Determinação do ácido Rosmarínico em Salvia Officinalis L., Lamiaceae, e avaliação de sua toxicidade e influência na Melanogênese

Orientador : Prof. Dr. Brás Heleno de OliveiraDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências da Saúde, Programa de Pós-Graduação em Ciências Farmacêuticas. Defesa: Curitiba, 01/03/2010Bibliografia: fls. 122-134Área de concentração: Insumos, medicamentos e correlatosResumo: O acido rosmarinico e um ester dos acidos cafeico e 3,4-di-hidroxifenillatico, encontrado em diversas especies vegetais, tais como a Salvia officinalis L. (salvia) e o Rosmarinus officinalis (alecrim). Apresenta diversas atividades biologicas, tais como antiseptica, antioxidante, antiinflamatoria, antiviral, hipoglicemiante, antitumoral e neuroprotetora. Prevendo o possivel uso do acido rosmarinico como farmaco e considerando seu amplo uso pela populacao atraves da salvia, tanto a substancia como a especie devem ser objeto de estudo na area analitica e com relacao as suas atividades biologicas. O presente trabalhoteve por objetivo isolar o acido rosmarinico da salvia, otimizar e validar um metodo de extracao e determinacao deste analito na materia-prima vegetal, e avaliar a toxicidade e a influencia do acido rosmarinico e de extratos de salvia na melanogenese. Para o isolamento do acido rosmarinico usou-se um extrato comercial de salvia que foi submetido a fracionamento cromatografico. O acido rosmarinico isolado foi identificado por RMN de 1H e 13C e por espectrometria UV-VIS. Em seguida, realizou-se a otimizacao das melhores condicoes para extracao do acido rosmarinico de salvia atraves de planejamento fatorial de experimentos, partindo-se de 100 mg de material vegetal com tamanho de particula entre 310 e 740 ƒÊm. Diluicao da droga em 10 mL de metanol 40%, contendo 1 mg/mL de acido ascorbico e 10 mM de EDTA, sonicacao por 20 minutos a 45 ‹C, com posterior filtracao e diluicao para injecao em cromatografo, foram as melhores condicoes estabelecidas para a extracao do analito. Todas as amostras foram analisadas por CLAE em coluna C18, eluidas com metanol:agua (acidificada) nas proporcoes 45:55 (v/v) ate 5 min. e 80:20 (v/v) de 5 a 10 min. de corrida, com fluxo de 1 mL/min. e deteccao em 330 nm. O metodo foi posteriormente submetido a validacao, com analise dos aspectos especificidade, seletividade, linearidade, faixa de aplicacao, precisao repetibilidade e intermediaria e exatidao. Todos os testes obtiveram resultados dentro do especificado pela legislacao, possibilitando o uso do metodo para o fim desejado. A avaliacao das atividades biologicas foi feita com o acido rosmarinico isolado, com um extrato fluido 1:1 e com uma infusao 1:10 de salvia. Todos foram avaliados com relacao a toxicidade a nauplios da A. salina. Nenhum deles apresentou toxicidade significativa (CL50 > 1000 ƒÊg/mL). As mesmas amostras foram tambem testadas com relacao a toxicidade as linhagens celulares McCoy e B16F10. A linhagem McCoy foi mais sensivel aos tratamentos principalmente nas maiores concentracoes. A linhagem celular de melanoma murino B16F10 apresentou maior resistencia aos tratamentos, e as concentracoes dos testes que nao apresentaram toxicidade a essa linhagem foram avaliadas quanto a influencia na melanogenese. Para tal, culturas de celulas B16F10, tratadas por 24 horas com as diferentes concentracoes de acido rosmarinico e de extratos de salvia, tiveram a concentracao de melanina e de atividade de tirosinase celular determinadas. Lisados de celulas nao tratadas previamente foram incubados por 60 min. a 37 ‹C, na presenca de L-DOPA e dos testes para determinacao da atividade de tirosinase invitro. A partir dos experimentos foi possivel verificar que o acido rosmarinico apresenta dupla acao melanogenica, sendo capaz de aumentar a sintese de melanina e de tirosinase em concentracoes mais baixas (10 ƒÊM) e de inibi-la em concentracoes mais altas (1000 ƒÊM). Esta substancia foi uma das responsaveis pela inducao da sintese de melanina pelo extrato fluido e pela infusao de salvia na concentracao de 10 ƒÊM de acido rosmarinico. Mas os extratos nao influenciaram a atividade de tirosinase da mesma forma que o acido rosmarinico, em consequencia das acoes de outras substancias presentes nos mesmos. A partir deste trabalho desenvolveram-se metodologias de extracao e determinacao que podem facilitar o estudo do acido rosmarinico e da