Nucleoside Research Articles

Simultaneous enrichment and sequential elution of cis-diol containing molecules and deoxyribonucleotides with bifunctional boronate and titanium (Ⅳ) ion modified-magnetic nanoparticles prior to quantitation by high performance liquid chromatography

Some diseases can cause abnormal concentrations of catecholamines (CAs), nucleosides (NSs) and nucleotides (NTs) in patients. Previous studies normally focused on the detection of the three types of substances separately. In this work, a bifunctional boronate and titanium (Ⅳ) ion affinity magnetic adsorbent with high-capacity was prepared. The adsorbent can simultaneously enrich CAs, NSs and NTs in a single extraction process, and the adsorbed analytes can be sequentially eluted by 1.0% trifluoroacetic acid and 20.0 mmol L−1 Na3PO4. An analytical method of the analytes has been established by coupling the adsorbent with RP-HPLC. The method has low detection limits (0.039–0.708 ng mL−1) and good reproducibility (inter- and intra-day of assay RSDs less than 15.0%). Serum sample from healthy volunteer was successfully quantified for two CAs, four NSs and five NTs. Compared with the reported methods, the proposed method is simpler to operate, consume less samples, and has enough accurate and sensitivity to obtain comprehensive information on the concentrations of analytes in a single extraction process.

Optimization of the Prodrug Moiety of Remdesivir to Improve Lung Exposure/Selectivity and Enhance Anti-SARS-CoV-2 Activity.

COVID-19 patients with severe symptoms still lack antiviral treatment options. Although remdesivir is the only FDA-approved drug for those patients, its efficacy is limited by premature hydrolysis to nucleoside (NUC), low accumulation in the disease-targeted tissue (lungs), and low antiviral potency. In this study, we synthesized a new series of remdesivir analogues by modifying the ProTide moiety. In comparison with remdesivir, the lead compound MMT5-14 showed 2- to 7-fold higher antiviral activity in four variants of SARS-CoV-2. By reducing premature hydrolysis in hamsters, MMT5-14 increased the prodrug concentration by 200- to 300-fold in the plasma and lungs but also enhanced lung accumulation of the active metabolite triphosphate nucleosides (NTP) by 5-fold. Compared to remdesivir, MMT5-14 also increased the intracellular uptake and activation in lung epithelial cells by 4- to 25-fold. These data suggest that MMT5-14 could be a potential antiviral drug to treat COVID-19 patients with severe symptoms.

Rovafovir Etalafenamide (Part IV): Synthesis of the Fluorinated Nucleoside Fragment

Rovafovir Etalafenamide (Part IV): Synthesis of the Fluorinated Nucleoside Fragment

Long-term outcome after prevention of de novo hepatitis B in recipients of core antibody-positive livers with hepatitis B immunoglobulin only

Background: Anti-HBc positive donors represent an important source of organs in hepatitis B virus (HBV) endemic areas despite the risk of occult HBV infection. We analyzed long-term outcome of prevention for de novo HBV with hepatitis B immunoglobulin (HBIG) only after liver transplantation (LT) using core-positive grafts. Methods: We retrospectively reviewed the prospective collected data of 1,479 recipients between 1988 and 2018 at Seoul Nation al University Hospital. 1,458 were eligible and enrolled. If either donor or recipient had core antibody, HBIG 4000 IU was adminis trated 4 times until postoperative day 3. Results: Of 1,458 LTs, 478 (32.8%) used anti-HBc positive grafts. Three hundred twenty-six (68.2%) was allocated to hepatitis B surface antigen (HBsAg)-positive recipients, with 152 (31.8%) to HBs-negative recipients. 21 (13.8%) of de novo HBV infection occurred in 152 core-positive grafts. One (25%), 11 (22.4%), 0, 9 (9.2%) was diagnosed of de novo HBV infection in 4 of hepatitis B surface antigen (HBcAb) and HBsAb negative, 49 of HBcAb-negative and HBsAb-positive, 1 of HBcAb-positive and HBsAb-neg ative, 98 of HBcAb and HBsAb positive recipients respectively. Anti-HBc negative recipients were more likely to develop de novo HBV infection compared with anti-HBc positive recipients (22.6% vs. 9.1%, P=0.021). Incidence of de novo HBV infection did not differ by recipient HBsAb status (P=0.530). The median follow-up time was 69 months (range, 29-165 months). The median time to detection of HBsAg seropositivity was 18 months (range, 8-55 months). Two had no treatment, twelve were treated with nu cleoside analogs (NA) monotherapy, and seven were treated with NA plus HBIG. The median treatment duration was 41 months. Seven acquired seroconversion. There were 42 (8.8%) of graft losses in study period. The 1-, 5-, 10-year patient survival with an ti-HBc positive liver were 97.5%, 93.2%, and 90.5%. No patient died of de novo HBV infection. Conclusions: De novo HBV did not affect patient survival. However, HBIG only prophylaxis was not enough to prevent de novo HBV development in the era of NA.

