic structure, as thermoplastic matrix. This copolyamide, having a lower melting point and improved mechanical and barrier properties respect to the homopolymer, appears an interesting material for producing nanocomposite packaging films. Hybrids with different organoclay loadings were produced by a twin-screw extruder using different extrusion rates, in order to point out the effects of both processing conditions and hybrid composition on morphology (silicate dispersion and exfoliation, orientation, matrix crystallinity) of nanocomposites. All melt-intercalated samples were submitted to structural (TEM and XRD), thermal and dynamic mechanical measurements. The performed analyses have evidenced that all hybrids exhibit mixed intercalated/exfoliated morphology and that the extent of exfoliation increases with both clay amount and extrusion rate used. Moreover, it was pointed out that the silicate nano-scale dispersion significantly affects the crystalline morphology of copolyamide matrix, stabilizing the γ-crystal phase, and the dynamic mechanical response of the hybrids, whose storage and loss moduli values result sensibly higher than those corresponding to the neat matrix.

Preparations and release characteristics of naringin and naringenin gastro-resistant microparticles by spray-drying

To prevent the drug release and degradation in gastric medium, naringin and naringenin gastro-resistant microparticles were formulated. (CAP) as coating material and spray-drying technique were tested to obtain a controlled drug release to the intestine. The influence of parameters such as the composition of the feed solution and polymer concentration on the particle yield, behavior and morphology was investigated. The microparticles were characterized by scanning electron microscopy (SEM), fluorescence microscopy (FM), and differential scanning calorimetry (DSC). In vitro dissolution studies, carried out using a pH change method, revealed that gastro-resistant naringin- and naringenin-loaded microparticles are obtainable from 2% buffer aqueous feed solutions in different polymer/drug ratios (1:1, 3:1, 5:1) by spray-drying. The method appears to be an efficient means of stabilizing these labile drugs and of obtaining a biphasic release trend due to the adequate coating properties and to the pH dependent solubility of the polymer.

Crystal structure of a mesogenic copper(II) square-planar complex bis[N-p-(n-Hexyloxy)phenyl, p-(n-heptyloxy)salicylaldiminato] copper(II)

Abstract The crystal structure of this compound, a substance which exhibits smectic meso-morphism, is triclinic, P 1 space group, with lattice constants a = 11.280(5) A, b = 13.598(1) A, c = 25.650(2) A, α = 97.85(1) A, β = 96.76(3)° and γ = 100.37(3)°. Molecules with two different conformations are present in the unit cell, and the heptyl and hexyl side-chains are extended nearly parallel to each other. The molecules are packed together in layers with their major axes inclined at 60° to the layer plane. The observed structure explains why the liquid crystal mesophases of this and related compounds are not discotic.

Discotic mesomorphism of rufigallol hexa-n-alkoxylates

Abstract Aliphatic ethers of rufigallol have been prepared and their discotic mesomorphism studied. All the compounds give enantiotropic, columnar mesophases with a regular stacking of the discs along the columns, as revealed by the X-ray diffraction patterns of the mesophases. Calorimetric data indicate a wide range of stability of the mesophase. Solid polymorphism has been demonstrated that involves both solution crystallized and melt crystallized samples.

Switching Device Based on a Thin Film of an Azo-Containing Polymer for Application in Memory Cells

Results obtained on a conductive multilevel device realized with a 100 nm azo-polymer film are reported. The capability to switch between three different conductance states makes the device versatile both for Write Once Read Many and Write Many Read Many memory cell application. The analysis of the - curves indicates that the hysteretic conductance change with the external voltage can be explained in terms of different hopping distances existing between the nearest neighbors intervening in the two conformational states of the molecular structure.

Synthesis and liquid crystalline properties of low molecular mass compounds containing the 1,4-bis(5-phenyl-1,3,4-oxadiazolyl)benzene unit

The synthesis and characterization of low molecular mass compounds containing 1,4-bis(5-phenyl-1,3,4-oxadiazolyl)benzene is reported. All compounds are fluorescent in solution. Due to the flat shape of the conjugated unit, smectic-like packing is observed at high temperatures for some of the synthesized compounds. Moreover the insertion of a lateral flexible alkoxy unit strongly destabilizes the smectic order whilst promoting the appearance of a nematic phase in the case of the shortest methoxy unit. The mesogenic character of this unit may be of interest in the synthesis of liquid crystalline polymeric systems, taking advantage of both the fluorescent properties and the peculiar molecular structure of the liquid crystalline state.

Differential effect of 2-hydroxyoleic acid enantiomers on protein (sphingomyelin synthase) and lipid (membrane) targets.

The complex dual mechanism of action of 2-hydroxyoleic acid (2OHOA), a potent anti-tumor compound used in membrane lipid therapy (MLT), has yet to be fully elucidated. It has been demonstrated that 2OHOA increases the sphingomyelin (SM) cell content via SM synthase (SGMS) activation. Its presence in membranes provokes changes in the membrane lipid structure that induce the translocation of PKC to the membrane and the subsequent overexpression of CDK inhibitor proteins (e.g., p21(Cip1)). In addition, 2OHOA also induces the translocation of Ras to the cytoplasm, provoking the silencing of MAPK and its related pathways. These two differential modes of action are triggered by the interactions of 2OHOA with either lipids or proteins. To investigate the molecular basis of the different interactions of 2OHOA with membrane lipids and proteins, we synthesized the R and S enantiomers of this compound. A molecular dynamics study indicated that both enantiomers interact similarly with lipid bilayers, which was further confirmed by X-ray diffraction studies. By contrast, only the S enantiomer was able to activate SMS in human glioma U118 cells. Moreover, the anti-tumor efficacy of the S enantiomer was greater than that of the R enantiomer, as the former can act through both MLT mechanisms. The present study provides additional information on this novel therapeutic approach and on the magnitude of the therapeutic effects of type-1 and type-2 MLT approaches. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cells Physiology, Pathology and Therapy.

Crystallization of oriented smectic polypropylene I. Thermally induced crystallization

The crystallization induced by thermal treatments of smectic polypropylene fibres has been studied. Analysis was carried out detecting the density and X-ray diffractograms. Density and diffraction data disagree on two important aspects: the critical temperature necessary to activate the crystallization process, and the effects of annealing time on the growth process. The first point seems to suggest that the observed densification at the lower temperatures is related to phenomena differing from a crystallization process, while the observed effects of the annealing time can be explained by assuming that the anisotropy of the fibre structure induces anisotropy in the phase transition and growth process. On the other hand, density and diffraction data agree in indicating that the rate and degree of crystallization increase on increasing the crystallization temperature.

Small azobenzene derivatives active against bacteria and fungi.

ATP synthase and protein kinase (PKs) are prime targets for drug discovery in a variety of diseases. It is well known that numerous stilbenes are capable to interact and inhibit ATP synthase and PKs. This work focuses on a series of azobenzene based molecules having high structural similarity with antimicrobial stilbenes. An investigation was carried out analyzing the potential toxicity of a large set of molecules by means of computational analysis. A small selection of potential low toxic molecules have been therefore synthesized, characterized and finally microbiologically tested. The synthesized compounds show potent bactericidal activity against Gram+ and a fungus, and are capable of inhibiting biofilm formation. Finally, the compounds demonstrated a thermal stability that makes them potential candidates for incorporation in polymer matrix for application as biomedical devices and food packaging.