A novel procedure to measure the antioxidant capacity of Yerba maté extracts

Yerba maté extracts have in vitro antioxidant capacity attributed to the presence of polyphenolic compounds, mainly chlorogenic acids and dicaffeoylquinic acid derivatives. DPPH is one of the most used assays to measure the antioxidant capacity of pure compounds and plant extracts. It is difficult to compare the results between studies because this assay is applied in too many different conditions by the different research groups. Thus, in order to assess the antioxidant capacity of yerba maté extracts, the following procedure is proposed: 100 µL of an aqueous dilution of the extracts is mixed in duplicate with 3.0 mL of a DPPH 'work solution in absolute methanol (100 µM.L-1), with an incubation time of 120 minutes in darkness at 37 ± 1 °C, and then absorbance is read at 517 nm against absolute methanol. The results should be expressed as ascorbic acid equivalents or Trolox equivalents in mass percentage (g% dm, dry matter) in order to facilitate comparisons. The AOC of the ethanolic extracts ranged between 12.8 and 23.1 g TE % dm and from 9.1 to 16.4 g AAE % dm. The AOC determined by the DPPH assay proposed in the present study can be related to the total polyphenolic content determined by the Folin-Ciocalteu assay

Optimization of callus and cell suspension cultures of Barringtonia racemosa (Lecythidaceae family) for lycopene production

Lycopene is present in a range of fresh fruits and vegetables, especially in the leaves of Barringtonia racemosa. The traditional lycopene extraction from the plant is being employed instead of an easy propagation technique like cell culture process from the leaf explants. We intend to assess how lycopene could be extracted via tissue culture under light (illuminance: 8,200 lux under white fluorescent lamps, photoperiod 16 h per day at 25ºC) and dark. Leaf explants of Barringtonia racemosa were cultured on modified Murashige and Skoog (MS), Woody Plant Medium (WPM) and B5 media, supplemented with different concentrations of 2,4-Dichlorophenoxyacetic acid (2,4-D). Optimal conditions for callus induction and maintenance under both dark and light were investigated, and growth and lycopene accumulation were evaluated. Among media with different concentrations of 2,4-D, fast growing, friable callus initiated within three weeks after culturing on WPM basal medium supplemented with 2.0 mg L-1 (weight per volume) of 2,4-D, whereas callus induction in explants cultured on all other media started only after five weeks. Calli were subcultured once every fortnight. Pale yellow and green calli developed under conditions of dark and light respectively were then selected for evaluation of their lycopene contents. An improved reversed phase of high performance liquid chromatography (HPLC) method was used for a selective chemical determination of the lycopene content. Light induced lycopene production; and likewise maximum lycopene level incubated in light was higher than those incubated in darkness. The best growth rates of callus and cell suspension were achieved in WPM and B5 media respectively. The production of lycopene was growth-dependent through analysis of growth and lycopene content of both callus and cell suspension cultures.O licopeno está presente numa série de frutas frescas e hortaliças principalmente na folhas de Barringtonia racemosa. A extração tradicional do licopeno tem sido empregada no lugar da fácil técnica de propagação como o processo de cultura de células de explantes de folhas. É nossa intenção demonstrar como o licopeno pode ser extraído através de cultura de tecido sob luz (iluminação com lâmpadas fluorescentes brancas de 8.200 lux, 16 h por dia a 25º C) e escuro. Explantes de folhas de Barringtonia racemosa foram cultivados em meio modificado de Murashige e Skoog (MS) para plantas lenhosas e meio B5, suplementado com diferentes concentrações de ácido 2,4-Diclorofenoxiacético (2,4-D). Condições ótimas para indução e manutenção de calos sob luz e escuro foram investigadas e avaliados o crescimento e acumulo de licopeno. Entre meios com diferentes concentrações de 2,4 -D, calos friáveis de crescimento rápido tiveram início em três semanas após serem cultivados em meio basal WPM suplementado com 2.0 mg L-1 (peso por volume) de 2,4-D enquanto indução de calos em explantes cultivados em todos os outros meios começaram somente após cinco semanas. Calos foram subrepicados a cada 15 dias. Calos amarelo-pálido e verdes desenvolvidos respectivamente sob condições escura e de luz foram então selecionados para avaliação do teor de licopeno. Um método aperfeiçoado de cromatografia líquida de alto desempenho foi usado para a determinação química seletiva do teor de licopeno. A produção de licopeno induzida sob luz e também o nível máximo de licopeno incubado em luz foi mais alto do que aqueles incubados no escuro. As melhores taxas de crescimento de calo e suspensões de células foram obtidas respectivamente em meio WPM e B5. A produção de licopeno dependeu do crescimento como demonstrado pela análise do crescimento e teor de licopeno de ambos calos e cultura de células em suspensão

Vitrification of carnation in vitro: Changes in cell wall mechanical properties, cellulose and lignin content

peer reviewedVitrification of internodes of carnation was brought about by culturing in liquid medium. Cell wall extensibility of these internodes was kinetically followed in comparison to that of normal plants using the constant stress method. Liquid culture induced increased immediate and total deformation capacities of the walls from the second day. Measurements indicated that these deformation capacities involved plastic properties rather than elastic ones. These changes were paralleled by decreased relative levels of cellulose and lignin. © 1987 Martinus Nijhoff/Dr W. Junk Publishers