Improved Process for the Continuous Acylation of 1,3-Benzodioxole.

The acylation of 1,3-benzodioxole was studied in a continuous process using a recyclable heterogeneous substoichiometric catalyst. In a short time period (30 min), at 100 °C, the conversion rate was 73%, with a selectivity of 62% of the desired acylated product; the reaction was run continuously for 6 h, showing excellent stability and selectivity. Moreover, the unreacted starting material, 1,3-benzodioxole, can be easily separated by distillation and recycled.

Fast determination of extra-virgin olive oil acidity by voltammetry and Partial Least Squares regression.

In this paper, an approach for the detection of extra-virgin olive oil (EVOO) free-acidity, based on combination of voltammetric profiles (Voltammetry) and Partial Least Squares (PLS) multivariate regression, is described. Voltammetric measurements are performed with a 12.5 µm radius platinum microdisk, directly in the oil samples mixed with 0.5 M of the room temperature ionic liquid (RTIL) tri-hexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, which acted as a supporting electrolyte, and allows achieving a suitable conductivity in the matrices. Multivariate regression is performed directly on full voltammetric responses recorded over a properly chosen negative potential range and scan rate, where essentially all free fatty acids, characterizing EVOOs, can be reproducibly reduced. PLS regression models are built by employing Italian EVOO samples training sets at different acidity levels (over the range 0.2% w/w - 1.5% w/w; (% w/w) represents mass percentage) and optimized by choosing the optimal complexity, in terms of number of latent variables (LVs). The free-acidity prediction is made through a multivariate model, constructed by using standards of known acidity (determined by the official volumetric titration method) and validated on an external sample set. To show the validity of the proposed method, the PLS/Voltammetry predictions of the free-acidity of a series of commercially available Italian EVOOs, ranging from 0.2 to 0.41 %w/w, are obtained and the values compared with those determined by the official titration approach. Differences found between the two methods are within 5% RSD.

Plasma Activation of Copper Nanowires Arrays for Electrocatalytic Sensing of Nitrate in Food and Water.

Electrochemical methods for nitrate detection are very attractive since they are suitable for in-field and decentralized monitoring. Copper electrodes are often used to this aim as this metal presents interesting electrocatalytic properties towards nitrate reduction. In this research, we study improvements in the electrochemical analysis of nitrate in natural water and food by taking advantage of the detection capabilities of ensembles of copper nanowire electrodes (CuWNEEs). These electrodes are prepared via template electrodeposition of copper within the nanopores of track-etched polycarbonate (PC) membranes. A critical step in the preparation of these sensors is the removal of the template. Here, we applied the combination of chemical etching with atmospheric plasma cleaning which proved suitable for improving the performance of the nanostructured copper electrode. Analytical results obtained with the CuWNEE sensor for nitrate analyses in river water samples compare satisfactorily with those achieved by standard chromatographic or spectroscopic methods. Experimental results concerning the application of the CuWNEEs for nitrate analysis in food samples are also presented and discussed, with focus on nitrate detection in leafy vegetables.

Photoprotective characteristics of natural antioxidant polyphenols.

Fourteen natural polyphenols belonging to the classes of stilbenes, flavonoids and hydroxycinnamic acid derivatives, have been investigated in order to verify the combination of their photoprotective characteristics with their antioxidant properties. To this purpose, sun protection factor (SPF), UVA/UVB ratio and critical wavelengths (λc), have been considered to evaluate photoprotection capacity, while inhibition of lipid peroxidation has been adopted as a reliable measure of the antioxidant properties. The results obtained indicate that a large number of these natural phenol derivatives show both antioxidant activity and photoprotective characteristics and, as a consequence, they could be interesting components for pharma-photoprotection formulations. In fact, these compounds associate to a preventive function, linked to UV filtering properties, an effective action, correlated to antioxidant capacity of contrast towards UV-induced ROS injury.

Antioxidant properties of Brazilian tropical fruits by correlation between different assays.

Four different assays (the Folin-Ciocalteu, DPPH, enzymatic method, and inhibitory activity on lipid peroxidation) based on radically different physicochemical principles and normally used to determine the antioxidant activity of food have been confronted and utilized to investigate the antioxidant activity of fruits originated from Brazil, with particular attention to more exotic and less-studied species (jurubeba, Solanum paniculatum; pequi, Caryocar brasiliense; pitaya, Hylocereus undatus; siriguela, Spondias purpurea; umbu, Spondias tuberosa) in order to (i) verify the correlations between results obtained by the different assays, with the final purpose to obtain more reliable results avoiding possible measuring-method linked mistakes and (ii) individuate the more active fruit species. As expected, the different methods give different responses, depending on the specific assay reaction. Anyhow all results indicate high antioxidant properties for siriguela and jurubeba and poor values for pitaya, umbu, and pequi. Considering that no marked difference of ascorbic acid content has been detected among the different fruits, experimental data suggest that antioxidant activities of the investigated Brazilian fruits are poorly correlated with this molecule, principally depending on their total polyphenolic content.

