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.     

Interactions between polyamines and nucleotides studied by31P and1H NMR

The formation of complexes between poly- and mono-amines and some polyphosphate molecules such as ATP, ADP and tripolyphosphate was studied by³¹P and¹H NMR. Evidence for formation of complexes was obtained by¹H NMR, while the values of dissociation constants of the complexes between nucleotides and spermine and spermidine, calculated from the shift of the³¹P NMR, were in mM range.     

Studies on pyrrolidinones. Synthesis of methyl N-(4-nitrobenzyl)pyroglutamate

Methyl N-trimethylsilylpyroglutamate is reacted with 4-nitrobenzyl chloride to yield methyl N-(4-nitrobenzyl)pyroglutamate.     

Influence of growth parameters on the interface abruptness in CBE-grown InGaAs/InP QWs and SLs

A simple thermodynamic model for As and P incorporation at the CBE-grown InGaAs/InP and InP/InGaAs interfaces has been developed. This model agrees with the X-ray diffraction and the photoluminescence features experimentally obtained from high-quality single quantum wells (SQWs) and multi-quantum wells (MQWs). Our experimental results compare well with the best published data and clearly show that monolayer interfaces can be obtained in this material system only by chosing the proper growth interruption (GI) conditions and accepting a strong mismatch at each interface. This effect could become dramatic in superlattice structures in which the QW period is smaller than 5 nm and the resulting strain could lead to poor crystal quality and optical properties.     

Synthesis and NMR analysis of 2,4-dichloro-1-pentene and of 2,4-dichloro-1-pentene-1-d1

The compound 2,4-dichloro-1-pentene-1-d₁ ( 1 ) was synthesized starting from and CH?CNa. In the last stage of the synthesis on activated carbon-HgCl₂ catalyst), ( 3 ) were formed together with ( 1 ). The NMR parameters of ( 1 ), its cis and trans isomers and ( 2 ) were obtained in C₆D₆ solution at 100 MHz. Theoretical spectra of ( 1 ) at 60 MHz were simulated with the aid of a computer, using as input the NMR parameters obtained at 100 MHz and good agreement with the experiment was obtained.     

Studies on pyrrolidinones. synthesis of fused 1,5-naphthyridines

The synthesis of new condensed indolizinediones derived from pyroglutamic acid is described. The Semmler–Wolff transposition of the oxime of these ketones leads to fused dihydro-1,5-naphthyridinones. Easy introduction of side amino chains indicates that potential DNA-intercalating heterocyclic systems fused on 1,5-naphthyridine nucleus could be obtained in these series.     

Studies on pyrrolidinones. A convenient synthesis of 5-cyano-2-pyrrolidinone derivatives

The reaction of 2-pyrrolidinone-5-carboxamide (pyroglutamide) with trimethylchlorosilane and zinc chloride as a catalyst afford in one step a 91% yield of N-trimethylsilylpyroglutamic acid nitrile whose acylation gives N-acyl compounds 2b,c .