salvia nas mais diversas areas da pesquisa cientifica e, ainda, ampliou-se o conhecimento das atividades biologicas do acido rosmarinico e da salvia, abrindo espaco para estudos mais aprofundados de ambos na pesquisa e desenvolvimento de novos farmacos e/ou fitoterapicos para tratamento de patologias pigmentares.Abstract: Rosmarinic acid is an ester of caffeic and 3,4-dihydroxyphenyllactic acids, found in many species, such as Salvia officinalis L. (sage) and Rosmarinus officinalis (rosemary). He has several biological activities, such as antiseptic, antioxidant, anti-inflammatory, antiviral, hypoglycemic, antitumor and neuroprotective. Predicting the possible use of rosmarinic acid as a therapeutical drug and considering its idespread use by the population through the sage, both the substance and the species should be studied in the analytical and in relation to their biological activities. This study aimed to isolate the rosmarinic acid from sage, to optimize and validate a method of extraction and determination of this analyte in plant material and to evaluate the toxicity and the influence of rosmarinic acid and sage on melanogenesis. For the isolation of rosmarinic acid a commercial extract of sage was submitted to chromatographic separation. Isolated rosmarinic acid was identified by 1H NMR and 13C and UV-VIS spectrometry. After this, the optimization of the best conditions for the extraction of rosmarinic acid from sage by factorial design of experiments was carried out, starting from 100 mg of plant material with particle size between 310 and 740 micrometers. Dilution of the drug in 10 mL of methanol 40% containing 1 mg/mL ascorbic acid and 10 mM EDTA, sonication for 20 minutes at 45 ° C with subsequent filtration and dilution to injection in chromatographic system were the best conditions established for extraction of the analyte. All samples were analyzed by HPLC on C18 column, eluted with methanol: water (acidified) at 45:55 (v / v) until 5 min. and at 80:20 (v / v) from 5 to 10 min., flow rate of 1 mL / min. and detection at 330 nm. The method was subsequently subjected to validation, from the analysis of specificity, selectivity, linearity, range of application, repeatability, intermediate precision and accuracy parameters. All the values obtained for the analyzed parameters were in accordance with the established by national and international rules, allowing the use of the method for the intended purpose. Evaluation of biological activities was carried out with rosmarinic acid, a fluid extract and an infusion of sage. All were evaluated for toxicity to A. salina nauplii, and the results showed that none of them presented significant toxicity (LC50> 1000 mg / mL). Both rosmarinic acid and sage extracts were also tested for toxicity to B16F10 and McCoy cell lines. McCoy cell cultures were more sensitive, especially at higher concentrations of the treatments. The murine melanoma B16F10 cell line was more resistant to treatment, and concentrations of tests that showed no toxicity to this strain were evaluated for their influence on melanogenesis. B16F10 cells treated for 24 hours with different concentrations of rosmarinic acid and extracts of sage had the concentration of melanin and tyrosinase activity determined. Non-pretreated cell lysates were incubated for 60 min. at 37 °C in the presence of L-DOPA and tests to determine the activity of tyrosinase in vitro. From the experiments we observed that rosmarinic acid has dual effect on melanogenic, being able to increase melanin synthesis and tyrosinase at lower concentrations (10 ìM) and inhibit it at higher concentrations (1000 ìM). This substance was the mainly responsible for the induction of melanin synthesis by fluid extract and infusion of sage in a concentration of 10 ìM. But the extracts did not influence the activity of tyrosinase in the same way that rosmarinic acid, as a result of the actions of other present substances. From this work analytical methods to extract and determine rosmarinic acid were developed, which can facilitate the study of this substance and sage in several areas of scientific research. The knowledge of the biological activities of rosmarinic acid and sage was also expanded, collaborating with future studies of both on the research and development of new drugs and/or herbal medicines for the treatment of pigmentary disorders