DNA drug resistance and subtypes in HIV-1 patients receiving antiretroviral therapy in Fuxin, Liaoning

Objective To investigate the prevalence of HIV resistant strains and distribution of subtypes in patients receiving HAART in Fuxin. Methods The whole blood samples were collected for leukocyte enrichment, and its DNA were extracted from each sample. The HIV-1 pol gene was amplified by nested-PCR and the PCR products were subjected to sequencing. The sequences was analyzed by the software MEGA and online tool HIV Drug Resistance Database provided by Stanford University. Results Pol gene fragments were successfully amplified in 101 from 112 samples, of which CRF01_AE accounted for 84.16%(85/101), CRF07_BC 8.91%(9/101), B 3.96%(4/101), CRF65_cpx 1.98%(2/101) and G 0.99%(1/101); 27 samples with drug resistant mutations were found, 19 of them were resistant to Nucleoside Reverse Transcriptase Inhibitors and the main mutation site was M184I/V, 14 of them were resistant to Non Nucleoside Reverse Transcriptase Inhibitors and the main mutation site was G190S, 6 of them were resistant to both Nucleoside Reverse Transcriptase Inhibitors and Non Nucleoside Reverse Transcriptase Inhibitors, none of them was resistant to Protease Inhibitos; There were significant differences in treatment time and baseline CD4 levels. Conclusion There are five subtypes of HIV-1 in Fuxin City, with CRF01_AE as the major subtype. The research to drug resistance provides reference for guiding AIDS prevention and treatment more scientifically and effectively. It is necessary to strengthen the monitoring of drug resistance and baseline data to strictly prevent the spread of resistant mutant. 摘要：目的 了解阜新市已接受 HAART 患者 HIV 耐药株的发生及基因亚型分布情况。 方法 采集全血标本进行 白细胞富集和前病毒 DNA 提取, 巢式 PCR 扩增 HIV-1 pol 区基因并测序, 使用 MEGA 以及斯坦福大学 HIV 耐药数据库 等工具对序列信息进行分析。 结果 在 112 份全血标本中获得 101 例有效基因序列, CRF01_AE 亚型占 84.16% (85/ 101) , CRF07_BC 亚型占 8.91% (9/101) , B 亚型占 3.96% (4/101) , CRF65_cpx 亚型占 1.98% (2/101) , G 亚型 0.99% (1/101) ; 耐药分析显示 27 例患者发生耐药位点突变, 其中, 19 例对核苷类逆转录酶抑制剂耐药, 主要耐药突变位点为 M184I/V, 14 例对非核苷类逆转录酶抑制剂耐药, 主要耐药突变位点为 G190S, 对两类逆转录酶抑制剂同时耐药的样本 有 6 例, 尚未出现蛋白酶抑制剂耐药突变患者; 治疗时间以及基线 CD4 水平的差异对耐药突变具有统计学意义。 结论 阜新市 HIV-1 存在 5 种亚型, CRF01_AE 为主要流行亚型; 耐药情况的研究为更科学有效地指导艾滋病防治工 作提供参考依据, 应继续加强耐药监测, 掌握基线数据, 严防耐药株的流行。

