The time resolved transient absorption property, kinetics and mechanism of electron transfer(ET) process of the fluorescence probe, N-(2-hydroxyethyl)-1,8-naphthalimide(NPI) were studied. The transient absorption sp...The time resolved transient absorption property, kinetics and mechanism of electron transfer(ET) process of the fluorescence probe, N-(2-hydroxyethyl)-1,8-naphthalimide(NPI) were studied. The transient absorption spectra of NPI in H 2O-CH 3CN solution were successfully detected upon pulsed excitation at 355 nm. 3NPI was proved as the primary excited state with lifetime of 147 μs. 3NPI underwent the T-T energy transfer with β-carotene and ET with triphenyl amine to produce NPI -·. In the absence of quenchers, the self-quenching of 3NPI by the ground states of NPI took place via ET. The ET from nucleosides to 3NPI was also explored. NPI showed a strong electron-accepting capability and the absorbance of 3NPI was strongly quenched by the nucleosides. The formation of NPI -· was facilitated to a great extent simultaneously. The bimolecular quenching rate constants of NPI by GUA and DGUA were determined as k 3=8.8×106 mol -1·L·s -1, k 4=2.1×107 mol·L·s -1. The ET between NPI and nucleosides was verified and the mechanism was proposed.展开更多
Oxidative stress is a health condition that could potentially harm the patient, and it is defined as the lack of balance between the production of oxygen free radicals, which rises, and antioxidant defenses, which are...Oxidative stress is a health condition that could potentially harm the patient, and it is defined as the lack of balance between the production of oxygen free radicals, which rises, and antioxidant defenses, which are in decrease. Metabolic syndrome implies a variety of risk factors that are based on abdominal obesity and insulin resistance. Moreover, the importance of metabolic syndrome is emphasized due to the fact that it presents an increase in oxidative stress, which is produced by the sum of alterations that each risk factor produces within the metabolic syndrome pathology. Reducing oxidative stress in these patients is currently one of the most interesting challenges of cardiovascular and metabolic therapeutics, because it is a molecular biology alteration that is not generally diagnosed and, therefore, not treated. The increasing incidence of overweight and obesity cause an increase in the incidence of metabolic syndrome, thus turning into a huge problem that keeps growing at alarming proportions. This syndrome＇s incidence oscillates between 20 and 40%, depending on the gender, age, ethnic group, and diagnostic criteria used for the definition of the disease. Prospective studies show that metabolic syndrome doubles the risk of cardiovascular disease and causes a five-fold increase in the risk of developing type 2 diabetes. With the aim of decreasing the oxidative stress caused by metabolic syndrome, we investigated the effect of antioxidant protection in DNA repair and cell membranes through the use of blueberry extract, which is the fruit with the highest antioxidant capacity, in patients with metabolic syndrome. Thirty patients were studied for a period of 6 months of intervention, and it could be demonstrated that they showed a highly significant decrease in the damage produced to the DNA, which was measured by the urinary excretion of 8-hydroxy-2＇-deoxyguanosine （8-OHdG） and the damage caused to the vascular endothelium and cell membranes, which was measured through the urinary excretion of F2-isoprostane. Based on our knowledge, this investigation is the first one to show that lyophilized blueberry extract （BlueKing~） as a dietary supplement, with meals, is an additional therapeutic tool of great value for the treatment of oxidative stress through DNA and cell membrane protection in patients with metabolic syndrome.展开更多
To improve the stability and pharmacokinetic properties,prodrugs of L-ddG（L-2＇,3＇-dideoxy-guanosine）and L-D4G （L-2＇,3＇-dihydro-2＇,3＇-dideoxyguanosine）modified with a series of substituted amino groups at C-6...To improve the stability and pharmacokinetic properties,prodrugs of L-ddG（L-2＇,3＇-dideoxy-guanosine）and L-D4G （L-2＇,3＇-dihydro-2＇,3＇-dideoxyguanosine）modified with a series of substituted amino groups at C-6 position of the purine base were designed and synthesized and their anti-HIV activities were evaluated.Compounds 7d and 8g exhibited moderate activity and showed EC_（50）of 42μmol/L and 55μmol/L,respectively.展开更多
