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Authors
Abstract(s)
O presente trabalho teve como objetivo explorar o potencial antioxidante dos compostos fenólicos das sumidades floridas (capítulos e brácteas e os 15 cm terminais dos caules com folhas que suportam as inflorescências) de Helichrysum stoechas (L.) Moench para aplicações cosméticas e envolveu as seguintes etapas: caracterização química, microencapsulação e incorporação num hidratante.
As propriedades antioxidantes do extrato hidroalcoólico e da decocção foram avaliadas por métodos químicos (determinação do poder redutor e da capacidade captadora de radicais 2,2-difenil-1-picril-hidrazilo (DPPH) e bioquímicos (inibição da descoloração do β-caroteno na presença de radicais livres derivados do ácido linoleico e inibição da formação de espécies reativas do ácido tiobarbitúrico (TBARS) em homogeneizados cerebrais). A composição fenólica foi analisada por cromatografia líquida de alta eficiência de fase reversa acoplada a deteção de díodos e espetrometria de massa com ionização por spray de eletrões (HPLC-DAD-ESI/MS).
Foram identificados dezoito compostos fenólicos diferentes, sendo o ácido 3,5-O-dicafeoilquínico e a miricetina 7-O-acetil-hexósido o ácido fenólico e o flavonoide mais abundante, respetivamente. Comparativamente à decocção, o extrato hidroalcoólico apresentou maior atividade antioxidante e conteúdo fenólico, tendo-se optado pela sua forma liofilizada para prosseguir os estudos de microencapsulação. Para a microencapsulação utilizou-se a técnica da dupla emulsão/evaporação de solvente, produzindo-se microesferas de base policaprolactona (PCL) com o respetivo conteúdo (extrato hidroalcoólico de H. stoechas). Estas foram incorporadas com sucesso num creme hidratante.
Os resultados obtidos demonstraram o potencial antioxidante do extrato hidroalcoólico de H. stoechas e a viabilidade da sua microencapsulação, abrindo novas possibilidades de exploração e aplicação destes extratos fenólicos naturais, nomeadamente na indústria de cosméticos.
The present work explores the antioxidant potential of Helichrysum stoechas (L.) Moench phenolic compounds for cosmetic applications involving the following steps: chemical characterization, microencapsulation and incorporation into a moisturizer. The antioxidant properties of hydroalcoholic extract and decoction were evaluated by chemical (determination of reducing power and scavenging activity of 2,2-diphenyl-1-pycrylhydrazyl, DPPH, radicals) and biochemical (inhibition of β-carotene bleaching in the presence of linoleate free radicals and inhibition of reactive substances of thiobarbituric acid, TBARS, in brain homogenates) assays. The phenolic composition was analysed by high performance liquid chromatography in reverse phase coupled to diode array detection and mass spectrometry with electron spray ionization (HPLC-DAD-ESI/MS). Eighteen different phenolic compounds were identified in flowering aerial parts (decoction and hydroalcoholic extract), being 3,5-O-dicaffeoylquinic acids and myricetin7-O-acylhexoside the most abundant phenolic acid and flavonoid, respectively. Comparatively to the decoction form, the hydroalcoholic extract presented both higher antioxidant activity and higher phenolic content, being its lyophilized form chosen to proceed with microencapsulation studies. Therefore, double emulsion/evaporation microencapsulation technique was applied to produce PCL based microspheres containing H. stoechas hydroalcoholic extract, which were then successfully incorporated into a moisturizer. The results obtained demonstrated the antioxidant potential H. stoechas hydroalcoholic extract and the viability of its microencapsulation, thus opening new perspectives for the exploitation of these natural phenolic extracts in applications such as the cosmetic industry.
The present work explores the antioxidant potential of Helichrysum stoechas (L.) Moench phenolic compounds for cosmetic applications involving the following steps: chemical characterization, microencapsulation and incorporation into a moisturizer. The antioxidant properties of hydroalcoholic extract and decoction were evaluated by chemical (determination of reducing power and scavenging activity of 2,2-diphenyl-1-pycrylhydrazyl, DPPH, radicals) and biochemical (inhibition of β-carotene bleaching in the presence of linoleate free radicals and inhibition of reactive substances of thiobarbituric acid, TBARS, in brain homogenates) assays. The phenolic composition was analysed by high performance liquid chromatography in reverse phase coupled to diode array detection and mass spectrometry with electron spray ionization (HPLC-DAD-ESI/MS). Eighteen different phenolic compounds were identified in flowering aerial parts (decoction and hydroalcoholic extract), being 3,5-O-dicaffeoylquinic acids and myricetin7-O-acylhexoside the most abundant phenolic acid and flavonoid, respectively. Comparatively to the decoction form, the hydroalcoholic extract presented both higher antioxidant activity and higher phenolic content, being its lyophilized form chosen to proceed with microencapsulation studies. Therefore, double emulsion/evaporation microencapsulation technique was applied to produce PCL based microspheres containing H. stoechas hydroalcoholic extract, which were then successfully incorporated into a moisturizer. The results obtained demonstrated the antioxidant potential H. stoechas hydroalcoholic extract and the viability of its microencapsulation, thus opening new perspectives for the exploitation of these natural phenolic extracts in applications such as the cosmetic industry.
Description
Mestrado em cooperação com a Universidade de Salamanca