A series of new 3′-deoxyribosides of substituted benzimidazoles was obtained by the chemo-enzymatic method using genetically engineered E. coli purine nucleoside phosphorylase (PNP). In the case of asymmetrically substituted benzimidazole derivatives, a mixture of N1- and N3-regioisomers was formed (confirmed by NMR). The antiviral activity of the obtained compounds against herpes simplex virus 1 of reference strain L2 and a strain deeply resistant to acyclovir in Vero E6 cell culture was studied. 4,6-Difluoro-1-(β-D-3′-deoxyribofuranosyl)benzimidazole (IC₅₀ = 250.92 µM, SI = 12.00) and 4,5,6-trifluoro-1-(β-D-3′-deoxyribofuranosyl)benzimidazole (IC₅₀ = 249.96 µM, SI = 16.00) showed significant selective activity against both viral models in comparison to ribavirin (IC₅₀ = 511.88 µM, SI > 8.00).

Objective: The aim of this study was to develop an efficient method for the preparation of 2-fluorocordycepin and to evaluate its anticancer activity in vitro. Methods: An approach to chemical synthesis of 2-fluorocordycepin was developed. The conditions of chemoenzymatic synthesis of this compound were optimized. Results and Discussion: 2-Fluorocordycepin was prepared chemically using α-acetoxyisobutyryl bromide in three steps with 34% yield and by enzymatic method using E. coli purine nucleoside phosphorylase and 1-alpha phosphate of 3-deoxyribose with 66% yield. The latter compound was synthesized in eight steps: the protected isopropylidene derivative of 3-deoxyribose was obtained in four steps, followed by an attempt at direct “one pot” phosphorylation. Conclusions: Two methods of 2-fluorocordycepin preparation were proposed and implemented: chemical synthesis from 2-fluoradenosine and chemoenzymatic synthesis, including preparation of 3-deoxyerythropentofuranoso-1-phosphate, followed by transglycosylation using E. coli purine nucleoside phosphorylase. The cytotoxic activity of 2-fluorocordycepin in vitro was evaluated. It was shown that 2-fluorocordycepin exhibits antimetabolic effect against a number of cancer cell lines (Jurkat, Raji, MCF-7, THP-1, U937, A549, LS174T), which allows us to consider this compound as a promising candidate for the development of anticancer drugs.

The investigation of the structure–function relationship in hypoxanthine-guanine phosphoribosyltransferases (HGPRT) is a direction that is relevant for the development of drugs and approaches of enzymatic synthesis of modified nucleosides and nucleotides. This research paper is dedicated to the investigation of binding of sulphonate molecules, such as HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) in the active sites of HGPRT and similar proteins. We report the crystal structure of HGPRT from Escherichia coli (EcoHGPRT) in a complex with HEPES. In the obtained X-ray structure, a HEPES molecule binds to the active site in a position that mimics one of the HGPRT substrates, namely phosphoribosylpyrophosphate (PRPP). Enzymological study has shown that HEPES is an inhibitor of EcoHGPRT, along with two structurally similar molecules, namely MES and PIPES. Comparison of the observed EcoHGPRT/HEPES complex to other reported structures in the context of inhibition study results provides an opportunity to explore the variety of binding modes of HEPES and similar molecules and to discuss the structure–function relationship in this enzyme and similar proteins.

Compounds containing benzimidazole fragment exhibit pronounced antiviral, antispasmodic, neuroleptic, and antihistamine activity. The biological activity profileof benzimidazole nucleosides can be changed by introducing a substituent into the benzimidazole ring and/or carbohydrate residue. A series of new modified substituted benzimidazole nucleosides (3'd-Rib-B m) has been prepared by enzymatic method with yields from 8 to 72% and with purity morethan 95%. 3'-Deoxyinosine (3'd-Ino) and substituted benzimidazoles (B m) have been used as substrates in the transglycosylation reaction in the presence of recombinant purine nucleoside phosphorylase (PNP). At the first step, each reaction was optimized for substrate ratio and amount of PNP. Conditions: 50 o С, 2 mM potassium-phosphate buffer, pH 7.0. The next step was preparative synthesis followed by isolation of enzymatic reaction products. Thestructures of 3'd-Rib-B m were confirmed by NMR and mass-spectrometry. In the case of asymmetrically substituted benzimidazoles N1 and N3 regio-isomers were formed.