One, Two, Three – Nucleosides

One, Two, Three – Nucleosides

Experience with Dolutegravir plus Boosted Darunavir as a Switch Option

Interest continues in finding long-term antiretroviral treatment (ART) strategies involving two-drug regimens and nucleoside reverse transcriptase

Front Cover: Spectral Unmixing‐Based Reaction Monitoring of Transformations between Nucleosides and Nucleobases (ChemBioChem 18/2020)

Front Cover: Spectral Unmixing‐Based Reaction Monitoring of Transformations between Nucleosides and Nucleobases (ChemBioChem 18/2020)

Transport of ribavirin in human myelogenous leukemia cell line K562.

The anticancer effect of ribavirin, a purine nucleoside analogue, has been studied using cultured cancer cells such as the human myelogenous leukemia cell line K562. In order to exert its pharmacological effect, ribavirin has to enter cancer cells. However, there is little information concerning the transport mechanism of ribavirin into K562 cells. In this study, therefore, we examined the uptake mechanism of ribavirin in K562 cells. The uptake of ribavirin in K562 cells was time- and temperature-dependent, and was saturable with a Km value of 1.5 mM. Ribavirin uptake was inhibited by nucleosides such as adenosine and uridine, and by inhibitors of equilibrative nucleoside transporter 1 (ENT1) such as S-(4-nitrobenzyl)-6-thioinosine and dipyridamole in a concentration-dependent manner. In addition, the expression of ENT1 mRNA in K562 cells was confirmed by real-time PCR. On the other hand, Na+-dependence of ribavirin uptake was not observed, suggesting the involvement of ENT1, but not Na+-dependent concentrative nucleoside transporters, in ribavirin uptake in K562 cells. Treatment of K562 cells with sodium butyrate induced erythroid differentiation, but ribavirin uptake activity and sensitivity of the uptake to various inhibitors were not different between native and differentiated K562 cells. These results suggest that ribavirin uptake into K562 cells is mainly mediated by ENT1, which may have a pivotal role in anticancer effect of ribavirin.

Liquid chromatography high-resolution mass spectrometry analysis, phytochemical and biological study of two aizoaceae plants: A new kaempferol derivative from Trianthema portulacastrum L.

Background: Natural remedies used for the treatment of liver diseases have a major concernworldwide. Objectives: Evaluation of the cytotoxic potential of successive fractions of two Aizoaceae plants; Trianthema portulacastrum L. and Aizoon canariense L. against human hepatocellular carcinoma (HepG2) cell lines. Moreover, metabolomic profiling of the successive fractions of both plants was carried out. Materials and Methods: Cytotoxic activity of successive fractions of the two plants against hepatocellular carcinoma (HCC) HepG2 cell lines were evaluated using viability assay, whereas metabolomic profiling was carried out using Liquid Chromatography High-Resolution ElectroSpray Ionization Mass Spectrometry (LC-HR-ESI-MS). Results: Significant cytotoxic activity of the n-hexane and n-butanol extracts of A. canariense (24.7 ± 3.5 and 55.3 ± 4.9 μg/mL, respectively) is recorded. On the other hand, metabolomic profiling of both plants resulted in dereplication of 27 metabolites belonging to different chemical classes; for example, sterols, flavonoids, diterpenes, triterpenes, tetraterpenes, alkaloids, lignans, hydrocarbons, and nucleosides. Phytochemical study of the biologically active fractions resulted in the isolation of one new compound; kaempferol-3-O-(2''-O-β-D-glucopyranosyl)-6''-O-E-feruloyl-β-D-glucopyranosid (T1). Biological testing of the isolated compounds indicated significant activity of T1 against HCC (IC50 =7.19 ± 0.27 μg/mL). Conclusion: Phytochemicals isolated from T. portulacastrum L and A. canariense L. may be responsible for their cytotoxic activity against HCC HepG2 cell lines.

