Galli Gigerii Endothelium Corneum(GGEC), the dried gizzard membrane of Gallus gallus domesticus is a Chinese medicinal material commonly used for digestion. However, due to the particularity of texture and composition, its active ingre-dients have not been clarified so far, and there is also a lack of quality evaluation indicators. In this study, UPLC-Q-TOF-MS was used to analyze the chemical components from the water extract of GGEC, and ten nucleosides were identified for the first time. HPLC fingerprints of the water extracts of GGEC were established and the content of seven nucleosides was determined. The fingerprint similarities of 40 batches of GGEC samples ranged from 0.765 to 0.959, indicating that there were great differences among the GGEC products processed with different methods. In addition, SPSS 22.0 and SIMCA 14.1 were used for hierarchical cluster analysis(HCA) and principal component analysis(PCA) on the 19 common peaks of the HPLC fingerprints of GGEC, and the 40 batches of samples were divided into three categories: raw GGEC, fried GGEC and vinegar-processed GGEC. Eight differential components in GGEC were marked by orthogonal partial least squares discrimination analysis(OPLS-DA), two of which were adenine and thymine. The results of content determination showed that the total content of the seven nucleosides in raw GGEC, fried GGEC and vinegar-processed GGEC were 182.5-416.8, 205.3-368.7, and 194.2-283.0 μg·g~(-1), respectively. There were significant differences in the content of hypoxanthine, thymine and thymidine among the GGEC products processed with different methods(P<0.05), which were graded in the order of fried GGEC>vinegar-processed GGEC>raw GGEC. This suggested that the content of hypoxanthine, thymine and thymidine tended to increase during the frying process, and the variation range might be related to the degree of heat exposure. The established methods in this study were simple and reproducible, and could be used for qualitative and quantitative analysis of GGEC and its processed pro-ducts. This study also provided reference for the establishment of quality standards of GGEC with chemical components as control index.
Nucleosides ; Drugs, Chinese Herbal/chemistry* ; Chromatography, High Pressure Liquid ; Acetic Acid ; Thymine ; Thymidine ; Water ; Hypoxanthines

Nucleoside drugs play an essential role in treating major diseases such as tumor and viral infections, and have been widely applied in clinics. However, the effectiveness and application of nucleoside drugs are significantly limited by their intrinsic properties such as low bioavailability, lack of targeting ability, and inability to enter the cells. Nanocarriers can improve the physiological properties of nucleoside drugs by improving drug delivery efficiency and availability, maintaining drug efficacy and system stability, adjusting the binding ability of the carrier and drug molecules, as well as modifying specific molecules to achieve active targeting. Starting from the design strategy of nucleoside drug nanodelivery systems, the design and therapeutic effect of these nanomedicines are described in this review, and the future development directions of nucleoside/nucleotide-loaded nanomedicines are also discussed.
Nanomedicine ; Nucleosides/chemistry* ; Nucleotides ; Nanoparticles/chemistry* ; Drug Delivery Systems ; Drug Carriers

Online gradient extraction-high performance liquid chromatography( HPLC) method was developed for simultaneous determination of high and low polar components in Cordyceps. The sample powder of Cordyceps was uniformly mixed with diatomaceous earth,packed into extraction tank,and installed into the HPLC system. Online gradient extraction was conducted with mobile phase at 70 ℃. The separation was performed on Zorbax SB-AQ( 4. 6 mm×150 mm,5 μm) column with 0. 1% formic acid solution-methanol as the mobile phase for gradient elution at 1. 0 mL·min~(-1). The column temperature was 30 ℃,and detection wavelength was set at 260 nm. The results showed that the high and low polar components in Cordyceps could be simultaneously extracted and separated by the developed method. Meanwhile,six high polar compounds( uracil,uridine,thymine,inosine,guanosine and adenosine) and one low polar compound( ergosterol) were identified by comparison with the reference peaks. The established method is rapid,stable and environment friendly,which is helpful to improve the quality evaluation level for Cordyceps.
Chromatography, High Pressure Liquid ; Cordyceps ; chemistry ; Ergosterol ; analysis ; Nucleosides ; analysis

