The arsenolysis reaction in the biotechnological synthesis of ribavirin. The in vitro and in vivo inhibition of influenza A virus replication with a combination of ribavirin and ozeltamivir

The biotechnological method of synthesis of the antiviral drug ribavirin based on the transglycosylation reaction was improved due to the addition of catalytic amounts of sodium arsenate. This approach allows us to hydrolyze the excess natural nucleoside guanosine, a ribose donor, and, hence, made the composition of the reaction mixture less complicated, thus facilitating the process of ribavirin isolation. It was shown that in cell cultures the combination of ribavirin and oseltamivir carboxylate inhibited the replication of the influenza A virus more effectively than each of them alone. Similar results were obtained in experiments on laboratory animals (mouse Balb/c) infected with the influenza A virus H3N2/Aichi/68 strain.     

Synthesis of Biotin-Containing Phosphoramidite Linker with Polyether Spacer Arm

A phosphoramidite linker unit, based on glycerol backbone and containing a biotin residue attached through a tetraethylene glycol spacer arm, was synthesized. DMTr-Glycidol and tetraethylene glycol were used as starting materials. After conversion of one of hydroxy groups in tetraethylene glycol into an amino group, the epoxy cycle in DMTr-glycidol was opened by this amino alcohol, resulting in the corresponding ether and some quantity of secondary amine. After attaching of biotin residue to the ether followed by phosphitylation, the desirable linker was obtained. The structure of the linker was confirmed by ¹H-¹H COSY, ¹H-¹³C HSQC, ¹H-¹³C HMBC, ¹H-¹⁵N HSQC, and ¹H-¹⁵N HMBC spectra. The resulted phosphoramidite linker unit is suitable for use in common DNA synthesizers. This approach can be used for preparation of various modifiers containing reporter groups attached to the primary amino function using conventional procedures.     

Large-Scale Solid-Phase Preparation of 3′-Unprotected Trinucleotide Phosphotriesters - Precursors for Synthesis of Trinucleotide Phosphoramidites

Abstract

The approach to large-scale solid-phase synthesis of 3′-unprotected trinucleotide phosphotriesters has been developed. The trinucleotides have been synthesized in 5 g scale by phosphotriester approach using CPG with pore size 70A. Total yield of target products was 75–90%. The molar extinctions of trinucleotides at various wavelengths were calculated; the experimental UV-spectra of trinucleotides show a good agreement with theoretical ones. The trinucleotides synthesized were used for synthesis of trinucleotide phosphoramidites - synthons for generation of DNA/peptide libraries.     

Characterization of Pectobacterium carotovorum subsp. carotovorum Bacteriophage PP16 Prospective for Biocontrol of Potato Soft Rot

Microbiology - Phages of the phytopathogenic Pectobacteriaceae species causing black leg and soft rot of potato were investigated. These phages are promising as biocontrol agents to prevent the...     

A new approach to enhance PCR specificity

A new approach to enhanced specificity and product yield of polymerase chain reaction is proposed. It is based on control of DNA polymerase activity during PCR by changing the magnesium ion concentration, which depends on the temperature of the reaction mixture. A slightly soluble magnesium salt, magnesium oxalate, whose solubility depends on temperature, was used as a source of magnesium ions. During PCR, magnesium oxalate was maintained at saturating concentration by the presence of an insoluble excess of this salt, and the concentration of magnesium ions depended on the salt solubility: binding of magnesium ions at lower temperatures and their release at higher temperatures was shown to affect the DNA polymerase activity and to favor the specific PCR amplification of the target DNA fragment.     

Large-scale solid-phase preparation of 3'-unprotected trinucleotide phosphotriesters--precursors for synthesis of trinucleotide phosphoramidites

The approach to large-scale solid-phase synthesis of 3'-unprotected trinucleotide phosphotriesters has been developed. The trinucleotides have been synthesized in 5 g scale by phosphotriester approach using CPG with pore size 70A. Total yield of target products was 75-90%. The molar extinctions of trinucleotides at various wave-lengths were calculated; the experimental UV-spectra of trinucleotides show a good agreement with theoretical ones. The trinucleotides synthesized were used for synthesis of trinucleotide phosphoramidites - synthons for generation of DNA/peptide libraries.     

Inhibition of growth of E. coli cells by anolites of sodium and potassium chloride after processing solutions in a diaphragmatic electrolyzer

The relationship between the inhibitory effect of sodium chloride and potassium anolites, obtained in a diaphragm electrolyser, and the physicochemical parameters of solutions was compared with that between the inhibitory effect and physicochemical properties of hypochlorites obtained after treating the solutions in an electrolyser having no diaphragm was compared. The biological activity of solutions containing molecular chlorine, hypochlorous acid, and hypochlorite ions was determined by their effect on the growth of E. coli cells. After a 5-min incubation of cells with each of the oxidizers, the bacterial growth stopped and was not restored during one day. The conclusion is made that the oxidizers irreversibly disturb the barrier properties of cell membranes and, in some cases, destroy cells. In model solutions, as well as in solutions treated after heating on a water bath or after the addition of sodium thiosulfate, a delay in the start of E. coli growth occurs. After the lag-phase, the repair of cells sets on, and after a day the optical density of cells increases and approaches the control.     

2,3-Dihydroxy-quinoxaline induces ATPase activity of Herpes Simplex Virus thymidine kinase

2,3-Dihydroxy-quinoxaline, a small molecule that promotes ATPase catalytic activity of Herpes Simplex Virus thymidine kinase (HSV-TK), was identified by virtual screening. This compound competitively inhibited HSV-TK catalyzed phosphorylation of acyclovir with K_i = 250 μM (95% CI: 106–405 μM) and dose-dependently increased the rate of the ATP hydrolysis with K_M = 112 μM (95% CI: 28–195 μM). The kinetic scheme consistent with this experimental data is proposed.