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Abstract(s)
Pterospartum tridentatum (L.) Willk., Gomphrena globosa L. and Cymbopogon citratus (DC) Stapf. são plantas medicinais que requerem uma caracterização química mais detalhada, devido à importância do seu consumo em infusões. Assim, o perfil individual em tocoferóis, açúcares livres e ácidos orgânicos foi efetuado por cromatografia líquida de alta eficiência (HPLC) acoplada a diferentes detetores (florescência, índice de refração e detetor de díodos, respetivamente). A composição fenólica (e.g., ácidos fenólicos e flavonoides) foi também analisada por técnicas de cromatografia e espetrometria de massa. A atividade antioxidante dos extratos metanólicos e das infusões foi avaliada através da atividade captadora de radicais livres, poder redutor, inibição da descoloração do β-caroteno e inibição da peroxidação lipídica em homogeneizados cerebrais.
Nos últimos anos, têm surgido estudos de avaliação dos efeitos sinergistas resultantes da combinação de plantas, destacando o maior potencial das misturas quando comparados com as plantas individuais. As três espécies mencionadas anteriormente são exemplos de plantas medicinais com propriedades antioxidantes próprias, mas que podem mostrar melhorias quando combinadas. Assim, avaliou-se também a atividade antioxidante das infusões preparadas a partir das plantas individuais e de misturas dessas plantas em diferentes proporções.
C. citratus revelou o maior teor em α-tocoferol, tocoferóis totais, glucose sacarose, ácidos succínico e ascórbico, tendo ainda apresentado a mais elevada capacidade de inibição da descoloração do β-caroteno e peroxidação lipídica; a luteolina 2''-O-ramnosil-6-C-glucósido foi o composto maioritário no extrato metanólico dessa planta. P. tridentatum apresentou a maior concentração de frutose e açúcares totais, revelando também a maior atividade captadora de radicais livres e poder redutor; derivados de di-hidroflavonol e isoflavona foram os compostos mais significativos no extrato metanólico. Finalmente, G. globosa demonstrou a maior concentração em ácidos orgânicos, sendo o canferol 3-O-rutinósido o composto fenólico mais abundante no extrato metanólico; foram ainda identificadas betacianidinas nesta amostra.
O perfil fenólico foi muito similar nos extratos metanólicos e nas infusões. Para as infusões, a ordem de eficácia antioxidante foi a seguinte P. tridentatum> C. citratus> G. globosa, o que pode estar relacionado com a diferente composição em compostos fenólicos, principalmente flavonoides. Quando se combinaram as plantas em estudo, observaram-se maioritariamente efeitos sinergistas na atividade antioxidante das infusões; os efeitos foram mais significativos nas proporções de 40%:60% (tanto de P. tridentatum e C. citratus, como G. globosa e C. citratus). A infusão obtida a partir de 40% de P. tridentatum e 60% de C. citratus foi a que apresentou propriedades antioxidantes mais elevadas, devido ao aumento da percentagem individual da planta com maior atividade antioxidante, comparativamente à mistura de 25%:75%.
Tanto quanto sabemos, este é o primeiro trabalho que descreve a composição química de G. globosa e C. citratus. Dada a importância do consumo das três plantas mencionadas, o estudo da sua composição fitoquímica e das suas propriedades antioxidantes é de particular interesse. O presente trabalho valida ainda a comercialização das espécies combinadas em proporções específicas.
