Scielo RSS <![CDATA[Brazilian Archives of Biology and Technology]]> vol. 62 num. lang. en <![CDATA[SciELO Logo]]> <![CDATA[In vitro Antiproliferative and inhibition of oxidative DNA damage activities of n-butanol extract of Limonium bonduelli from Algeria]]> Abstract Plants are the main sources of natural antioxidants in the form of phenolic compounds, which help human beings to deal with oxidative stress, caused by free radical damage. For this reason, the present study was carried out to evaluate the antiproliferative, antioxidant and inhibition of oxidative DNA damage activities of n-butanol extract obtained from aerial parts of Limonium bonduelli. The antioxidant potential was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and inhibition of lipid peroxidation assay. Antiproliferative activity was evaluated using xCELLigence RTCA instrument on two tumor cell lines; HT-29 (human colon adenocarcinoma) and HeLa (human cervix carcinoma). DNA damage inhibition was evaluated using photolyzing 46966 plasmid. Also, total phenolic and total flavonoid contents were determined using a spectrophotometric method. Total phenolic (343 ± 0.05 µg/mg) and flavonoid (220.5 ± 0.04 µg/mg) were indicated as gallic acid and quercetin equivalents respectively. The extract exhibited significant IC50 values in lipid peroxidation (IC50= 181.18 ± 0.65 µg/mL) and DPPH radical scavenging assays (IC50= 14.92 ± 0.032 µg/mL). The extract also partially protected 46966 plasmid DNA from free radical-mediated oxidative stress in a DNA damage inhibition assay and showed concentration-dependent antiproliferative effects. n-butanol extract of L. bonduelli is a rich source of natural antioxidants and anticancer agents. <![CDATA[Microscale direct transesterification of microbial biomass with ethanol for screening of microorganisms by its fatty acid content]]> Abstract We present an improved method of direct transesterification suitable for the quantitative analysis of multiple dry samples for its fatty acid content, using a minimal amount of biomass and reactants. The method features an acid-catalyzed direct alcoholysis of microgram samples of dry biomass; the rationale behind the solvent and reagent proportions chosen is discussed. The method was validated using seven microbial strains with diverse lipid content (Saccharomyces cerevisiae, Saccharomyces boulardii, Candida tropicalis, Haematococcus pluvialis, Chlorella vulgaris, Spirulina platensis and Schizochytrium limacinum), and compared with a macroscale direct transesterification method, and with gravimetric analysis of lipids extracted with solvents. The microscale method showed a conversion of 98.06 ± 0.87% of the lipids, using approximately 3 mg of dry biomass, 1mL of 0.2M H2SO4 dissolved in anhydrous ethanol (the acid is the catalyzer and ethanol the reactant)). The mixture was maintained at 70 °C for 20 h with periodic mixing, and then extracted with 2mL n-heptane and analyzed by GC-FID. The lipid content was then calculated considering dilution and sample mass. This method is effective, reliable, and technically attractive for analytical and comparative purposes. <![CDATA[Effects of gamma radiation on the stability and degradation kinetics of phenolic compounds and antioxidant activity during storage of (Oryza sativa L.) black rice flour]]> Abstract The effects of gamma radiation (0, 1, 2 and 3 kGy) were used to evaluate the stability and thermal degradation kinetics of anthocyanins, as well as the stability of total phenolic compounds (TPC) and antioxidant activity at different temperatures (4, 25, 35 and 45 °C) during the storage (0, 30, 60, 90 and 120 days) of black rice flour. This flour can be used as ingredient for gluten-free cereal products with higher nutritional value. For this it is necessary to preserve the anthocyanin content during thermal processing and shelf-life periods. At time 0, the dose of 3 kGy provided all of the most available bioactive compounds, raising their antioxidant potential, except for TPC. During the storage at different temperatures up to 120 days, gradual losses occurred in all the analysed parameters. Regarding the total anthocyanin content and TPC, the sample irradiated with a 1 kGy dose remained most stable. The analysis of kinetic data indicated a first-order reaction for the degradation of anthocyanins. The combination of irradiation with different temperatures may improve the shelf-life of black rice flour.