Abril-Junio 2021 86
ISSN 1317-987X


Inhibición del estrés oxidativo inducido con peróxido de hidrógeno en Saccharomyces cerevissiae (evaluación de un extracto acuoso de Camellia sinensis)

Materials and methods

Origin of plant material (PM)

Non-commercial organic green tea from China, stored in its package until analysis.

Sample preparation for extraction

2 grams of plant material were weighed. This was poured into a 400 mL Beaker, to which 200 mL of distilled water previously heated to the boiling point was added. The sample was slightly stirred for 4 min and filtered using Whatman No. 4 paper (8).

Figure 1. Aqueous extract of Camellia sinensis. Agitation prior to evaluation

Determination of total phenolics

For the determination of total phenolics, 50 μL were mixed with 250 μL of the Folin-Ciocalteu 1 N reagent (Analytical grade, Merck). It was left to stand for 8 minutes and then 750 μL of 20% Na2CO3 and 950 μL of distilled water were added. Was incubated for 30 min at room temperature and the absorbance was read on a Genesis 20 UV/VIS spectrophotometer (Thermo Scientific, Waltham, Massachusetts, USA). A calibration curve for Gallic Acid (Sigma-Aldrich, Germany) was prepared with concentrations of 50, 100, 200, 300, 400, 500 and 1000 ppm. The results were expressed in mg of Gallic Acid Equivalents (GAE) / g of PM (9).

Biological effects in cell model (S. cerevisiae-oxidative stress with H2O2)

This essay seeks to evaluate the ability of the compounds present in the extracts to promote the growth of yeast when subjected to oxidative stress with hydrogen peroxide, for which the following experimental sequence was carried out (10): The positive control with ascorbic acid, the negative without antioxidant and a blank only with yeast and culture medium. Before starting the absorbance measurements, S. cerevisiae was inoculated for 24 h under agitation at 37 ° C with 8 mL of YPD culture medium (peptone 2% w / v, glucose 2% w / v), 25 μL of yeast stock (solution of S. cerevisiae with a cell concentration of 5.3 x 105 cells / mL), 100 μL of ascorbic acid and 80 μL of the extract of the samples. In control negative and white were inoculated only 8 mL of YPD and 25 μL of the yeast stock. After this incubation time of the yeast under the different conditions the absorbance was measured at 600 nm, this was approximately 0.240 and corresponded to the starting point of latency period of S. cerevisiae. Then 160 were added μL of 0.8 mM H2O2 to the positive control, negative and the extract to be evaluated at different concentrations. It was incubated at 37 ° C under stirring for 8 h and readings were taken every 30 min. Before each reading they waved the glass tubes for 10 s in vortex to ensure the homogeneity of the cells in the culture medium, then 100 μL of each test was taken and then taken to plates 96 wells orbital shaking was performed before each reading 20 s and the absorbance readings were taken at 600 nm.

Statistical analysis

Analyses were done in triplicate, and the results were expressed as means ± standard deviation (SD). Results of antioxidant activity were each subjected to analysis of variance (ANOVA).

Continua: Results

Inhibición del estrés oxidativo inducido con peróxido de hidrógeno en Saccharomyces cerevissiae (evaluación de un extracto acuoso de Camellia sinensis)
Materials and methods
Discussion and conclusions

NOTA: Toda la información que se brinda en este artículo es de carácter investigativo y con fines académicos y de actualización para estudiantes y profesionales de la salud. En ningún caso es de carácter general ni sustituye el asesoramiento de un médico. Ante cualquier duda que pueda tener sobre su estado de salud, consulte con su médico o especialista.

Instituto de Medicina Tropical - Facultad de Medicina - Universidad Central de Venezuela.
Elaborado por el Centro de Análisis de Imágenes Biomédicas Computarizadas CAIBCO,
Este portal ha sido desarrollado gracias al apoyo del Fonacit