The antioxidant activity of lemongrass leaves extract against fibroblasts oxidative stress / Atividade antioxidante do extrato das folhas de capim-limão contra o estresse oxidativo em fibroblastos

Objective : The purpose of this research is to assess the antioxidant activity of lemongrass leaves extract in terms of lowering ROS generation and its effect on the viability and proliferation of fibroblasts under oxidative stress. Material and Methods: The antioxidant activity was measured using the DPPH method and the ROS assay was carried out by fluorescent H2DCFDA staining. Viability and proliferation assays were performed using the Cell Counting Kit-8 (CCK-8) and was read at 450 nm using microplate reader. The groups were divided into 8, namely fibroblasts without treatment (comparison group), fibroblast induced by H2O2 (negative control), fibroblast with H2O2 then treated with ascorbic acid (positive control), and fibroblast with H2O2 then treated with lemongrass leaves extract at various concentrations (10, 20, 30, 40, and 50 ppm). Results: The results showed that the antioxidant activity of lemongrass leaves extract had an IC value of 64.17 ppm. ROS production were reduced by the LgLE of all concentrations if compared with negative control (p=0.819). LgLE can maintained the fibroblast viability with 10 ppm of LgLE was the most optimum concentration (p<0.05). LgLE can induced the proliferation of fibroblast, with the most effective was at 24 h of observation (p<0.05). Conclusion: Lemongrass leaves extract has a strong antioxidant activity that can reduce oxidative stress and increase the viability and proliferation of fibroblasts with the optimum concentration is at 10 ppm. (AU)

Objetivo: O intuito deste estudo foi determinar a ação antioxidante do extrato das folhas de capim-limão no que se refere a diminuição da produção de espécies reativas do oxigênio (EROS) e o seu efeito na viabilidade e proliferação de fibroblastos submetidos à estresse oxidativo. Material e Métodos: A atividade antioxidante foi medida utilizando o método de DPPH e o ensaio de EROS foi realizado pela coloração fluorescente de H2DCFDA. Os ensaios de proliferação e viabilidade foram realizados utilizando-se o kit de contagem de células CCK-8 em microplacas de leitura à 450nm. Os grupos foram divididos em 8: Fibroblastos sem tratamento (grupo controle), Fibroblastos tratados com H2O2 (controle negativo), Fibroblastos tratados com H2O2 e extrato da folha de capim-limão em concentrações variadas (10, 20, 30, 40 e 50 ppm). Resultados: Os resultados mostraram que a atividade antioxidante do extrato de capim-limão teve uma IC50 (com o numeroal subscrito) com valor de 64.17ppm. A produção de ROS foi reduzida pelo tratamento com o extrato em todas as concentrações testadas quando comparado ao grupo controle negativo (p=0.819). O extrato manteve a viabilidade dos fibroblastos, sendo 10ppm a concentração menos tóxica (p<0.05). LgLE pôde induzir a proliferação de fibroblastos, sendo que a melhor eficiencia foi após 24h de observação (p<0.05). Conclusão: O extrato das folhas de capim-limão apresentam forte atividade antioxidante reduzindo o estresse oxidativo e aumentando a viabilidade e proliferação de fibroblastos, sendo a concentração ótima de 10ppm. (AU)

Chemoselective Aerobic Cross-Dehydrogenative Coupling of Terminal Alkynes with Hydrosilanes by a Nanoporous Gold Catalyst.

Aerobic cross-dehydrogenative coupling between terminal alkynes and hydrosilanes occurred in the presence of nanoporous gold catalyst under O2 atmosphere. A variety of alkynylsilanes were synthesized in good-to-high yields and the catalyst was easily recovered and reused many times. Furthermore, the chemoselective direct silyl protection of terminal acetylenes of alkynols over the hydroxyl groups was achieved with this catalytic system.