Scientists have long been interested in the synthesis and medical use of 4’-thionudeosides. However, their effect on DNA synthesis has not been well studied. In order to study their bioactivity and explore new applic...Scientists have long been interested in the synthesis and medical use of 4’-thionudeosides. However, their effect on DNA synthesis has not been well studied. In order to study their bioactivity and explore new applications, we have synthesized 4’-thio-2’-deoxythymidine-5’-triphosphate (T’TP). The experimental results obtained in our lab showed that T’TP is a strong inhibitor of DNA polymerase, and the inhibition is highly specific. These prbperties indicate the potential of T’TP used for antitumor and antiviral agents as well as for the terminator in DNA sequencing.展开更多
Background: Molnupiravir, N4-hydroxycytidine-5’-isopropyl ester, is an oral prodrug of N4-deoxycytidine (NHC), a nucleoside analog, which has in vitro activity against SARS-CoV-2. NHC is phosphorylated in cells to NH...Background: Molnupiravir, N4-hydroxycytidine-5’-isopropyl ester, is an oral prodrug of N4-deoxycytidine (NHC), a nucleoside analog, which has in vitro activity against SARS-CoV-2. NHC is phosphorylated in cells to NHC triphosphate (NHC-TP), which is incorporated into viral RNA, leading to epigenetic catastrophe of the viral genome and inhibition of viral replication. The antiviral activity against SARS-CoV-2 is dependent on the number of molecules of NHC-TP incorporated into viral RNA. Clinical studies in patients with COVID-19 showed that treatment with molnupiravir for 5 days decreases the risk of hospitalization and death as compared with placebo. Objective: It should be possible to enhance the antiviral activity of NHC-TP against SARS-CoV-2 by the use of the biochemical modulator, 3-deazauridine (3DU). 3DU is an inhibitor of CTP synthetase. Inhibition of this enzyme results in a reduction in the intracellular pool size of CTP. Since NHC-TP competes with CTP for incorporation into viral RNA in the reaction catalyzed by the SARS-CoV-2 viral RNA-dependent RNA polymerase, the reduction in the level of CTP should result in a significant enhancement of the incorporation of NHC-TP into viral RNA and an enhancement of its antiviral activity. Methods: Analysis of the publications of 3DU and cytosine nucleoside analogues support the hypothesis that 3DU enhances the pharmacological action of the analogues. Results: 3-DU increased the incorporation of 5-azacytidine into RNA and 5-aza-deoxycytidine into DNA of leukemic cells with an enhancement of their antineoplastic action. 3-DU potentiated the antiviral activity against HIV-1 activity by the cytosine nucleoside analogues: 2’-deoxy-3’-thiacytidine (3TC;lamivudine) and 2’,3’-dideoxycytidine (ddC). This anti-HIV-1 activity of 3DU was associated with a reduction in the intracellular pool size of dCTP and increased incorporation of triphosphates of 3TC and ddC into DNA by the HIV-1 reverse transcriptase. The reduction of CTP levels in cells by 3-DU also leads to a reduction in dCTP since CTP is its precursor. Conclusion: The preclinical studies on 3-DU indicate that it can enhance the pharmacological activity of both ribo- and deoxyribonucleoside analogues against neoplastic cells and viral infected cells. These observations suggest that 3-DU also has the potential to enhance the antiviral activity of molnupiravir and arrest the progression of the disease in patients with COVID-19.展开更多
In this paper, some new results on the selective weak interaction between Na-4-tosyl-L-arginine methyl ester hydrochloride （TAME） and adenosine-5＇-triphosphate （ATP） have been reported. Fluorescence spectrophotom...In this paper, some new results on the selective weak interaction between Na-4-tosyl-L-arginine methyl ester hydrochloride （TAME） and adenosine-5＇-triphosphate （ATP） have been reported. Fluorescence spectrophotometry and Fourier transform infrared （FT-IR） spectroscopy were used to investigate this kind of weak interaction. In fluorescence experiments, obvious fluorescence quenching phenomena were observed when TAME was added, which indicated the weak interactions between TAME and ATP. It has been identified by fluorescence titration experiments that TAME exhibited high selectivity to ATP over ADP and AMP. FT-IR spectral results showed that an ATP-TAME adduct was formed. The experimental results indicated that the interaction sites were the guanidinium group of TAME main-chain and the γ-phosphate group of ATP, and the interaction took place through hydrogen bonding and electrostatic force. In addition, the effects of metal ions on the weak interaction between ATP and TAME, or between ATP and analogues of L-arginine were studied.展开更多
文摘Scientists have long been interested in the synthesis and medical use of 4’-thionudeosides. However, their effect on DNA synthesis has not been well studied. In order to study their bioactivity and explore new applications, we have synthesized 4’-thio-2’-deoxythymidine-5’-triphosphate (T’TP). The experimental results obtained in our lab showed that T’TP is a strong inhibitor of DNA polymerase, and the inhibition is highly specific. These prbperties indicate the potential of T’TP used for antitumor and antiviral agents as well as for the terminator in DNA sequencing.