Site-specific glycan analysis of proteins in cell culture conditioned media and subcellular fractions by LC-MS/MS for understanding the impact of process conditions on N-glycosylation

Protein glycosylation, which involves the attachment of sugar residues to proteins, is an important post-translational modification that can influence the structure, pharmacological activity and stability of therapeutic proteins. The mechanisms by which cells modify and process these sugars therefore needs to be well understood and tightly controlled during protein production to ensure consistent product quality. Typically, glycosylation patterns are determined for the secreted therapeutic protein found in the conditioned media (CM). However, since glycosylation occurs through enzymatic reactions within the cellular endomembrane system, the glycosylation profile of the therapeutic protein in different intracellular compartments can also provide valuable insight into the static and dynamic properties of the cell culture system that impact protein glycosylation. This study focuses on determination of glycosylation patterns in CM and different sub-cellular fractions for three distinct N-glycosylation sites of a therapeutic Fc-fusion protein, by applying the Selected Reaction Monitoring (SRM) approach coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). SRM is a rapidly evolving technique for the reliable quantification of low abundance glycopeptides, since it reduces noise and enhances signal intensity by monitoring a select number of predetermined transitions. This mode of analysis was successfully applied for comprehensive site-specific glycan profiling of the therapeutic protein from CM and sub-cellular fractions during CHO cell culture, providing an overview of intermediate and final glycan species formed during the glycosylation process. The distinct glycan distribution patterns for the Fc-fusion protein in CM and different sub-cellular fractions, revealed through this effort, provide a window for understanding the impact of cell culture conditions on the glycosylation pathway, and possibly identify the bottlenecks in generation of glycan species of interest

Longitudinal cohort study investigating neurodevelopmental and socioemotional outcomes in school-entry aged children after open heart surgery in Australia and New Zealand: the NITRIC follow-up study protocol

Introduction: Despite growing awareness of neurodevelopmental impairments in children with congenital heart disease (CHD), there is a lack of large, longitudinal, population-based cohorts. Little is known about the contemporary neurodevelopmental profile and the emergence of specific impairments in children with CHD entering school. The performance of standardised screening tools to predict neurodevelopmental outcomes at school age in this high-risk population remains poorly understood. The NITric oxide during cardiopulmonary bypass to improve Recovery in Infants with Congenital heart defects (NITRIC) trial randomised 1371 children <2 years of age, investigating the effect of gaseous nitric oxide applied into the cardiopulmonary bypass oxygenator during heart surgery. The NITRIC follow-up study will follow this cohort annually until 5 years of age to assess outcomes related to cognition and socioemotional behaviour at school entry, identify risk factors for adverse outcomes and evaluate the performance of screening tools. Methods and analysis: Approximately 1150 children from the NITRIC trial across five sites in Australia and New Zealand will be eligible. Follow-up assessments will occur in two stages: (1) annual online screening of global neurodevelopment, socioemotional and executive functioning, health-related quality of life and parenting stress at ages 2–5 years; and (2) face-to-face assessment at age 5 years assessing intellectual ability, attention, memory and processing speed; fine motor skills; language and communication; and socioemotional outcomes. Cognitive and socioemotional outcomes and trajectories of neurodevelopment will be described and demographic, clinical, genetic and environmental predictors of these outcomes will be explored. Ethics and dissemination: Ethical approval has been obtained from the Children’s Health Queensland (HREC/20/QCHQ/70626) and New Zealand Health and Disability (21/NTA/83) Research Ethics Committees. The findings will inform the development of clinical decision tools and improve preventative and intervention strategies in children with CHD. Dissemination of the outcomes of the study is expected via publications in peer-reviewed journals, presentation at conferences, via social media, podcast presentations and medical education resources, and through CHD family partners.Trial registration numberThe trial was prospectively registered with the Australian New Zealand Clinical Trials Registry as ‘Gene Expression to Predict Long-Term Neurodevelopmental Outcome in Infants from the NITric oxide during cardiopulmonary bypass to improve Recovery in Infants with Congenital heart defects (NITRIC) Study – A Multicentre Prospective Trial’. Trial registration: ACTRN12621000904875

Different source of commercial vegetable oils may regulate metabolic, inflammatory and redox status in healthy rats.

