Quantitative determination of dimethylaminoethanol in cosmetic formulations by nuclear magnetic resonance spectroscopy.

A nuclear magnetic resonance (NMR) spectroscopic method was validated for the quantitative determination of dimethylaminoethanol (DMAE) in cosmetic formulations. The linearity in the range from 0.5000 to 1.5000 g (DMAE salt/mass maleic acid) presents a correlation coefficient > 0.99 for all DMAE salts. The repeatability (intraday), expressed as relative standard deviation, ranged from 1.08 to 1.44% for samples and 1.31 to 1.88% for raw materials. The detection limit and quantitation limit were 0.0017 and 0.0051 g for DMAE, 0.0018 and 0.0054 g for DMAE bitartrate, and 0.0023 and 0.0071 g for DMAE acetamidobenzoate, respectively. The proposed method is simple, precise, and accurate and can be used in the quality control of raw materials and cosmetic gels containing these compounds as active substances.

Impact of ferulic acid and resveratrol on the effectiveness and safety of sunscreen

Abstract The combination of avobenzone (AVO) and octyl ρ-methoxycinnamate (OMC) is widely used to ensure broad-spectrum photo-protection because they absorb UVA and UVB, respectively. However, they are thermally and photo unstable because they degrade and undergo photo- tautomerization and trans-cis isomerization, thus reducing their photo-protection efficacy during UV exposure. This study aimed to evaluate the potential use of the antioxidants ferulic acid and resveratrol as stabilizing substances in AVO and OMC mixtures in solution or emulsion. The effects of both antioxidants on the thermal/photo-stability and suppression of the filter singlet state, besides skin permeation, were evaluated. Both antioxidants contributed to preserving OMC and AVO during the thermal stability test, which relates to the maintenance of photo-protection even after storing the formulations at high temperatures. Nevertheless, although resveratrol retained part of the OMC trans isomer and suppressed the AVO singlet state when exposed to UV, no contribution to photo-protection stability was observed, contrary to expectations. Regarding the permeation assay, the addition of both antioxidants was accompanied by a reduction of AVO permeation, while resveratrol increased OMC permeation. Thus, the chemical and physicochemical properties of these antioxidants impacted their efficacy and safety profiles; therefore, further studies are required to establish the real cost-benefit ratio for their use in sunscreens.

Derivados azoicos da oxina com sulfas potencialmente antimalaricas / Oxine azoic derivatives with potentially antimalarial sulfonamides

Com o objetivo de obter farmacos potencialmente antimalaricos prepararam-se, pelo processo de hibridacao molecular, cinco compostos mediante reacao do sal de diazonio e sulfas antimalaricas - sulfadiazina, sulfadoxina, sulfametoxipiridazina, sulfametoxazol e sulfamonometoxina - com a oxina (8-hidroxiquinolina). Submetidos a analises espectrometricas - IV, UV, RMP -, os derivados apresentaram caracteristicas das estruturas propostas

Tiossemicarbazonas heterocíclicas potencialmente antimaláricas: I. Aspectos estruturais / Potentially antimalarial heterocyclic thiosemicarbazones: I. Structural aspects

Com o objetivo de elucidar a estrutura de tiossemicarbazonas de aldeídos heterocíclicos, potencialmente antimaláricos, foram preparados quatro compostos desta classe, sendo analisados mediante espectrometria de infravermelho e de ressonância magnética protônica. A análise estrutural sugere grande conjugaçäo por deslocalizaçäo eletrônica, estabilizando a cadeia lateral em determinada configuraçäo, onde um dos prótons tioureídicos interage com o grupo carbonila e o outro com o átomo de nitrogênio da dupla ligaçäo