The aim of this paper was to compare the influence of freeze-drying and sun-drying on six main nucleosides and nucleobases of Cordyceps sinensis by HPLC. Hypoxanthine,xanthine,uridine,inosine,guanosine and adenosine were reference substances. HPLC analysis was performed on a GL Inertsustain AQ-C_(18) column( 4. 6 mm×250 mm,5 μm),with mobile phase consisting of water( A)-acetonitrile( B) at the flow rate of 1. 0 mL·min~(-1)( 0-10 min,0-1% B; 10-65 min,1%-3% B). The detection wavelength was 260 nm,the column temperature was controlled at 30 ℃,and the injection volume was 5 μL. The linear ranges of hypoxanthine,xanthine,uridine,inosine,guanosine and adenosine were 1. 025-20. 50( r = 0. 999 8),0. 545-10. 90( r = 0. 999 9),4. 051-81. 02( r = 0. 999 8),4. 044-80. 88( r= 0. 999 9),2. 075-41. 50( r= 0. 999 9),4. 032-80. 64( r = 0. 999 9) mg·L~(-1),respectively. The average recoveries of them( n = 6)were as follows: 102. 3%( RSD 2. 1%),101. 1%( RSD 2. 4%),97. 80%( RSD 1. 7%),101. 8%( RSD 1. 8%),98. 90%( RSD2. 0%) and 98. 10%( RSD 1. 4%),respectively. Each sample was processed by freeze-drying and sun-drying so as to compare the difference between the two drying methods. The contents of six index ingredients were significantly different between freeze-drying and sun-drying sample of C. sinensis. The total contents of six index ingredients in sun-drying sample were higher than that in the corresponding freeze-drying sample. This research results provide the scientific basis for the drying methods and quality evaluation of C. sinensis.
Chromatography, High Pressure Liquid ; Cordyceps ; chemistry ; Desiccation ; Freeze Drying ; Nucleosides ; analysis

A method, for determination of saponins, amino acids and nucleosides in Panacis Japonici Rhizoma of ultra fast liquid chromatography with triple quadrupole linear ion trap mass spectrometry (UFLC-QTRAP-MS/MS), was established to investigate the effect of different processing methods on the target components of Panacis Japonici Rhizoma. The chromatographic separation was performed on a XBridgeC₁₈(4.6 mm×100 mm, 3.5 μm) at 30 °C with a gradient elution of 0.1% formic acid solution-0.1% formic acid acetonitrile, and the flow rate was 0.8 mL·min⁻¹, using multiple-reaction monitoring (MRM) mode. The grey relational analysis was adopted for the analysis of different processing samples. The results showed that the thirty-three constituents were in a good linear range and the correlation coefficient was greater than 0.999 0; the precision, repeatability and stability were good; the average recovery rates were between 95.33% and 101.8%, and the relative standard deviations were less than 5%. The result of grey relational analysis showed that the complete rhizomes without peeling, which were adopted for the microwave dried method, had the best quality. The established method was accurate and reliable, which could be used to appraise the quality of Panacis Japonici Rhizoma. Our study may lay the way for the processing method of Panacis Japonici Rhizoma in optimization,normalization and standardization.
Amino Acids ; analysis ; Chromatography, High Pressure Liquid ; Chromatography, Liquid ; Nucleosides ; analysis ; Panax ; chemistry ; Phytochemicals ; analysis ; Rhizome ; chemistry ; Saponins ; analysis ; Tandem Mass Spectrometry

