Pyrogallol(pyrogallic acid)is easy to be autooxidized,forming a free radical under alkaline condition,but the mechanism has not been clear.The mechanism of the autooxidation of pyrogallol was studied with ESR,UV and N...Pyrogallol(pyrogallic acid)is easy to be autooxidized,forming a free radical under alkaline condition,but the mechanism has not been clear.The mechanism of the autooxidation of pyrogallol was studied with ESR,UV and NMR techniques and it was found that pyrogallol was autooxidized to a quinone radical under alkaline condition.And at the same time oxygen recieved an electron from the reaction to form superoxide anions,the hydroxyl free radical was then produced by HaberWeiss reaction.The oxygen free radicals generated from this process promoted the autooxidation of pyrogallol.展开更多
β-amyloid (Aβ) and copper play important roles in the pathogenesis of Alzheimer’s disease (AD).However,the behavioral correlativity and molecular mechanisms of Aβ and copper toxicity have been investigated less of...β-amyloid (Aβ) and copper play important roles in the pathogenesis of Alzheimer’s disease (AD).However,the behavioral correlativity and molecular mechanisms of Aβ and copper toxicity have been investigated less often.In the present study,we investigated the interaction and toxicity of Aβ1-42 and copper in the Aβ1-42 transgenic Caenorhabditis elegans worm model CL2006.Our data show that the paralysis behavior of CL2006 worms significantly deteriorated after exposure to 10-3 mol L-1 copper ions.However,the paralysis behavior was dramatically attenuated with exposure to 10-4 mol L-1 copper ions.The exogenous copper treatment also partially changed the homeostatic balance of zinc,manganese,and iron.Our data suggest that the accumulation of reactive oxygen species (ROS) was responsible for the paralysis induced by Aβ and copper in CL2006.The ROS generation induced by Aβ and copper appear to be through sod-1,prdx-2,skn-1,hsp-60 and hsp-16.2 genes.展开更多
Epidemiological evidence and experimental studies suggest that drinking green tea is associated with a lower risk of obesity and related diseases. However, the mechanisms of these effects are not clear. In the present...Epidemiological evidence and experimental studies suggest that drinking green tea is associated with a lower risk of obesity and related diseases. However, the mechanisms of these effects are not clear. In the present study, we investigated the anti-obesity mechanisms of green tea catechins (GTCs) through modulation of peroxisome proliferator activated-receptor (PPAR) pathways in high-fat diet-induced obesity in rats. GTC supplementation significantly attenuated the increased body and liver weights and the elevated serum and liver triglyceride levels. Meanwhile, GTCs increased the PPARγ levels in subcutaneous white adipose tissue (SWAT) and decreased the PPAR levels in visceral white adipose tissue (VWAT). In addition, GTC treatment up-regulated the levels of PPARδ in SWAT, VWAT, and brown adipose tissue and increased the expression of genes involved in fatty acid oxidation in brown adipose tissue. Our results suggest that GTCs exert their anti-obesity mechanism in part by modulating PPAR signaling pathways.展开更多
In this study, the inhibitory effect of L-theanine, an amino acid derivative of tea, on the rewarding effects of nicotine and its underlying mechanisms of action were studied. We found that L-theanine inhibited the re...In this study, the inhibitory effect of L-theanine, an amino acid derivative of tea, on the rewarding effects of nicotine and its underlying mechanisms of action were studied. We found that L-theanine inhibited the rewarding effects of nicotine in a con- ditioned place preference （CPP） model of the mouse and reduced the excitatory status induced by nicotine in SH-SY5Y cells to the same extent as the nicotine receptor inhibitor dihydro-beta-erythroidine （DHI3E）. Further studies using high performance liquid chromatography, western blotting and immunofluorescence staining analyses showed that L-theanine significantly in- hibited nicotine-induced tyrosine hydroxylase （TH） expression and dopamine production in the midbrain of mice. L-theanine treatment also reduced the upregulation of the ~4,132 and c^7 nicotine acetylcholine receptor （nAChR） subunits induced by nico- tine in mouse brain regions that related to the dopamine reward pathway, thus decreasing the number of cells that could react to nicotine. In addition, L-theanine treatment inhibited nicotine-induced c-Fos expression in the reward circuit related areas of the mouse brain. Knockdown of c-Fos by siRNA inhibited the excitatory status of cells but not the upregulation of TH induced by nicotine in SH-SY5Y cells. Overall, the present study showed that L-theanine reduced the nicotine-induced reward effects via inhibition of the nAChR-dopamine reward pathway. These results may offer new therapeutic strategies for treatment of to- bacco addiction.展开更多
Site-directed spin labeling (SDSL) is a powerful tool for monitoring protein structure, dynamics and conformational changes. In this study, the domain-specific properties of azurin and its interaction with p53 were st...Site-directed spin labeling (SDSL) is a powerful tool for monitoring protein structure, dynamics and conformational changes. In this study, the domain-specific properties of azurin and its interaction with p53 were studied using this technique. Mutations of six residues, that are located in the hydrophobic patch of azurin, were prepared and spin labeled. Spectra of the six azurin mutants in solution showed that spin labeled residues 45 and 63 are in a very restricted environment, residues 59 and 65 are in a spacious environment and have free movement, and residues 49 and 51 are located in a relatively closed pocket. Polarity experiments confirmed these results. The changes observed in the spectra of spin labeled azurin upon interaction with p53 indicate that the hydrophobic patch is involved in this interaction. Our results provide valuable insight into the topographic structure of the hydrophobic domain of azurin, as well as direct evidence of its interaction with p53 in solution via the hydrophobic patch. Cytotoxicity studies of azurin mutants showed that residues along the hydrophobic patch are important for its cytotoxicity.展开更多
文摘Pyrogallol(pyrogallic acid)is easy to be autooxidized,forming a free radical under alkaline condition,but the mechanism has not been clear.The mechanism of the autooxidation of pyrogallol was studied with ESR,UV and NMR techniques and it was found that pyrogallol was autooxidized to a quinone radical under alkaline condition.And at the same time oxygen recieved an electron from the reaction to form superoxide anions,the hydroxyl free radical was then produced by HaberWeiss reaction.The oxygen free radicals generated from this process promoted the autooxidation of pyrogallol.
