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Biomedical subjects

M Prato

Publications and source records attributed to M Prato.

At least 19 recordsLinked to original sources
PubMed2006

Element-specific probe of the magnetic and electronic properties of Dy incar-fullerenes.

The magnetic and electronic properties of a single atom and a pair of Dy atoms encapsulated inside fullerene carbon cages have been examined using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) as well as resonant photoelectron spectroscopy (RESPES) across the Dy M(4,5)-edge. The comparison of the measured XAS spectra with multiplet calculations indicates that the encaged Dy has a 4f( 9) configuration. The presence of Dy 5d spectral weight in the valence band is not detected by RESPES, indicating that Dy is in a formally trivalent state. The evolution of the encaged Dy orbital and spin moments of the 4f orbitals as a function of the applied magnetic field and temperature has been obtained from XMCD measurements. At 6.9 T and 4 K, both the orbital and the spin magnetic moments of the encaged Dy 4f electrons are dramatically smaller than those expected for the free Dy(3+) at saturation.

Algorithms↗
PubMed2006

Anti-inflammatory and anti-oxidant activity of a new class of phenyl-pyrazolone derivatives.

The anti-inflammatory activity of a new class of phenyl-pyrazolone derivatives, structurally related to phenidone, has been evaluated using the Croton oil ear test in mice as model of acute inflammation. Derivative 5h reduces the percentage of oedema similarly to indomethacin and more efficiently than phenylbutazone. The anti-inflammatory activity of these two reference drugs depends on their COX inhibition, but for the synthesized derivatives it has not been demonstrated a significant COX or LOX inhibition, as previously reported. While the anti-inflammatory activity of phenidone is correlated to its anti-oxidant properties, the redox potential of these compounds appears not decisive in the inflammatory process inhibition. In order to investigate the mechanism of action for these compounds, we quantified their anti-oxidant activity and the lipophilicity, and a relationship between the calculated logP and the percentage of oedema reduction was found. We hypothesize that the anti-inflammatory activity, recorded in vivo, could be related to lipophilic parameter of these compounds.

Animals↗
PubMed2004

Self-assembled monolayers of organosulphur molecules bearing calix[4]arene moieties.

We investigate the self-assembly of modified calix[4]arene on gold surfaces. Calix[4]arene was modified through a reaction sequence which led to assembling of the crown-5 moiety and to the insertion of two thioether groups into the starting molecule. The so-obtained calix[4]arene-crown-5 bis(7-thiatridecyloxy) (hereafter called calix[4]arene) was in the stable 1,3-alternate conformation. The calix[4]arene/gold interface was investigated by means of spectroscopic ellipsometry (SE), scanning tunneling microscopy (STM) and cyclic voltammetry (CV). SE data indicate a layer thickness compatible with the formation of a monomolecular layer. This result is confirmed by STM imaging which shows the formation of a high density of small pits, one gold layer deep, a typical feature of self-assembled organosulphur monolayers on gold. CV measurements performed in presence of the [Ru(NH(3))(6)(2+/3+)] redox couple indicate a passivation of the metal electrode, resulting in a reduction of the redox current, after the layer deposition. CV has also been used to investigate the selectivity properties of calix[4]arene-covered gold electrodes by measuring the redox current decrease in the presence of different salt solutions. It is found that calix[4]arene-covered electrodes are able to complex K(+) and Ba(2+), while no complexation is observed in the case of Li(+), Na(+), Cs(+), Mg(2+) and Ca(2+).

Adsorption↗
PubMed2001

Novel versatile fullerene synthons.

We report the synthesis of three novel, versatile fullerene intermediates whose main feature is the presence of an amino end group. Simple condensation reactions of these intermediates under standard conditions produce new derivatives that are useful for applications in materials science and medicinal chemistry.

Amines↗
PubMed2001

A mixed fullerene-ferrocene thermotropic liquid crystal: synthesis, liquid-crystalline properties, supramolecular organization and photoinduced electron transfer.