文摘The time resolved transient absorption property, kinetics and mechanism of electron transfer(ET) process of the fluorescence probe, N-(2-hydroxyethyl)-1,8-naphthalimide(NPI) were studied. The transient absorption spectra of NPI in H 2O-CH 3CN solution were successfully detected upon pulsed excitation at 355 nm. 3NPI was proved as the primary excited state with lifetime of 147 μs. 3NPI underwent the T-T energy transfer with β-carotene and ET with triphenyl amine to produce NPI -·. In the absence of quenchers, the self-quenching of 3NPI by the ground states of NPI took place via ET. The ET from nucleosides to 3NPI was also explored. NPI showed a strong electron-accepting capability and the absorbance of 3NPI was strongly quenched by the nucleosides. The formation of NPI -· was facilitated to a great extent simultaneously. The bimolecular quenching rate constants of NPI by GUA and DGUA were determined as k 3=8.8×106 mol -1·L·s -1, k 4=2.1×107 mol·L·s -1. The ET between NPI and nucleosides was verified and the mechanism was proposed.
文摘Oxidative stress is a health condition that could potentially harm the patient, and it is defined as the lack of balance between the production of oxygen free radicals, which rises, and antioxidant defenses, which are in decrease. Metabolic syndrome implies a variety of risk factors that are based on abdominal obesity and insulin resistance. Moreover, the importance of metabolic syndrome is emphasized due to the fact that it presents an increase in oxidative stress, which is produced by the sum of alterations that each risk factor produces within the metabolic syndrome pathology. Reducing oxidative stress in these patients is currently one of the most interesting challenges of cardiovascular and metabolic therapeutics, because it is a molecular biology alteration that is not generally diagnosed and, therefore, not treated. The increasing incidence of overweight and obesity cause an increase in the incidence of metabolic syndrome, thus turning into a huge problem that keeps growing at alarming proportions. This syndrome＇s incidence oscillates between 20 and 40%, depending on the gender, age, ethnic group, and diagnostic criteria used for the definition of the disease. Prospective studies show that metabolic syndrome doubles the risk of cardiovascular disease and causes a five-fold increase in the risk of developing type 2 diabetes. With the aim of decreasing the oxidative stress caused by metabolic syndrome, we investigated the effect of antioxidant protection in DNA repair and cell membranes through the use of blueberry extract, which is the fruit with the highest antioxidant capacity, in patients with metabolic syndrome. Thirty patients were studied for a period of 6 months of intervention, and it could be demonstrated that they showed a highly significant decrease in the damage produced to the DNA, which was measured by the urinary excretion of 8-hydroxy-2＇-deoxyguanosine （8-OHdG） and the damage caused to the vascular endothelium and cell membranes, which was measured through the urinary excretion of F2-isoprostane. Based on our knowledge, this investigation is the first one to show that lyophilized blueberry extract （BlueKing~） as a dietary supplement, with meals, is an additional therapeutic tool of great value for the treatment of oxidative stress through DNA and cell membrane protection in patients with metabolic syndrome.
基金National Natural Science Foundation of China (Grant No.20472006 and 20832001)
文摘To improve the stability and pharmacokinetic properties,prodrugs of L-ddG（L-2＇,3＇-dideoxy-guanosine）and L-D4G （L-2＇,3＇-dihydro-2＇,3＇-dideoxyguanosine）modified with a series of substituted amino groups at C-6 position of the purine base were designed and synthesized and their anti-HIV activities were evaluated.Compounds 7d and 8g exhibited moderate activity and showed EC_（50）of 42μmol/L and 55μmol/L,respectively.
