Abstract
Epidemiological studies on the effects of green tea consumption (Camellia sinensis) have demonstrated a reduction for the risk of age-related diseases. The investigation of the in vivo and in vitro antioxidant properties of an aqueous extract of green tea (GTE) was the aim of the current study. 2,2-Diphenyl-1-picrylhydrazyl (DPPH•) and superoxide anion radical (O2•−) assays were used to estimate the GTE antioxidant activity. To investigate the protective effects of GTE against oxidative stress, wild-type N2 and transgenic strains (TJ374, hsp-16.2/GFP) of the model organism, Caenorhabditis elegans (C. elegans), were chosen. In the current study, the following catechins were identified by LC/ESI-MS: catechin, epicatechin, epicatechin gallate, gallocatechin, epigallocatechin and epigallocatechin gallate. GTE exhibited a free radical scavenging activity of DPPH• and O2•− with IC50 8.37 and 91.34 µg/mL, respectively. In the C. elegans strain (TJ374, hsp-16.2/GFP), the expression of hsp-16.2/GFP was induced by a nonlethal dose of juglone, and the fluorescence density of hsp-16.2/GFP was measured. The hsp-16.2/GFP was reduced by 68.43% in the worms pretreated with 100 µg/mL GTE. N2 worms pretreated with 100 µg/mL GTE exhibited an increased survival rate of 48.31% after a lethal dose application of juglone. The results suggest that some green tea constituents are absorbed by the worms and play a substantial role to enhance oxidative stress resistance in C. elegans.
Highlights
Reactive oxygen species (ROS) are important molecules in biological systems, which are produced as by-products of normal metabolism
The present study aimed to investigate the ability of an aqueous extract of green tea (GTE) to scavenge the free radicals in vitro and to elucidate the effect of GTE treatment on oxidative stress resistance in C. elegans
The mean and standard error were calculated for each concentration
Summary
Reactive oxygen species (ROS) are important molecules in biological systems, which are produced as by-products of normal metabolism. DAF-16 from cytoplasm into nucleus in the TJ356 (DAF-16/GFP) strain [37] Catechin, another constituent from green tea, can extend the lifespan in C. elegans and increase its stress resistance by modulating the energy-intensive stress response and repair system [38], which is in agreement with the Disposable Soma Theory [39]. The present study aimed to investigate the ability of an aqueous extract of green tea (GTE) to scavenge the free radicals in vitro and to elucidate the effect of GTE treatment on oxidative stress resistance in C. elegans. The transgenic strain, TJ374 (hsp-16.2/GFP), of the model organism, C. elegans, was used to investigate the ability of GTE to be absorbed by C. elegans and to protect the worms against oxidative stress. This strain is a useful tool to monitor the oxidative stress effects in living organism, since hsp-16.2/GFP is used as a marker for the oxidative stress
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