Grafting of a ferrocene-containing liquid-crystalline malonate derivative to C60 led to the mixed fullerene-ferrocene material 1 which gave rise to a smectic A phase. Cholesterol was used as liquid-crystalline promoter. X-ray diffraction experiments and volumetric measurements indicated that 1 is organized in double layered structures. The corresponding supramolecular organization within the mesomorphic lamellar phase is characterized by a microsegregation of the different units (ferrocene, fullerene, and cholesterol) in distinct sublayers. In such a smectic A phase, C60 imposes the arrangement of the other molecular moieties. Photophysical studies revealed that electron transfer occurs from the donor ferrocene to the electron accepting fullerene. The formation of a long-lived radical pair, with lifetimes of the order of several hundred nanoseconds, was confirmed by time-resolved spectrometry, especially in the near infrared region, in which the radical anion of the fullerene moiety displays its characteristic fingerprint absorption.

Journal Article↗
PubMed2001

A novel [60]fullerene amino acid for use in solid-phase peptide synthesis.

[see structure]. A fullerene derivative containing a free amino group has been condensed with N-Fmoc-L-glutamic acid alpha-tert-butyl ester to give a C60-functionalized amino acid. The carboxylic end of this amino acid has been deprotected in acidic conditions, and the resulting acid has been used for solid-phase peptide synthesis. The final peptide, cleaved from the resin, was very soluble in water solutions and showed antimicrobial activity against two representative bacteria.

Amino Acids↗
PubMed2001

Isolation and characterization of all eight bisadducts of fulleropyrrolidine derivatives.

We report the isolation and characterization of bisadducts of fulleropyrrolidine derivatives. The compounds were characterized by means of a variety of spectroscopic techniques, including ES-MS, UV-vis, (1)H NMR, and (13)C NMR. The whole series of bisadducts was separated for the first time in the case of the bispyrrolidines, and the determination of their structure was obtained by NMR spectroscopy with the help of HMQC and HMBC techniques.

Journal Article↗
PubMed2001

Efficient charge separation in porphyrin-fullerene-ligand complexes.

Photoprocesses associated with the complexation of a pyridine-functionalized C60 fullerene derivative to ruthenium- and zinc-tetraphenylporphyrins (tpp) have been studied by time-resolved optical and transient EPR spectroscopies. It has been found that upon irradiation in toluene, a highly efficient triplet-triplet energy transfer governs the deactivation of the photoexcited [Ru(tpp)], while electron transfer (ET) from the porphyrin to the fullerene prevails in polar solvents. Complexation of [Zn(tpp)] by the fullerene derivative is reversible and, following excitation of the [Zn(tpp)], gives rise to very efficient charge separation. In fluid polar solvents such as THF and benzonitrile, radical-ion pairs (RPs) are generated both by intramolecular ET inside the complex and by intermolecular ET in the uncomplexed form. Charge-separated states have lifetimes of about 10 micros in THF and several hundred of microseconds in benzonitrile at room temperature.

Carbon↗
PubMed2001

Fullerene-based amino acids and peptides.

Recent advances in the chemistry of fullerene have allowed the synthesis of many classes of novel fullerene derivatives. Among these classes, fullerene-based amino acids and peptides are particularly interesting, both for structural studies and biological applications. In this review, we will discuss our own achievements in this rapidly growing field. In particular, the application of fulleroproline (Fpr) amino acids and peptides to medicinal chemistry and material science will be highlighted.

Amino Acids↗
PubMed2001

DNA-photocleavage agents.

This review describes recent advances in the development of DNA-photocleavage agents. Major mechanisms of photosensitized DNA photocleavage are presented and the most popular categories of compounds are considered, which include metal complexes and many organic functional derivatives. DNA-targeted conjugates of photosensitizers are also described and discussed.

Base Sequence↗
PubMed2000

Additions of Azomethine Ylides to Fullerene C(60) Assisted by a Removable Anchor.

The addition of nitrile oxides to [60]fullerene, leading to isoxazolinofullerenes, can be reversed using reducing agents such as Mo(CO)(6) or DIBALH. Thus, this reaction can be used, in principle, for protection/deprotection of [60]fullerene or for solubilization purposes. The tether-controlled tandem addition of nitrile oxides and azomethine ylides provides mainly cis-1 patterns. The determination of the structure of bisadducts was obtained by NMR spectroscopy with the help of HMQC, HMBC, and NOEDS techniques. The isoxazoline moiety could be removed using Mo(CO)(6) leaving a fulleropyrrolidine derivative.

Journal Article↗
PubMed2000

Antimycobacterial activity of ionic fullerene derivatives.

