Alexis Vidal Novoa

Antioxidant activity and possible bioactive components in hydrophilic and lipophilic fractions from the seaweed Halimeda incrassata

Hydrophilic and lipophilic fractions, obtained from the marine algae Halimeda incrassata (J.Ellis) J.V.Lamouroux, Halimedaceae, were studied by using the ²-carotene-linoleate assay system. In case of hydrophilic fractions, the total phenolic compounds were quantified and two of their components were identified as salicylic and ferulic acids. From the lipophilic fraction, fatty acid composition was studied. The highest antioxidant activities values were found on the polar fractions containing phenolic acids. The total phenolics content on the hydrophilic fractions was 255 μg of gallic acid equivalents/g of fresh seaweed. To further characterize H. incrassata chemical composition, the total lipid content was quantified (7.4 mg per gram of dried algae) as well as the saturated and unsaturated fatty acids ratio (1:1.46). In summary, this paper adds more convincing evidences in support of the antioxidant abilities of the lyophilized aqueous extract of Halimeda incrassata and it also relates this bioactivity, for the first time, with particular phenolic components of the extract. Altogether, these results represent another step towards the use of this natural product as drug candidates.

Efeito do extrato aquoso de alecrim (Rosmarinus officinalis L.) sobre o estresse oxidativo em ratos diabéticos

OBJECTIVE: This study assessed the effect of aqueous rosemary extract on the oxidative stress of diabetic rats. METHODS: Aqueous rosemary extract was obtained by the sequential method. Total phenolic content was determined by the Folin Ciocateau method and antioxidant activity in vitro was determined by the following methods: β-carotene/linoleic acid, 2,2 Difenil-1-Picril-hidrazil and oxygen radical absorbance capacity. Male Wistar rats were distributed into 5 groups: control, diabetic, and three groups of diabetic animals treated with aqueous rosemary extract in different concentrations: 25, 50 or 100mg/kg orally for 30 days. Diabetes was induced by streptozotocin and, at the end of the experiment, blood was collected to assess the percentage of glycated hemoglobin; liver and brain tissues were collected for the determination of the antioxidant enzymes: superoxide dismutase, catalase, glutatione peroxidase and glutatione reductase. RESULTS: Aqueous rosemary extract contains high levels of phenolic compounds and significant total antioxidant activity in vitro according to the three methods. Aqueous rosemary extract at a concentration of 50mg/kg decreased the percentage of glycated hemoglobin and increased the activity of glutatiose peroxidase and catalase enzymes in the liver and superoxide dismutase in the brain of diabetic rats. However, no dose-response effect was observed in the other concentrations. CONCLUSION: Aqueous rosemary extract presented significant antioxidant capacity in vitro attributed to its high phenolic compound content. When administered to rats at a concentration of 50mg/kg, it proved to be efficient against the oxidative stress secondary to experimental diabetes.

Comparación de las propiedades antioxidantes y contenido de polifenoles de extractos acuosos de las algas marinas Bryothamnion triquetrum y Halimeda opuntia

Objetivos. Evaluar y comparar las propiedades antioxidantes mediante ensayos in vitro de extractosacuosos de las algas roja Bryothamnion triquetrum y verde Halimeda opuntia y su relacion con el contenidode polifenoles. Material y Metodos. Se utilizaron las tecnicas in vitro: DPPH, Capacidad reductora, Inhibicion de laperoxidacion lipidica e inhibicion de la hemolisis inducida por AAPH .Resultados. B. triquetrum: DPPH; CI50=1,15 ± 0,06, capacidad reductora a concentracion; 128 mg/mL,DO=2,798, inhibicion de la peroxidacion lipidica; CI50=5,09± 0,25 e inhibicion de la hemolisis con 12 mg/mL; 35 %. H. opuntia: DPPH; CI50=12,34 ± 0,30 mg/mL, capacidad reductora; DO=0,800, inhibicion de laperoxidacion lipidica; CI50=1,25± 0,31 mg/mL e inhibicion de la hemolisis; 82%. Conclusiones. Los resultados evidencian que B triquetrum resulto mucho mas eficiente en los ensayos deDPPH y Capacidad reductora mientras H opuntia resulta mas eficiente en Inhibicion de la peroxidacionlipidica e inhibicion de la hemolisis. Se discuten algunos aspectos acerca de sus posibles mecanismos deaccion.