The proposed mechanisms of action of CBD in epilepsy.

Highly purified cannabidiol (CBD) (approved as Epidiolex® in the United States and as EPIDYOLEX from the EU agency) has demonstrated efficacy with an acceptable safety profile in patients with Lennox-Gastaut or Dravet syndrome in four randomized controlled trials. While the mechanism of action of CBD underlying the reduction of seizures in humans is unknown, CBD possesses affinity for multiple targets, across a range of target classes, resulting in functional modulation of neuronal excitability, relevant to the pathophysiology of many disease types, including epilepsy. Here we present the pharmacological data supporting the role of three such targets, namely Transient receptor potential vanilloid-1 (TRPV1), the orphan G protein-coupled receptor-55 (GPR55) and the equilibrative nucleoside transporter 1 (ENT-1).

Bridged Nucleosides as Building Blocks of Oligonucleotides: Synthesis and Properties

Bridged Nucleosides as Building Blocks of Oligonucleotides: Synthesis and Properties

Updates on human equilibrative nucleoside transporter 1 in neoplastic diseases

The human equilibrative nucleoside transporter 1(hENT1)is a multi-integrated membrane protein that mediates the transport of nucleosides, nucleobases and nucleoside analogs.It is mainly distributed on the cell membrane in humans.hENT1 maintains the homeostasis of cells and the intracellular concentration of nucleoside drugs through facilitating diffusion, thereby affecting DNA and RNA synthesis, cell signaling, metabolic regulation and tumor chemotherapy.This article reviews the progress in the structure and function of hENT1, the distribution in tumor tissues, the nucleoside analogs response and the prognosis of neoplastic diseases. Key words: Human equilibrative nucleoside transporter 1; Nucleoside analogs; Neoplasm

Synthesis of Nucleoside Oligophosphates: Quick and Not Dirty

Synthesis of Nucleoside Oligophosphates: Quick and Not Dirty

Correction to "Synthesis of Modified Nucleoside Oligophosphates Simplified: Fast, Pure, and Protecting Group Free".

Correction to "Synthesis of Modified Nucleoside Oligophosphates Simplified: Fast, Pure, and Protecting Group Free".

Agroactive Nucleosides from Microorganisms

Agroactive Nucleosides from Microorganisms

A retrospective study of endoscopic ultrasonography for predicting progression of esophageal varices in patients with hepatitis B virus-related hepatocirrhosis