Our goal was to carry out a comparative study to evaluate the metabolic and inflammatory effects and the redox status of commercial vegetable oils supplementation [linseed (LO), coconut (VCO), and sunflower (SO)] in metabolically healthy rats. The results found in this study showed that the LO group decreased the HOMA-IR and hepatic cholesterol, and increased the serum levels of IL-6. Supplementation with VCO increased glucose and HOMA-IR, cholesterol concentration and serum triacylglycerol (TAG). In this group, there was also an increase in TBARS. In the SO group there was a decrease in serum concentrations of cholesterol and TAG and an increase in hepatic concentration of these lipids. In addition, in the SO group there was a decrease in hepatic and s?rum concentrations of IL-6 and hepatic levels of TNF, as well as a decrease in the GSH/GSSG ratio, suggesting changes in glutathione metabolism and inflammatory mediators

Using Polarized Spectroscopy to Investigate Order in Thin-Films of Ionic Self-Assembled Materials Based on Azo-Dyes

Three series of ionic self-assembled materials based on anionic azo-dyes and cationic benzalkonium surfactants were synthesized and thin films were prepared by spin-casting. These thin films appear isotropic when investigated with polarized optical microscopy, although they are highly anisotropic. Here, three series of homologous materials were studied to rationalize this observation. Investigating thin films of ordered molecular materials relies to a large extent on advanced experimental methods and large research infrastructure. A statement that in particular is true for thin films with nanoscopic order, where X-ray reflectometry, X-ray and neutron scattering, electron microscopy and atom force microscopy (AFM) has to be used to elucidate film morphology and the underlying molecular structure. Here, the thin films were investigated using AFM, optical microscopy and polarized absorption spectroscopy. It was shown that by using numerical method for treating the polarized absorption spectroscopy data, the molecular structure can be elucidated. Further, it was shown that polarized optical spectroscopy is a general tool that allows determination of the molecular order in thin films. Finally, it was found that full control of thermal history and rigorous control of the ionic self-assembly conditions are required to reproducibly make these materials of high nanoscopic order. Similarly, the conditions for spin-casting are shown to be determining for the overall thin film morphology, while molecular order is maintained

Livres offerts

Livres offerts. In: Comptes rendus des séances de l'Académie des Inscriptions et Belles-Lettres, 58ᵉ année, N. 3, 1914. pp. 270-271

Determinação do ácido Rosmarínico em Salvia Officinalis L., Lamiaceae, e avaliação de sua toxicidade e influência na Melanogênese