Propolis as potential cosmeceutical sunscreen agent for its combined photoprotective and antioxidant properties.

Propolis, bee glue, and its main polyphenolic components show high antioxidant activity as found measuring their inhibitory action on lipid peroxidation of linoleic acid (LA) in sodium dodecyl sulfate (SDS) micelles. Furthermore, these substances evidence effectiveness as broad spectrum UVB and UVA photoprotection sunscreens, as it results by measurements of sun protection factor (SPF), the universal indicator related primarily to UVB radiations, and of the two parameters giving an indication of the UVA absorbance properties, i.e. UVA/UVB ratio and critical wavelength. The combination of these characteristics moves up propolis and its main polyphenolic components to the class of cosmeceuticals, as possible active ingredient of sunscreen commercial formulations for their protective and preventive properties.

Antioxidant properties of resveratrol and piceid on lipid peroxidation in micelles and monolamellar liposomes.

The antioxidant activities of trans-resveratrol (trans-3,5,4'-trihydroxystilbene) and trans-piceid (trans-5,4'-dihydroxystilbene-3-O-beta-D-glucopyranoside), its more widespread glycosilate derivative, have been compared measuring their inhibitory action on peroxidation of linoleic acid (LA) and the radical scavenging ability towards different free radicals (such as DPPH) and radical initiators. It has been found that the two stilbenes have similar antioxidant capacity, while the comparison with BHT (2,6-di-tert-butyl-4-methylphenol) and alpha-tocopherol (vitamin E, vit. E), taken as reference, points out a slower but prolonged protective action against lipid peroxidation. Furthermore, piceid appears more efficacious than resveratrol as a consequence of the reaction of the latter with its radical form. The DSC profiles of phosphatidylcholine liposomes of various chain lengths, and EPR measurements of spin labelled liposomes demonstrated that the susceptible hydroxyl group of these compounds are located in the lipid region of the bilayer close to the double bonds of polyunsaturated fatty acids, making these stilbenes particularly suitable for the prevention and control of the lipid peroxidation of the membranes.

Interaction of isopropylthioxanthone with phospholipid liposomes.

Isopropylthioxanthone (ITX) is a highly lipophilic molecule which can be released in foods and beverages from the packages, where it is present as photoinitiator of inks in printing processes. Recently it was found in babies milk, and its toxicity cannot be excluded. The structure of the molecule suggests a possible strong interaction with the lipid moiety of biological membranes, and this is the first study of its effects on phospholipid organization, using differential scanning calorimetry (DSC) and spin labelling techniques. The data obtained with multilamellar liposomes of saturated phospholipids of different length, with and without cholesterol, point out that the molecule changes the lipid structure; in particular, in the gel state, behaving like a disordering agent it increases the mobility of the bilayer, while, in the fluid state, tends to rigidify the membrane, in a cholesterol like way. This behavior supports the hypothesis that ITX experiences a relocation process when the lipid matrix passes from the gel to the fluid state.

Interaction of fluoxetine with phosphatidylcholine liposomes.

Fluoxetine (Prozac) is one of the latest of a new generation of antidepressants, approved by FDA in 2002. The interactions of fluoxetine with multilamellar liposomes of pure phosphatidylcholine (PC) or containing cholesterol 10% molar were studied as a function of the lipid chain lengths, using differential scanning calorimetry and spin labelling EPR techniques. The DSC profiles of the gel-to-fluid state transition of liposomes of DMPC (C14:0) are broadened and shifted towards lower temperatures at increasing dopant concentrations and, with less than 10% fluoxetine, any detectable transition is destroyed. The broadened profiles and the lowered transition temperatures demonstrate that both the size and the packing of the cooperative units undergoing the transition are modified by fluoxetine, leading to a looser and more flexible bilayer. No phase separation was observed. The effects of fluoxetine on the thermotropic phase behaviour of DPPC (C16:0) and, even more, of DSPC (C18:0) are different from that of DMPC. In fact, in the former cases, two peaks appeared at increasing dopant concentrations, suggesting the occurrence of a phase separation phenomenon, which is a sign of a binding of fluoxetine in the phosphate region. In cholesterol containing membranes, fluoxetine, even at low concentrations, leads to a general corruption of the membrane, both in terms of packing and cooperativity, and the formation of any new phase is no longer observable. EPR spectra reflect the disordered motion of acyl chains in the bilayer. It was found that fluoxetine lowers the order of the lipid chains mainly in correspondence of the fifth carbon position of SASL, indicating a possible accumulation near the interfacial region.

