Effect of green tea extract on the maintenance of genome stability in yeast
Date Issued
2010
Date
2010
Author(s)
Chiang, Hsin-Yi
Abstract
Green tea is renowned for containing rich polyphenols that are considered the anti-carcinogenic and anti-mutagenic agents. In this study, we investigated how green tea extract (GTE) affects yeast genome instability induced by UVB irradiation. Yeast was cultured in mediums with or without GTE. After UVB irradiation, the cells were collected for assays of survival, gene mutation, reactive oxygen species (ROS), cell cycle, and expressions of redox and repair genes. The reactive oxygen species (ROS) levels in cells were declined gradually after UVB exposure in GTE-treated group; nevertheless, an increasing trend was observed in control or EGCG or caffeine-treated group. However, the G1/S phase cell cycle arrest induced by UVB damage was unaffected by the addition of GTE. Furthermore, the gene expressions of antioxidative enzymes, TSA1, SOD1 and CTT1 were modulated by GTE. DNA-repair genes, RAD14 and RAD51, responsible for nucleotide excision repair and homologous recombination repair pathways respectively, were activated with GTE treatment. As a result, the cell survival rates were elevated while the gene mutation rates were decreased with the administration of GTE. In conclusion, we found that GTE had positive effects on the maintenance of genome stability in yeast through effectively lowering ROS levels, and activating redox and DNA repair systems. These results also demonstrate that yeast can be a powerful tool for distinguishing the biological functions of bioactive compounds.
Subjects
green tea extract
UVB irradiation
genome stability
DNA repair
ROS
Type
thesis
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