基金supported by the National Natural Science Foundation of China (Grant No. 30870578)the National Basic Research Program of China (Grant No. 2006CB500700)funded by the US National Institutes of Health for providing nematode strains used in this work
文摘β-amyloid (Aβ) and copper play important roles in the pathogenesis of Alzheimer’s disease (AD).However,the behavioral correlativity and molecular mechanisms of Aβ and copper toxicity have been investigated less often.In the present study,we investigated the interaction and toxicity of Aβ1-42 and copper in the Aβ1-42 transgenic Caenorhabditis elegans worm model CL2006.Our data show that the paralysis behavior of CL2006 worms significantly deteriorated after exposure to 10-3 mol L-1 copper ions.However,the paralysis behavior was dramatically attenuated with exposure to 10-4 mol L-1 copper ions.The exogenous copper treatment also partially changed the homeostatic balance of zinc,manganese,and iron.Our data suggest that the accumulation of reactive oxygen species (ROS) was responsible for the paralysis induced by Aβ and copper in CL2006.The ROS generation induced by Aβ and copper appear to be through sod-1,prdx-2,skn-1,hsp-60 and hsp-16.2 genes.
基金supported by the National Natural Science Foundation of China (30170239, 30930036)
文摘Epidemiological evidence and experimental studies suggest that drinking green tea is associated with a lower risk of obesity and related diseases. However, the mechanisms of these effects are not clear. In the present study, we investigated the anti-obesity mechanisms of green tea catechins (GTCs) through modulation of peroxisome proliferator activated-receptor (PPAR) pathways in high-fat diet-induced obesity in rats. GTC supplementation significantly attenuated the increased body and liver weights and the elevated serum and liver triglyceride levels. Meanwhile, GTCs increased the PPARγ levels in subcutaneous white adipose tissue (SWAT) and decreased the PPAR levels in visceral white adipose tissue (VWAT). In addition, GTC treatment up-regulated the levels of PPARδ in SWAT, VWAT, and brown adipose tissue and increased the expression of genes involved in fatty acid oxidation in brown adipose tissue. Our results suggest that GTCs exert their anti-obesity mechanism in part by modulating PPAR signaling pathways.
基金supported by the National Natural Science Foundation of China (Grant No. 30870587)National Basic Research Program of China from the Department of Science and Technology of China(Grant No. 2006CB500700)
文摘In this study, the inhibitory effect of L-theanine, an amino acid derivative of tea, on the rewarding effects of nicotine and its underlying mechanisms of action were studied. We found that L-theanine inhibited the rewarding effects of nicotine in a con- ditioned place preference （CPP） model of the mouse and reduced the excitatory status induced by nicotine in SH-SY5Y cells to the same extent as the nicotine receptor inhibitor dihydro-beta-erythroidine （DHI3E）. Further studies using high performance liquid chromatography, western blotting and immunofluorescence staining analyses showed that L-theanine significantly in- hibited nicotine-induced tyrosine hydroxylase （TH） expression and dopamine production in the midbrain of mice. L-theanine treatment also reduced the upregulation of the ~4,132 and c^7 nicotine acetylcholine receptor （nAChR） subunits induced by nico- tine in mouse brain regions that related to the dopamine reward pathway, thus decreasing the number of cells that could react to nicotine. In addition, L-theanine treatment inhibited nicotine-induced c-Fos expression in the reward circuit related areas of the mouse brain. Knockdown of c-Fos by siRNA inhibited the excitatory status of cells but not the upregulation of TH induced by nicotine in SH-SY5Y cells. Overall, the present study showed that L-theanine reduced the nicotine-induced reward effects via inhibition of the nAChR-dopamine reward pathway. These results may offer new therapeutic strategies for treatment of to- bacco addiction.
基金supported by the National Natural Science Foundation of China (Grant No. 30370361)the National Basic Research Program of China (Grant No. 2006CB500700)supported by the Key Laboratory of Mental Health, Chinese Academy of Sciences
文摘Site-directed spin labeling (SDSL) is a powerful tool for monitoring protein structure, dynamics and conformational changes. In this study, the domain-specific properties of azurin and its interaction with p53 were studied using this technique. Mutations of six residues, that are located in the hydrophobic patch of azurin, were prepared and spin labeled. Spectra of the six azurin mutants in solution showed that spin labeled residues 45 and 63 are in a very restricted environment, residues 59 and 65 are in a spacious environment and have free movement, and residues 49 and 51 are located in a relatively closed pocket. Polarity experiments confirmed these results. The changes observed in the spectra of spin labeled azurin upon interaction with p53 indicate that the hydrophobic patch is involved in this interaction. Our results provide valuable insight into the topographic structure of the hydrophobic domain of azurin, as well as direct evidence of its interaction with p53 in solution via the hydrophobic patch. Cytotoxicity studies of azurin mutants showed that residues along the hydrophobic patch are important for its cytotoxicity.