Polyoxin is a group of structurally-related peptidyl nucleoside antibiotics bearing C-5 modifications on the nucleoside skeleton. Although the structural diversity and bioactivity preference of polyoxin are, to some extent, affected by such modifications, the biosynthetic logic for their occurence remains obscure. Here we report the identification of PolB in polyoxin pathway as an unusual UMP C-5 methylase with thymidylate synthase activity which is responsible for the C-5 methylation of the nucleoside skeleton. To probe its molecular mechanism, we determined the crystal structures of PolB alone and in complexes with 5-Br UMP and 5-Br dUMP at 2.15 Å, 1.76 Å and 2.28 Å resolutions, respectively. Loop 1 (residues 117-131), Loop 2 (residues 192-201) and the substrate recognition peptide (residues 94-102) of PolB exhibit considerable conformational flexibility and adopt distinct structures upon binding to different substrate analogs. Consistent with the structural findings, a PolB homolog that harbors an identical function from Streptomyces viridochromogenes DSM 40736 was identified. The discovery of UMP C5-methylase opens the way to rational pathway engineering for polyoxin component optimization, and will also enrich the toolbox for natural nucleotide chemistry.
Bacterial Proteins ; chemistry ; Crystallography, X-Ray ; Methyltransferases ; chemistry ; Protein Domains ; Protein Structure, Secondary ; Pyrimidine Nucleosides ; biosynthesis ; Streptomyces ; enzymology

BACKGROUND/AIMS: Tenofovir disoproxil fumarate (TDF) plays a pivotal role in the management of drug-resistant chronic hepatitis B. However, it remains unclear whether TDF-nucleoside analogue combination therapy provides better outcomes than TDF monotherapy. This study aimed to compare the efficacy of TDF monotherapy with that of TDF-nucleoside analogue combination therapy in patients with drug-resistant chronic hepatitis B. METHODS: This retrospective cohort study included 76 patients receiving TDF-based rescue therapy for more than 12 months. Suboptimal response was defined as serum HBV-DNA level of >60 IU/mL during prior rescue therapy. Multi-drug resistance was defined as the presence of two or more drug resistance-related mutations confirmed by mutation detection assay. The relationship between baseline characteristics and virologic response (HBV DNA <20 IU/mL) at 12 months were evaluated using logistic regression analysis. RESULTS: Fifty-five patients (72.4%) were suboptimal responders to prior rescue therapy, and 26 (34.2%) had multi-drug resistance. Forty-two patients (55.3%) received combination therapy with nucleoside analogues. Virologic response at 12 months was not significantly different between the TDF monotherapy group and TDF-nucleoside analogue combination therapy group (p=0.098). The serum HBV DNA level was reduced to -4.49+/-1.67 log10 IU/mL in the TDF monotherapy group and to -3.97+/-1.69 log10 IU/mL in the TDF-nucleoside analogue combination therapy group at 12 months (p=0.18). In multivariate analysis, female sex (p=0.032), low baseline HBV-DNA level (p=0.013), and TDF monotherapy (p=0.046) were predictive factors for virologic response at 12 months. CONCLUSIONS: TDF monotherapy showed similar efficacy to that of TDF-nucleoside analogue combination therapy in patients with drug-resistant chronic hepatitis B.
Adult ; Aged ; Antiviral Agents/pharmacology/*therapeutic use ; Cohort Studies ; DNA, Viral/blood ; Drug Resistance, Viral ; Drug Therapy, Combination ; Female ; Hepatitis B virus/drug effects/genetics/isolation & purification ; Hepatitis B, Chronic/*drug therapy/virology ; Humans ; Logistic Models ; Male ; Middle Aged ; Multivariate Analysis ; Nucleosides/chemistry/therapeutic use ; Retrospective Studies ; Sex Factors ; Tenofovir/*therapeutic use ; Treatment Outcome ; Young Adult