Pterospartum tridentatum (L.) Willk., Gomphrena globosa L. and Cymbopogon citratus (DC) Stapf. are medicinal plants that require a more detailed chemical characterization, given the importance of their consumption as infusions. Therefore, the individual profiles in tocopherols, free sugars and organic acids were obtained by high performance liquid chromatography (HPLC) coupled to different detectors (fluorescence, refraction index and photodiode array, respectively). Phenolic composition (e.g., phenolic acids and flavonoids) was also analysed by chromatographic and mass spectrometry techniques, and the antioxidant activity was also accessed through free radicals scavenging activity, reducing power and inhibition of lipid peroxidation in brain homogenates, for methanol extracts as for infusions. In recent years, studies focused on the evaluation of synergistic effects of combined plants are emerging and seem to highlight the potential of the mixtures when compared with the individual plants. These three plants are examples of medicinal plants with antioxidant properties by their own, but that can be improved when mixed. In the present work, the antioxidant activity and phenolic compounds were determined in the infusions prepared from the individual plants, as mentioned above, and from mixtures of these plants in different proportions. C. citratus revealed the highest content of α-tocopherol, total tocopherols, glucose, sucrose, succinic and ascorbic acids, with the highest -carotene bleaching and lipid peroxidation inhibitions; luteolin 2´´-O-rhamnosyl-6-C-glucoside was the main compound in its methanolic extract. P. tridentatum presented the highest fructose and total sugars content, revealing the highest free radicals scavenging activity and reducing power; dihydroflavonol and isoflavone derivatives were mainly detected in the methanolic extract. Finnaly, G. globosa showed the highest organic acids concentration, being kaempferol 3-O-rutinoside the most abundant phenolic compound in the methanoli extract; betacyanins were also identified in this sample. The phenolic profile was very similar in the methanolic extracts and infusions. Regarding infusions, P. tridentatum > C. citratus > G. globosa was the order observed for antioxidant efficacy, which can be related to their different composition in phenolic compounds namely, flavonoids. Synergism was the main effect observed among the tested mixtures, mainly for the infusions prepared from the plants in proportion 40%:60% (either P. tridentatum and C. citratus; or G. globosa and C. citratus). The infusion obtained with 40% of P. tridentatum and 60% of C. citratus gave the highest antioxidant properties, due to the increasing percentage of the individual plant with the highest antioxidant activity, in comparison with the mixture 25%:75%. As far as we know, this is the first study reporting chemical composition of G. globosa and C. citratus. It is very interesting to study the phytochemical composition of these plants, and their properties given the importance of their consumption. The present study also validates the commercialization of the studied species combined in specific proportions.
Pterospartum tridentatum (L.) Willk., Gomphrena globosa L. and Cymbopogon citratus (DC) Stapf. are medicinal plants that require a more detailed chemical characterization, given the importance of their consumption as infusions. Therefore, the individual profiles in tocopherols, free sugars and organic acids were obtained by high performance liquid chromatography (HPLC) coupled to different detectors (fluorescence, refraction index and photodiode array, respectively). Phenolic composition (e.g., phenolic acids and flavonoids) was also analysed by chromatographic and mass spectrometry techniques, and the antioxidant activity was also accessed through free radicals scavenging activity, reducing power and inhibition of lipid peroxidation in brain homogenates, for methanol extracts as for infusions. In recent years, studies focused on the evaluation of synergistic effects of combined plants are emerging and seem to highlight the potential of the mixtures when compared with the individual plants. These three plants are examples of medicinal plants with antioxidant properties by their own, but that can be improved when mixed. In the present work, the antioxidant activity and phenolic compounds were determined in the infusions prepared from the individual plants, as mentioned above, and from mixtures of these plants in different proportions. C. citratus revealed the highest content of α-tocopherol, total tocopherols, glucose, sucrose, succinic and ascorbic acids, with the highest -carotene bleaching and lipid peroxidation inhibitions; luteolin 2´´-O-rhamnosyl-6-C-glucoside was the main compound in its methanolic extract. P. tridentatum presented the highest fructose and total sugars content, revealing the highest free radicals scavenging activity and reducing power; dihydroflavonol and isoflavone derivatives were mainly detected in the methanolic extract. Finnaly, G. globosa showed the highest organic acids concentration, being kaempferol 3-O-rutinoside the most abundant phenolic compound in the methanoli extract; betacyanins were also identified in this sample. The phenolic profile was very similar in the methanolic extracts and infusions. Regarding infusions, P. tridentatum > C. citratus > G. globosa was the order observed for antioxidant efficacy, which can be related to their different composition in phenolic compounds namely, flavonoids. Synergism was the main effect observed among the tested mixtures, mainly for the infusions prepared from the plants in proportion 40%:60% (either P. tridentatum and C. citratus; or G. globosa and C. citratus). The infusion obtained with 40% of P. tridentatum and 60% of C. citratus gave the highest antioxidant properties, due to the increasing percentage of the individual plant with the highest antioxidant activity, in comparison with the mixture 25%:75%. As far as we know, this is the first study reporting chemical composition of G. globosa and C. citratus. It is very interesting to study the phytochemical composition of these plants, and their properties given the importance of their consumption. The present study also validates the commercialization of the studied species combined in specific proportions.
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Mestrado de dupla diplomação com a Universidad de Salamanca