文摘Background: Molnupiravir, N4-hydroxycytidine-5’-isopropyl ester, is an oral prodrug of N4-deoxycytidine (NHC), a nucleoside analog, which has in vitro activity against SARS-CoV-2. NHC is phosphorylated in cells to NHC triphosphate (NHC-TP), which is incorporated into viral RNA, leading to epigenetic catastrophe of the viral genome and inhibition of viral replication. The antiviral activity against SARS-CoV-2 is dependent on the number of molecules of NHC-TP incorporated into viral RNA. Clinical studies in patients with COVID-19 showed that treatment with molnupiravir for 5 days decreases the risk of hospitalization and death as compared with placebo. Objective: It should be possible to enhance the antiviral activity of NHC-TP against SARS-CoV-2 by the use of the biochemical modulator, 3-deazauridine (3DU). 3DU is an inhibitor of CTP synthetase. Inhibition of this enzyme results in a reduction in the intracellular pool size of CTP. Since NHC-TP competes with CTP for incorporation into viral RNA in the reaction catalyzed by the SARS-CoV-2 viral RNA-dependent RNA polymerase, the reduction in the level of CTP should result in a significant enhancement of the incorporation of NHC-TP into viral RNA and an enhancement of its antiviral activity. Methods: Analysis of the publications of 3DU and cytosine nucleoside analogues support the hypothesis that 3DU enhances the pharmacological action of the analogues. Results: 3-DU increased the incorporation of 5-azacytidine into RNA and 5-aza-deoxycytidine into DNA of leukemic cells with an enhancement of their antineoplastic action. 3-DU potentiated the antiviral activity against HIV-1 activity by the cytosine nucleoside analogues: 2’-deoxy-3’-thiacytidine (3TC;lamivudine) and 2’,3’-dideoxycytidine (ddC). This anti-HIV-1 activity of 3DU was associated with a reduction in the intracellular pool size of dCTP and increased incorporation of triphosphates of 3TC and ddC into DNA by the HIV-1 reverse transcriptase. The reduction of CTP levels in cells by 3-DU also leads to a reduction in dCTP since CTP is its precursor. Conclusion: The preclinical studies on 3-DU indicate that it can enhance the pharmacological activity of both ribo- and deoxyribonucleoside analogues against neoplastic cells and viral infected cells. These observations suggest that 3-DU also has the potential to enhance the antiviral activity of molnupiravir and arrest the progression of the disease in patients with COVID-19.
基金Project supported by the National Natural Science Foundation of China （No. 90210027）.Acknowledgments The authors especially thank Zhide Hu in Lanzhou University for kindly allowing the use of the RF-5301PC spectrofluorophotometer （Shimadzu） in this work and Wenying He in Lanzhou University for active discussion as well as zealous help during the fluorescence experiments.
文摘In this paper, some new results on the selective weak interaction between Na-4-tosyl-L-arginine methyl ester hydrochloride （TAME） and adenosine-5＇-triphosphate （ATP） have been reported. Fluorescence spectrophotometry and Fourier transform infrared （FT-IR） spectroscopy were used to investigate this kind of weak interaction. In fluorescence experiments, obvious fluorescence quenching phenomena were observed when TAME was added, which indicated the weak interactions between TAME and ATP. It has been identified by fluorescence titration experiments that TAME exhibited high selectivity to ATP over ADP and AMP. FT-IR spectral results showed that an ATP-TAME adduct was formed. The experimental results indicated that the interaction sites were the guanidinium group of TAME main-chain and the γ-phosphate group of ATP, and the interaction took place through hydrogen bonding and electrostatic force. In addition, the effects of metal ions on the weak interaction between ATP and TAME, or between ATP and analogues of L-arginine were studied.
