Photostability of Octyl‐P‐Methoxy Cinnamate in O/W Emulsions and in SLNs Vehicled in the Emulsions

The photochemical degradation of the sunscreen p‐octyl‐methoxy‐cinnamate (OMC) was studied in different media: Finsolv TN (a fluid ester), O/W emulsion and gel‐emulsion. OMC photolysis was performed using an UVB lamp and the degradation kinetic was studied in presence of various initial concentration of the active. The study was performed comparing the naked to the SLNs form of the active and the experiments were monitored with HPLC/UV‐VIS apparatus. Results suggest that lower is the concentration of the UVB sunscreen in the formulations more pronounced is its photodegradation rate. In all the cases the inglobation of OMC into SLNs leads to an over additive UV‐blocking effect.     

Rheological Characterization of Hydrophylic Gels

Rheological characteristics of gels were studied, with the focus on their use as a cosmetic base. Some ideal characteristics can be predicted by the rheological characterization, such as the performance, with easy application and without dripping or forming lumps and bubbles. Moreover, it is possible to detect signs of physical instability. The gels were prepared with sodium carboxymethyl cellulose 3% and 5%, with Carbopol 940 (INCI: Carbomer) and with Carbopol Ultrez (INCI: Acrylates/C10-30 alkyl acrylate crosspolymer). The tests performed were yield stress, stress sweep and creep and recovery. The gel with 3% of sodium carboxymethyl cellulose presented the most appropriated behavior and can be indicated as the most suitable cosmetic base.     

Physicochemical and Biochemical Profiling of Diphenyl Diselenide

The objective of the present study was to evaluate the physicochemical and biochemical profiling of diphenyl diselenide (PhSe)₂, a selenoorganic compound with biological activity. Experimental protocols were established for chemical stability in isotonic phosphate buffer (PBS) pH 7.4 and in simulated gastric and intestinal fluids, biological stability (bovine serum albumin (BSA) and plasma), solubility in PBS pH 7.4, distribution coefficient (Log D) in octanol/PBS, and determination of free (PhSe)₂ concentrations in BSA and plasma by using liquid chromatography with ultraviolet detection and tandem mass spectrometry. (PhSe)₂ was found to be chemically stable and not susceptible to degradation in plasma. The aqueous solubility was 0.98?±?0.072 μM and the Log D in octanol/PBS system was found to be 3.13. The percentage of unbound fractions of (PhSe)₂ obtained by equilibrium dialysis from BSA and plasma incubated with 100 μM (PhSe)₂ were 0.69?±?0.12 and 0.44?±?0.09 %, respectively. The findings indicated that (PhSe)₂ presents chemical and biological stability. Though, the compound showed low aqueous solubility, high Log D value and high binding to plasmatic protein. These data contribute to the knowledge of the toxicokinetic properties of (PhSe)₂ and further explain its low bioavailability in experimental models.     

Hydroxypropyl-β-cyclodextrin-based extraction for diuron bioaccessibility in an artificially contaminated soil

Different extraction techniques are presented here to determine whether their extraction abilities correlate with the bioaccessible diuron fraction in an aged contaminated soil. Diuron bioaccessibility was tested establishing correlations between the amount of diuron biodegraded after different aging periods, using a specific diuron biodegrader microorganism consortium, and the amount of diuron extracted by 50 mM hydroxypropyl-β-cyclodextrin (HPBCD), 10 mM CaCl₂, hexane, or butanol. HPBCD extraction procedure correlated better than the other extraction techniques tested with diuron measured microbial biodegradation for all aging times (1, 30, 60, 90, and 120 days). The results obtained with this soil indicate that the aqueous HPBCD extraction technique has potential to become a valuable tool for estimating the bioaccessible fraction of soil-associated diuron at different aging times, and it could be applicable in the assessment of risk and contaminated land bioremediation potential.     

Chemical Synthesis of N-Aryl Glycosides

Along with the O- and C-aryl glycosides, N-aryl glycosides represent an important class of carbohydrate and heterocyclic aryl conjugates that possess diverse applications and implications of biological interest. However, most of the synthetic efforts have been directed toward the preparation of O- and C-aryl glycosides. This review focuses on the various strategies that have been employed to synthesize N-aryl glycosides, most of which developed in the past 20 years. Besides having their unique applications, these N-aryl glycosides can also be treated as the analogs of O- and C-aryl glycosides. Wide ranges of reaction conditions are discussed for the optimum conditions.     

Chromogenic azole diazothiacrown ethers

Azocrown ethers with sulphur atoms and pyrrole or imidazole residue as a part of macrocycle have been synthesised. Their metal complexation abilities in acetonitrile were studied using UV–vis spectrophotometry. The largest spectral changes were observed for both pyrrole- and imidazole-azothiacrown ethers on complexation with Pb^2 + , Cu^2 + , Zn^2 + , Ni^2 + , Co^2 +  and Ag⁺ ions. In the case of alkali and alkaline earth metal ions no spectral changes were found. Preliminary studies of ion-selective membrane electrodes with synthesised ionophores are presented. In the measurement for transition/heavy metal cations, only copper and lead give high responses. X-ray structure of 18-membered pyrrole azothiacrown ether is described.     

Synthesis of Multivalent Carbohydrate‐Centered Glycoclusters as Nanomolar Ligands of the Bacterial Lectin LecA from Pseudomonas aeruginosa

A family of fifteen glycoclusters based on a cyclic oligo‐(1→6)‐β‐D ‐glucosamine core has been designed as potential inhibitors of the bacterial lectin LecA with various valencies (from 2 to 4) and linkers. Evaluation of their binding properties towards LecA has been performed by a combination of hemagglutination inhibition assays (HIA), enzyme‐linked lectin assays (ELLA), and isothermal titration microcalorimetry (ITC). Divalent ligands displayed dissociation constants in the sub‐micromolar range and tetravalent ligands displayed low nanomolar affinities for this lectin. The influence of the linker could also be demonstrated; aromatic moieties are the best scaffolds for binding to the lectin. The affinities observed in vitro were then correlated with molecular models to rationalize the possible binding modes of these glycoclusters with the bacterial lectin.     

Structure and energetic properties of 1,5-dinitrobiuret

The two-dimensional potential energy scan shows that the pseudo-trans conformer of 1,5-dinitrobiuret (DNB) is the most stable form of isolated molecule, while the pseudo-cis conformer is about 7.5 kJ/mol higher in energy. Thus, the structure of gaseous DNB is different from that in crystal state, where the molecules have pseudo-cis conformation. The value of enthalpy of formation of gaseous DNB (?257 ± 5 kJ/mol) is calculated from isodesmic reactions using G4 energies. Combining this value with empirically estimated enthalpy of sublimation, the enthalpy of formation of crystal DNB is predicted to be ?415 ± 15 kJ/mol. The bond dissociation enthalpies are calculated for all bonds. The energy of the weakest N–NO₂ bonds is equal to 190–200 kJ/mol. Similar calculations were carried out for biuret. The gaseous biuret exists predominantly in the pseudo-trans form. The calculated enthalpy of formation of gaseous biuret agrees well with the experimental one. The correlation of calculated bond energies with corresponding bond distances and electron density is discussed for biuret and DNB.