The concentration of 5 nucleosides, uracil, uridine, guanidine, adenine and adenosine in culture of Paecilomyces hepialid was determined by the developed method of HPLC. The HPLC method was performed on a Waters SunFire C18 (4.6 mm x 250 mm, 5 μm) column with methanol-water gradient elution as the mobile phase. The detection wavelength was 260 nm and the colunmn temperature was controlled at 30 °C. The linear range was 10.00-200.00 mg · L(-1) (r = 0.9994) for uracil, 10.10-202.00 mg · L(-1) (r = 0.9992) for uridine, 10.00-200.00 mg · L(-1) (r = 0.9991) for guanidine, 10.30-206.00 mg · L(-1) (r = 0.9992) for adenine and 10.45-209.00 mg · L(-1) (r = 0.9991) for adenosine, respectively. The RSD of precision was 0.032%, 0.035%, 0.039%, 0.049%, 0.00080%, respectively. The average recoveries of uracil, guanidine, adenine, and adenosine were 97.34%, 99.10%, 101.6%, 98.61% and 100.2% with RSD of 1.3%, 2.1%, 0.96%, 0.95%, and 1.3% respectively. The method showed high sensitivity, good selectivity, linearity and repeatability, which was suitable for the content analysis of 5 nucleosides components in P. hepialid and its extracts.
Chromatography, High Pressure Liquid ; methods ; Nucleosides ; analysis ; Paecilomyces ; chemistry

This study aims to establish an HPLC method for simultaneous determination of gastrodin and eight nucleosides and nucleobases components in Gastrodia elata. The separation was carried out on an Agilent Zorbax Bonus-RP (4.6 mm x 250 mm, 5 μm) column with a methanol-(0.04% acetic acid) water solution gradient elution program at a flow rate of 1.0 mL x min(-1). The column temperature was 36 degrees C, and the detection wavelength was 254 nm. The volume of injection was 20 μL. The nine components including gastrodin, cytosine, uracil, cytosine, adenine, thymine, uridine, guanosine and adenosine were well separated. The calibration curve was well linear in the range of 2.04-262.00 mg x L(-1), 0.20-24.67 mg x L(-1), 0.18-23.75 mg x L(-1), 0.20-25.83 mg x L(-1), 0.20-26.67 mg x L(-1), 0.16-20.00 mg x L(-1), 0.22-27.71 mg x L(-1), 0.20-24.29 mg x L(-1), 0.24-30.58 mg x L(-1), respectively, and the correlation coefficient was between 0.998 9-0.999 9. The average recovery of gastrodin and eight nucleosides and nucleobases were 96.4%-99.6%, RSD less than 2.7% (n = 6). The contents of gastrodin in all the seven Tibet cultured Gastrodia elata samples were over 2 mg x g(-1). Further, all samples contain higher contents of adenosine, guanosine, uridine and cytidine compared to low contents of cytosine, uracil, adenine and thymine. The established method is accurate, reproducible and suitable for the determination of gastrodin and eight nucleosides and nucleobases comppnents in Gastrodia elata.
Benzyl Alcohols ; analysis ; Chromatography, High Pressure Liquid ; methods ; Drugs, Chinese Herbal ; analysis ; Gastrodia ; chemistry ; Glucosides ; analysis ; Nucleosides ; analysis ; Nucleotides ; analysis

Although much advancement has been achieved in the treatment of chronic hepatitis B, antiviral resistance is still a challenging issue. Previous generation antiviral agents have already developed resistance in a number of patients, and it is still being used especially in resource limited countries. Once antiviral resistance occurs, it predisposes to subsequent resistance, resulting in multidrug resistance. Therefore, prevention of initial antiviral resistance is the most important strategy, and appropriate choice and modification of therapy would be the cornerstone in avoiding treatment failures. Until now, management of antiviral resistance has been evolving from sequential therapy to combination therapy. In the era of tenofovir, the paradigm shifts again, and we have to decide when to switch and when to combine on the basis of newly emerging clinical data. We expect future eradication of chronic hepatitis B virus infection by proper prevention and optimal management of antiviral resistance.
Adenine/analogs & derivatives/pharmacology/therapeutic use ; Antiviral Agents/pharmacology/*therapeutic use ; Drug Resistance, Viral/drug effects ; Drug Therapy, Combination ; Hepatitis B virus/genetics ; Hepatitis B, Chronic/*drug therapy/prevention & control ; Humans ; Mutation ; Nucleosides/*chemistry/pharmacology/therapeutic use ; Organophosphonates/pharmacology/therapeutic use ; Virus Replication/drug effects