Orientador : Prof. Dr. Brás Heleno de OliveiraDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências da Saúde, Programa de Pós-Graduação em Ciências Farmacêuticas. Defesa: Curitiba, 01/03/2010Bibliografia: fls. 122-134Área de concentração: Insumos, medicamentos e correlatosResumo: O acido rosmarinico e um ester dos acidos cafeico e 3,4-di-hidroxifenillatico, encontrado em diversas especies vegetais, tais como a Salvia officinalis L. (salvia) e o Rosmarinus officinalis (alecrim). Apresenta diversas atividades biologicas, tais como antiseptica, antioxidante, antiinflamatoria, antiviral, hipoglicemiante, antitumoral e neuroprotetora. Prevendo o possivel uso do acido rosmarinico como farmaco e considerando seu amplo uso pela populacao atraves da salvia, tanto a substancia como a especie devem ser objeto de estudo na area analitica e com relacao as suas atividades biologicas. O presente trabalhoteve por objetivo isolar o acido rosmarinico da salvia, otimizar e validar um metodo de extracao e determinacao deste analito na materia-prima vegetal, e avaliar a toxicidade e a influencia do acido rosmarinico e de extratos de salvia na melanogenese. Para o isolamento do acido rosmarinico usou-se um extrato comercial de salvia que foi submetido a fracionamento cromatografico. O acido rosmarinico isolado foi identificado por RMN de 1H e 13C e por espectrometria UV-VIS. Em seguida, realizou-se a otimizacao das melhores condicoes para extracao do acido rosmarinico de salvia atraves de planejamento fatorial de experimentos, partindo-se de 100 mg de material vegetal com tamanho de particula entre 310 e 740 ƒÊm. Diluicao da droga em 10 mL de metanol 40%, contendo 1 mg/mL de acido ascorbico e 10 mM de EDTA, sonicacao por 20 minutos a 45 ‹C, com posterior filtracao e diluicao para injecao em cromatografo, foram as melhores condicoes estabelecidas para a extracao do analito. Todas as amostras foram analisadas por CLAE em coluna C18, eluidas com metanol:agua (acidificada) nas proporcoes 45:55 (v/v) ate 5 min. e 80:20 (v/v) de 5 a 10 min. de corrida, com fluxo de 1 mL/min. e deteccao em 330 nm. O metodo foi posteriormente submetido a validacao, com analise dos aspectos especificidade, seletividade, linearidade, faixa de aplicacao, precisao repetibilidade e intermediaria e exatidao. Todos os testes obtiveram resultados dentro do especificado pela legislacao, possibilitando o uso do metodo para o fim desejado. A avaliacao das atividades biologicas foi feita com o acido rosmarinico isolado, com um extrato fluido 1:1 e com uma infusao 1:10 de salvia. Todos foram avaliados com relacao a toxicidade a nauplios da A. salina. Nenhum deles apresentou toxicidade significativa (CL50 > 1000 ƒÊg/mL). As mesmas amostras foram tambem testadas com relacao a toxicidade as linhagens celulares McCoy e B16F10. A linhagem McCoy foi mais sensivel aos tratamentos principalmente nas maiores concentracoes. A linhagem celular de melanoma murino B16F10 apresentou maior resistencia aos tratamentos, e as concentracoes dos testes que nao apresentaram toxicidade a essa linhagem foram avaliadas quanto a influencia na melanogenese. Para tal, culturas de celulas B16F10, tratadas por 24 horas com as diferentes concentracoes de acido rosmarinico e de extratos de salvia, tiveram a concentracao de melanina e de atividade de tirosinase celular determinadas. Lisados de celulas nao tratadas previamente foram incubados por 60 min. a 37 ‹C, na presenca de L-DOPA e dos testes para determinacao da atividade de tirosinase invitro. A partir dos experimentos foi possivel verificar que o acido rosmarinico apresenta dupla acao melanogenica, sendo capaz de aumentar a sintese de melanina e de tirosinase em concentracoes mais baixas (10 ƒÊM) e de inibi-la em concentracoes mais altas (1000 ƒÊM). Esta substancia foi uma das responsaveis pela inducao da sintese de melanina pelo extrato fluido e pela infusao de salvia na concentracao de 10 ƒÊM de acido rosmarinico. Mas os extratos nao influenciaram a atividade de tirosinase da mesma forma que o acido rosmarinico, em consequencia das acoes de outras substancias presentes nos mesmos. A partir deste trabalho desenvolveram-se metodologias de extracao e determinacao que podem facilitar o estudo do acido rosmarinico e da salvia nas mais diversas areas da pesquisa cientifica e, ainda, ampliou-se o conhecimento das atividades biologicas do acido rosmarinico e da salvia, abrindo espaco para estudos mais aprofundados de ambos na pesquisa e desenvolvimento de novos farmacos e/ou fitoterapicos para tratamento de patologias pigmentares.Abstract: Rosmarinic acid is an ester of caffeic and 3,4-dihydroxyphenyllactic acids, found in many species, such as Salvia officinalis L. (sage) and Rosmarinus officinalis (rosemary). He has several biological activities, such as antiseptic, antioxidant, anti-inflammatory, antiviral, hypoglycemic, antitumor and neuroprotective. Predicting the possible use of rosmarinic acid as a therapeutical drug and considering its idespread use by the population through the sage, both the substance and the species should be studied in the analytical and in relation to their biological activities. This study aimed to isolate the rosmarinic acid from sage, to optimize and validate a method of extraction and determination of this analyte in plant material and to evaluate the toxicity and the influence of rosmarinic acid and sage on melanogenesis. For the isolation of rosmarinic acid a commercial extract of sage was submitted to chromatographic separation. Isolated rosmarinic acid was identified by 1H NMR and 13C and UV-VIS spectrometry. After this, the optimization of the best conditions for the extraction of rosmarinic acid from sage by factorial design of experiments was carried out, starting from 100 mg of plant material with particle size between 310 and 740 micrometers. Dilution of the drug in 10 mL of methanol 40% containing 1 mg/mL ascorbic acid and 10 mM EDTA, sonication for 20 minutes at 45 ° C with subsequent filtration and dilution to injection in chromatographic system were the best conditions established for extraction of the analyte. All samples were analyzed by HPLC on C18 column, eluted with methanol: water (acidified) at 45:55 (v / v) until 5 min. and at 80:20 (v / v) from 5 to 10 min., flow rate of 1 mL / min. and detection at 330 nm. The method was subsequently subjected to validation, from the analysis of specificity, selectivity, linearity, range of application, repeatability, intermediate precision and accuracy parameters. All the values obtained for the analyzed parameters were in accordance with the established by national and international rules, allowing the use of the method for the intended purpose. Evaluation of biological activities was carried out with rosmarinic acid, a fluid extract and an infusion of sage. All were evaluated for toxicity to A. salina nauplii, and the results showed that none of them presented significant toxicity (LC50> 1000 mg / mL). Both rosmarinic acid and sage extracts were also tested for toxicity to B16F10 and McCoy cell lines. McCoy cell cultures were more sensitive, especially at higher concentrations of the treatments. The murine melanoma B16F10 cell line was more resistant to treatment, and concentrations of tests that showed no toxicity to this strain were evaluated for their influence on melanogenesis. B16F10 cells treated for 24 hours with different concentrations of rosmarinic acid and extracts of sage had the concentration of melanin and tyrosinase activity determined. Non-pretreated cell lysates were incubated for 60 min. at 37 °C in the presence of L-DOPA and tests to determine the activity of tyrosinase in vitro. From the experiments we observed that rosmarinic acid has dual effect on melanogenic, being able to increase melanin synthesis and tyrosinase at lower concentrations (10 ìM) and inhibit it at higher concentrations (1000 ìM). This substance was the mainly responsible for the induction of melanin synthesis by fluid extract and infusion of sage in a concentration of 10 ìM. But the extracts did not influence the activity of tyrosinase in the same way that rosmarinic acid, as a result of the actions of other present substances. From this work analytical methods to extract and determine rosmarinic acid were developed, which can facilitate the study of this substance and sage in several areas of scientific research. The knowledge of the biological activities of rosmarinic acid and sage was also expanded, collaborating with future studies of both on the research and development of new drugs and/or herbal medicines for the treatment of pigmentary disorders