Objective To assess the clinical value of endoscopic ultrasonography (EUS) for predicting esophageal varices (EV) progression in patients with hepatitis B virus (HBV)-related hepatocirrhosis. Methods A retrospective cohort study was performed on 299 HBV-related hepatocirrhosis patients with light EV in Tianjin Second People′s Hospital admitted from September 2014 to September 2015. The diameter and number of peri-esophageal collateral veins (ECV) and para-ECV were measured and described by EUS. The first EUS examination time was the starting point, and the follow-up of 24 months or EV progression was the end. Risk factors of EV progression were evaluated by multivariate Cox regression model, and the predictive value of EUS for EV progression was analyzed by receiver operating characteristic (ROC) curve. Results The cumulative incidence of EV progression was 2.3% (7/299), 14.8% (44/297), 33.7% (96/285) and 40.0% (120/273) at 6 months, 12 months, 18 months and 24 months of follow-up, respectively. The results of multivariate Cox regression analysis showed that the diameter of peri-ECV (P=0.011 2, HR=1.323 2, 95%CI: 1.065 6-1.642 9), the number of peri-ECV (P=0.000 1, HR=1.366 6, 95%CI: 1.163 4-1.605 2) and para-ECV diameter (P=0.000 2, HR=1.364 1, 95%CI: 1.155 8-1.610 0) were risk factors for EV progression. The use of nucleoside analogues treating HBV (P=0.002 0, HR=0.496 9, 95%CI: 0.318 6-0.775 1) and non-selective β-blockers descending portal venous pressure (P=0.076 5, HR=0.573 2, 95%CI: 0.309 7-1.061 1)were the protective factors for EV progression. The results of ROC curve analysis showed that the diameter of peri-ECV[P<0.001, area under the curve (AUC)=0.850, 95%CI: 0.804-0.895], the number of peri-ECV (P<0.001, AUC=0.831, 95%CI: 0.784-0.878), the diameter of para-ECV (P<0.001, AUC=0.924, 95%CI: 0.895-0.954), and the number of para-ECV (P<0.001, AUC=0.761, 95%CI: 0.704-0.817) had higher predictive value for EV progression; and the optimum cut-off values of each index were 1.85 mm, 3.5, 3.35 mm, and 4.5, respectively. The accuracies of prediction for EV progression were 76.60%, 75.19%, 84.48% and 70.29%, respectively. Conclusion EUS can be used to predict EV progression in HBV-related hepatocirrhosis patients. Peri-ECV diameter>1.85 mm, number>3.5, and para-ECV diameter>3.35 mm, number>4.5 suggest a high risk of EV progression. For patients with HBV-related hepatocirrhosis complicated with mild EV, nucleoside analogues to anti-HBV and non-selective β-blockers to reduce portal hypertension can prevent EV progression. Key words: Endoscopy, digestive system; Liver cirrhosis; Esophageal varices; Endoscopic ultrasonography; Predict

The application of serum HBV RNA detection in anti-HBV treatment

The persistence of covalently closed circular DNA (cccDNA) in the nucleus of liver cells is a key factor that hinders the cure of chronic hepatitis B. However, it is difficult to eliminate cccDNA with existing anti-HBV therapy. Recent studies have found that serum HBV RNA may be a new indicator reflecting the activity of cccDNA in hepatocytes and evaluating the clinical efficacy of CHB patients. This article reviews recent advances in the properties, detection methods, and clinical significance of HBV RNA, particularly the application of antiviral therapy in CHB patients. Key words: Hepatitis B, chronic; Hepatitis B virus; RNA, viral; DNA, circular; Nucleosides; Interferon-alpha; Polyethylene glycols

Lineage Tracing: Computational Reconstruction Goes Beyond the Limit of Imaging.

Tracking the fate of individual cells and their progeny through lineage tracing has been widely used to investigate various biological processes including embryonic development, homeostatic tissue turnover, and stem cell function in regeneration and disease. Conventional lineage tracing involves the marking of cells either with dyes or nucleoside analogues or genetic marking with fluorescent and/or colorimetric protein reporters. Both are imaging-based approaches that have played a crucial role in the field of developmental biology as well as adult stem cell biology. However, imaging-based lineage tracing approaches are limited by their scalability and the lack of molecular information underlying fate transitions. Recently, computational biology approaches have been combined with diverse tracing methods to overcome these limitations and so provide high-order scalability and a wealth of molecular information. In this review, we will introduce such novel computational methods, starting from single-cell RNA sequencing-based lineage analysis to DNA barcoding or genetic scar analysis. These novel approaches are complementary to conventional imaging-based approaches and enable us to study the lineage relationships of numerous cell types during vertebrate, and in particular human, development and disease.

A Practical and Convenient Method for Utilization of the Mother Liquors Containing 1,2,3,5-Tetra-O-Acetyl-α-D-Ribofuranose

1,2,3,5-Tetra-O-acetyl-β-D-ribofuranose is an important pharmaceutical intermediate which is prepared via the cleavage of nucleosides, such as inosine,1 adenosine1 and guanosine.2 It is usually cry...