In vitro antioxidant and in vivo photoprotective effects of an association of bioflavonoids with liposoluble vitamins

A new tendency in cosmetic formulations is the association of botanical extracts and vitamins to improve skin conditions by synergic effects. The objective of this study was to determine the antioxidant activity of associated bioflavonoids, retinyl palmitate (RP), tocopheryl acetate (TA) and ascorbyl tetraisopalmitate (ATIP), as well as their photoprotective effects in preventing increased erythema, transepidermal water loss (TEWL) and sunburn cell formation in hairless mouse skin. The antioxidant activity of solutions containing the association or each substance separately was evaluated in vitro by a chemiluminescence assay. The photoprotective effect was evaluated by means of in vivo tests. Dorsal skin of hairless mice was treated daily by topical applications for 5 days with formulations containing or not containing (vehicle) the flavonoid-vitamins association (5%). The skin was irradiated (UVA/B) 15 minutes after the last application. The results showed that bioflavonoids had in vitro antioxidant properties and also that when they were associated with vitamins their antioxidant activity was more pronounced. On the other hand, erythema and UV damage to the permeability barrier function (TEWL) was not significantly reduced by previous treatment with the flavonoid-vitamin-association formulations, when compared to the irradiated vehicle-treated area. However, the treatment protected the skin from UV damage because it reduced the number of sunburn cells, when compared to the vehicle-treated area. Finally, the association of vitamins and bioflavonoids added to a dermocosmetic formulation showed a relevant biological activity in terms of photoprotection, because the association of bioflavonoids and vitamins acted by different mechanisms, such as antioxidation and absorption of UV radiation, which suggests its use in antiaging and photoprotective products.     

Influence of the photostabilizer in the photoprotective effects of a formulation containing UV-filters and vitamin A

Vitamin A palmitate has been used in cosmetics; however, studies report that this substance shows photoreactivity that can lead to loss of safety and efficacy. On the other hand, photostabilizers have been used to increase sunscreen photostability and consequently their safety and effectiveness. Thus, this study aimed to evaluate the influence of photostabilizers on the photoprotective effects of a cosmetic formulation containing UV-filters and vitamin A palmitate. The formulation containing UV-filters was supplemented with vitamin A palmitate and the photostabilizers diethylhexyl 2,6-naphthalate (DEHN), bumetrizole and benzotriazolyl dodecyl p-cresol (BTDC). Hairless mice were treated daily by topical applications and irradiated (UVA/B). Erythema index, transepidermal water loss, histological/histometric analysis and number of sunburn cells (SBC) were evaluated. The results showed that all formulations protected from UV-induced enhancement of erythema and SBC but there was no difference among them. The formulation with no stabilizers reduced viable epidermis thickness due to atrophy induced by UV radiation. Thus, it can be concluded that the presence of photostabilizers influenced the effects of formulations containing UV-filters and vitamin A palmitate, which could be seen by histological and histometric analysis. Furthermore, the formulations containing the stabilizers DEHN and BTDC showed better protective effects on hairless mice skin.     

Radiation grafting of NIPAAm and acryloxysuccinimide onto PP films and sequent crosslinking with polylysine

N-isopropylacrylamide (NIPAAm) and N-acryloxysuccinimide (NAS) were grafted from their binary mixtures in tetrahydrofurane (THF) and toluene solutions onto polypropylene (PP) films by the pre-irradiation oxidative method in air. Effects of pre-irradiation dose, dose rate, and monomer concentrations (NAS/NIPAAm) were studied. The grafted copolymers exhibited the lower critical solution temperature (LCST) at around 31 °C. Based on its thermo-reversible behavior, this system has been used for immunoassay, drug delivery, separation processes and immobilization of enzymes. N-acryloxysuccinimide (NAS) has been used as an active ester to bind proteins through amide bond formation with lysine, and because of this property, the grafted copolymer has been crosslinked with polylysine. Techniques used to characterize the films included differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), infrared (FTIR-ATR) and elemental analysis. Results on thermo-sensitivity are presented. This new system could find applications in vesicle immobilizations.     

Headspace single-drop microextraction for the analysis of chlorobenzenes in water samples

Exposing a microlitre organic solvent drop to the headspace of an aqueous sample contaminated with ten chlorobenzene compounds proved to be an excellent preconcentration method for headspace analysis by gas chromatography-mass spectrometry (GC-MS). The proposed headspace single-drop microextraction (SDME) method was initially optimised and the optimum experimental conditions found were: 2.5 microl toluene microdrop exposed for 5 min to the headspace of a 10 ml aqueous sample containing 30% (w/v) NaCl placed in 15 ml vial and stirred at 1000 rpm. The calculated calibration curves gave a high level of linearity for all target analytes with correlation coefficients ranging between 0.9901 and 0.9971, except for hexachlorobenzene where the correlation coefficient was found to be 0.9886. The repeatability of the proposed method, expressed as relative standard deviation varied between 2.1 and 13.2% (n = 5). The limits of detection ranged between 0.003 and 0.031 microg/l using GC-MS with selective ion monitoring. Analysis of spiked tap and well water samples revealed that matrix had little effect on extraction. A comparative study was performed between the proposed method, headspace solid-phase microextraction (SPME), solid-phase extraction (SPE) and EPA method 8121. Overall, headspace SDME proved to be a rapid, simple and sensitive technique for the analysis of chlorobenzenes in water samples, representing an excellent alternative to traditional and other, recently introduced, methods.     