New enzymatic method for the determination of total phenolic content in tea and wine.

A new spectrophotometric enzymatic method for the determination of total phenol content in tea and wine has been developed. The method is based on the peroxidase-catalyzed oxidation, by hydrogen peroxide, of phenols to phenoxyl radicals, which can react with aromatic substrates to form intensely colored adducts. In comparison with the widely used Folin-Ciocalteu method, this method appears to be more specific and more rapid and as a whole is not affected by the common interfering substances such as ascorbate, citrate, and sulfite. Numerous samples of teas and wines were analyzed by using the new method, and the results compared with those obtained by using the Folin and scavenging of DPPH methods. The differences of the total phenols content found by applying the three methods are discussed in terms of the different specificities of the analytical basis.

Evaluation of the antioxidant properties of propofol and its nitrosoderivative. comparison with homologue substituted phenols.

Propofol (2,6-diisopropylphenol), some substituted phenols (2,6-dimethylphenol and 2,6-ditertbutylphenol) and their 4-nitrosoderivatives have been compared for their scavenging ability towards 1,1-diphenyl-2-picrylhydrazyl and for their inhibitory action on lipid peroxidation. These products were also compared to the classical antioxidants butylated hydroxytoluene and butylated hydroxyanisole. When measuring the reactivity of the various phenolic derivatives with 1,1-diphenyl-2-picrylhydrazyl the following order of effectiveness was observed: butylated hydroxyanisole > propofol > 2,6-dimethylphenol > 2,6-di-tertbutylphenol > butylated hydroxytoluene. In cumene hydroperoxide-dependent microsomal lipid peroxidation, propofol acts as the most effective antioxidant, while butylated hydroxyanisole, 2,6-di-tertbutylphenol and butylated hydroxytoluene exhibit a rather similar effect, although lower than propofol. In the iron/ascorbate-dependent lipid peroxidation propofol, at concentrations higher than 10 microM, exhibits antioxidant properties comparable to those of butylated hydroxytoluene and butylated hydroxyanisole, 2,6-Dimethylphenol is scarcely effective in both lipoperoxidative systems. The antioxidant properties of the various molecules depend on their hydrophobic characteristics and on the steric and electronic effects of their substituents. However, the introduction of the nitroso group in the 4-position almost completely removes the antioxidant properties of the examined compounds. The nitrosation of the aromatic ring of antioxidant molecules and the consequent loss of antioxidant capacity can be considered a condition potentially occurring in vivo since nitric oxide and its derivatives are continuously formed in biological systems.

Correlation between fluidising effects on phospholipid membranes and mitochondrial respiration of propofol and p-nitrosophenol homologues.

Nitrosopropofol (2-6-diisopropyl-4-nitrosophenol) has dramatic consequences for respiration, ATP synthesis and the transmembrane potential of isolated rat liver mitochondria at concentrations at which propofol (2-6-diisopropylphenol) does not cause any apparent effects. These results correlate well with the observation that nitrosopropofol is also a stronger perturbing agent of phospholipid membranes. In this paper we verify the possible biological activity of different phenols and nitrosophenols on mitochondrial respiration. We then discuss their interactions with phospholipid liposomes, studied with differential scanning calorimetry, spin labelling techniques and UV-Vis spectrophotometry, in order to obtain information on drug distribution and the modifications they impose on lipid bilayer. The results of the experiments performed on mitochondria and model membranes prove an interesting correlation between the effects of the molecules on both systems.

Different effects of propofol and nitrosopropofol on DMPC multilamellar liposomes.

The mechanisms of reaction of propofol with nitrosoglutathione lead to the formation of an active species which was identified, and then synthesised, as 2,6-diisopropyl-4-nitrosophenol. In the present work, we demonstrate the in vitro formation of 2,6-diisopropyl-4-nitrosophenol, then we discuss the interaction of propofol and 2,6-diisopropyl-4-nitrosophenol with dimyristoylphosphatidylcholine and egg yolk phosphatidylcholine multilamellar liposomes using differential scanning calorimetry and spin labelling techniques. It was demonstrated that both molecules are highly lipophylic and absorb almost entirely in the lipid phase. The thermotropic profiles showed that these molecules affect the temperature and the co-operativity of the gel-to-fluid state transition of the liposomes differently: the effects of 2,6-diisopropylphenol on the lipid organisation are quite similar to phenol and coherently interpretable in terms of the disorder produced in the membrane by a bulky group; 2,6-diisopropyl-4-nitrosophenol is a stronger perturbing agent, and ESR spectra suggest that this is due to a relative accumulation of the molecule into the interfacial region of the bilayer.