Positively charged fullerene derivatives, moderately soluble in water:DMSO 9:1, have been tested using three strains of Mycobacterium spp. Some compounds inhibit the growth of Mycobacterium tuberculosis, a human clinical isolate, particularly virulent and resistant, at doses as low as 5 microg/mL.

Anti-Bacterial Agents↗
PubMed2000

Excited-state properties of C(60) fullerene derivatives.

This Account reviews our main achievements in the field of excited-state properties of fullerene derivatives. The photosensitizing and electron-acceptor features of some relevant classes of functionalized fullerene materials are highlighted, considering the impact of functionalization on fullerene characteristics. In addition, the unique optimization in terms of redox potentials, water-solubility, and singlet oxygen generation is presented for several novel fullerene-based materials.

Carbon↗
PubMed1998

Noninvasive mechanical ventilation in the weaning of patients with respiratory failure due to chronic obstructive pulmonary disease. A randomized, controlled trial.

BACKGROUND: In patients with acute exacerbations of chronic obstructive pulmonary disease, mechanical ventilation is often needed. The rate of weaning failure is high in these patients, and prolonged mechanical ventilation increases intubation-associated complications. OBJECTIVE: To determine whether noninvasive ventilation improves the outcome of weaning from invasive mechanical ventilation. DESIGN: Multicenter, randomized trial. SETTING: Three respiratory intensive care units. PATIENTS: Intubated patients with chronic obstructive pulmonary disease and acute hypercapnic respiratory failure. INTERVENTION: A T-piece weaning trial was attempted 48 hours after intubation. If this failed, two methods of weaning were compared: 1) extubation and application of noninvasive pressure support ventilation by face mask and 2) invasive pressure support ventilation by an endotracheal tube. MEASUREMENTS: Arterial blood gases, duration of mechanical ventilation, time in the intensive care unit, occurrence of nosocomial pneumonia, and survival at 60 days. RESULTS: At admission, all patients had severe hypercapnic respiratory failure (mean pH, 7.18+/-0.06; mean PaCO2, 94.2+/-24.2 mm Hg), sensory impairment, and similar clinical characteristics. At 60 days, 22 of 25 patients (88%) who were ventilated noninvasively were successfully weaned compared with 17 of 25 patients (68%) who were ventilated invasively. The mean duration of mechanical ventilation was 16.6+/-11.8 days for the invasive ventilation group and 10.2+/-6.8 days for the noninvasive ventilation group (P = 0.021). Among patients who received noninvasive ventilation, the probability of survival and weaning during ventilation was higher (P = 0.002) and time in the intensive care unit was shorter (15.1+/-5.4 days compared with 24.0+/-13.7 days for patients who received invasive ventilation; P = 0.005). Survival rates at 60 days differed (92% for patients who received noninvasive ventilation and 72% for patients who received invasive ventilation; P = 0.009). None of the patients weaned noninvasively developed nosocomial pneumonia, whereas 7 patients weaned invasively did. CONCLUSIONS: Noninvasive pressure support ventilation during weaning reduces weaning time, shortens the time in the intensive care unit, decreases the incidence of nosocomial pneumonia, and improves 60-day survival rates.

Aged↗
PubMed1998

Trans-cis amide bond isomerization in fulleroprolines.

The 1H NMR study of fulleroproline derivative Ac-Fpr-OtBu and its Pro analogue Ac-L-Pro-OtBu over a range of temperatures in toluene-d8 solution has enabled the comparison of their equilibrium and activation parameters for the trans/cis interconversion around the amide partial double bond.

Bacterial Proteins↗
PubMed1997

Beta-turn induction by C60-based fulleroproline: synthesis and conformational characterization of Fpr/Pro small peptides.

We have recently described the preparation of Fpr (C60-based fulleroproline). In this paper the synthesis and a conformational characterization of heterochiral di- and tripeptides containing this new alpha-amino acid are reported. A folded structure, induced by the -L-Fpr-D-Ala-sequence in chloroform solution and detected by Fourier transform infrared absorption and 1H nuclear magnetic resonance, has been compared with the known propensity of the cognate -L-Pro-D-Ala-sequence to adopt a beta II-turn conformation, which has also been confirmed in this work. The beta II-turn structure is retained in the crystal state by the Pro-peptides, as shown by the X-ray diffraction structures of Ibu-L-Pro-D-Ala-NHtBu and Z-L-Pro-D-Ala-L-Ala-OtBu.

Bacterial Proteins↗