Donor/acceptor organotriiron(II) hydrazone chromophores: structural, spectroscopic and electrochemical properties

Two new trinuclear organoiron(II) complexes, in which a trans-1,2-ferrocenyl-ferrocenylene ethene unit (electron-donors) is attached to an electron-deficient cationic mixed sandwich via a conjugated hydrazone bridge, giving complexes of the type , have been prepared. The complexes were fully characterised by ¹H NMR, IR, UV-Vis spectroscopy. Their electrochemical properties have been studied by means of cyclic voltammetry, showing an effective electronic coupling between the two ferrocenyl fragments. The X-ray crystal structure of compound shows that it adopts the sterically more hindered syn-conformation about the 1,1′-ferrocenediyl core, with a parallel disposition of the conjugated dinucleating ligands, therefore, favouring an efficient electron delocalization through the entire π-framework. At the same time, the (C₅-ring)Fe moieties adopt an anti,anti-conformation with the iron atoms on the opposite faces of their respective bridging ligand.     

Cyclic vinyl p-tolyl sulfilimines as chiral dienophiles: theoretical study on the stereoselectivity, Lewis acid catalysis, and solvent effects in their Diels-Alder reactions

The theoretical study reported in the present work deals with chiral cyclic vinyl sulfilimines and their reactivity as dienophiles in [4 + 2] cycloaddition reactions, using B3LYP/6-31G(d)//AM1 and B3LYP/6-31G(d)//B3LYP/6-31G(d) model chemistries. Consideration of Lewis acid catalysis, illustrated by BF(3), decreases the activation energies of the cycloaddition process while the charge transfer from the diene to the sulfilimine is augmented. The [4 + 2] cycloaddition reactions of sulfilimines with both furan and cyclopentadiene occur in the gas phase with endo stereoselectivity, which is more pronounced with the latter diene. Endo-exo energy differences in the gas phase with the B3LYP/6-31+G(d)//B3LYP/6-31+G(d), B3LYP/6-31G(d)//B3LYP/6-31G(d), and B3LYP/6-31G(d)//AM1 model chemistries are almost the same. Solvent effects are responsible for the inversion of the stereoselectivity in the reactions of sulfilimines with furan because of the great difference in the dipole moments in endo and exo approaches.     

Simultaneous determination of volatile and semi-volatile aromatic hydrocarbons in virgin olive oil by headspace solid-phase microextraction coupled to gas chromatography/mass spectrometry

A reliable, simple and relatively fast method for the simultaneous determination of volatile and semi-volatile aromatic hydrocarbons in virgin olive oil was developed, based on headspace solid-phase microextraction (HS-SPME). The investigation regarded eco-contaminants such as alkylated monoaromatic hydrocarbons from C1- to C4-benzenes and light polyaromatic hydrocarbons up to four aromatic rings. Sampling and chromatographic conditions were optimized by using standard solutions in deodorized olive oil and the analytical performances of the method were determined. The proposed method was then applied to real samples of virgin olive oil were the target hydrocarbons could be identified and quantified. Several of them had not been previously quantified in virgin olive oil. Moreover, by the analysis of olive oil samples an additional number of C4-benzenes could be tentatively identified.     

Separation of the high-ceiling diuretic Torasemide and its metabolites by capillary zone electrophoresis with diode-array detection

A capillary zone electrophoretic method was developed for the separation of the high-ceiling loop diuretic Torasemide and three of its metabolites (M1, M3 and M5) using an experimental design approach. Two different experimental designs were employed to optimize the developed method: (i) a fractional factorial design examining six factors at two levels (2(6-2)) and (ii) a central composite design examining two factors at two levels (2(2)+2x2+p). The factors studied were: pH, buffer concentration, proportion of boric acid in the mixed boric acid:potassium dihydrogen phosphate background electrolyte, temperature, applied voltage and percentage of organic modifier. Resolution between peaks was established as response. Separation of the four studied compounds was achieved in less than 8 min, using an electrolyte of 20 mM boric acid:potassium dihydrogen phosphate (75:25 v/v) with 15% MeOH adjusted to pH 9.7 with KOH, at a potential of 28 kV. Detection wavelength and temperature were 206 nm and 35 degrees C, respectively.     

Study of the Ternary Complex Formation between Vanadium(III)-Cysteine and Small Blood Serum Bioligands

The complex species formed between vanadium(III) cysteine and small blood serum bioligands: lactic, oxalic, citric and phosphoric acids were studied in aqueous solution by means of electromotive force measurements, Emf(H), at 25 °C and 3.0 mol⋅dm⁻³ KCl as the ionic medium. The ternary complexes were studied by potentiometric measurements and the data analyzed using the least-squares computational program LETAGROP to obtain the respective stability constants and stoichiometric coefficients. The UV-Vis spectrophotometric measurements were done in order to make a qualitative characterization of the complexes formed in aqueous solution.