DETERMINAÇÃO DA CONCENTRAÇÃO DE POLIFENÓIS E DO POTENCIAL

Dicksonia sellowiana, a tipical plant from Atlantic Forest, is popularly known by xaxim or samambaiacu. The xaxim is used to make supports for ornamental plants; as well as is used against scabies, itch in the body and solitaria by the indians, and popularly is used as fibre source. Studies have shown medical value in the breath system. Knowing the increasing search for phytoterapics with antioxidant action against free radicals, the objective of this study was to evaluate the potencial antioxidant of the hexane, the diclorometane and the ethyl acetate fractions, as well as of the total extract of Dicksonia sellowiana leaves, and to verify the phenolic compounds concentration of these fractions. The Folin-Ciocalteau method was used to determine the phenolic acids doses, using acid galic as a phenolic compound standard. The antioxidant activity was determined by the phosphomolybdenum complex reduction, using vitamin C and rutin as antioxidants standards. The increasing values of phenolic acids concentration and of antioxidant activity are: hexane fraction, total extract, diclorometane fraction and ethyl acetate fraction. These results showed that the phenolic compounds of xaxim had significant contribution to the antioxidant activity, and, regarding that these compounds have the higher concentration in the ethyl acetate fraction, this fraction has the more significant antioxidant activity, which can be studied for the action against the free radicals. Key words: Dicksonia sellowiana, phenolic acids, antioxidant activity.A Dicksonia sellowiana, planta típica da Mata Atlântica, é popularmente conhecida como xaxim ou samambaiaçú. O xaxim é utilizado para a fabricação de suportes para plantas ornamentais; também usado contra sarna, coceira no corpo e solitária pelos índios , e popularmente como fonte de fibras. Estudos revelam seu valor medicinal no sistema respiratório. Conhecendo-se a crescente busca por fitoterápicos com antioxidantes que combatem radicais livres, o presente trabalho teve como objetivo analisar o potencial antioxidante das frações hexano, diclorometano e acetato de etila e do extrato total de folhas de Dicksonia sellowiana, e verificar a concentração de polifenóis das mesmas. O doseamento de compostos fenólicos foi realizado pelo método de Folin-Ciocalteau, usando-se ácido gálico como padrão de composto fenólico. A atividade antioxidante foi determinada pelo ensaio de redução do complexo fosfomolibdênio, usando-se vitamina C e rutina como padrões de antioxidantes. A partir dos ensaios pode-se observar que tanto os valores de concentração de compostos fenólicos como os de atividade antioxidante são decrescentes na ordem: fração acetato de etila, fração diclorometano, extrato total e fração hexano. Este resultado demonstra que os polifenóis do xaxim contribuem significativamente para a atividade antioxidante, e, pelo fato destes estarem presentes em maior concentração na fração acetato de etila, esta apresenta o potencial antioxidante mais significativo, o qual pode vir a ser estudado no combate à radicais livres. Palavras-chaves: Dicksonia sellowiana, compostos fenólicos, atividade antioxidante