Benzimidazole as deazapurine analogue for microbial transglycosylation

Novel fleximer pyrazole-containing adenosine analogues: chemical, enzymatic and highly efficient biotechnological synthesis

Nucleoside analogues have long served as key chemotherapeutic drugs for the treatment of viral infections and cancers. Problems associated with the development of drug resistance have led to a search for the design of nucleosides capable of bypassing point mutations in the target enzyme's binding site. As a possible answer to this, the Seley-Radtke group developed a flexible nucleoside scaffold (fleximers), where the heterocyclic purine base is split into its two components, i.e. pyrimidine and imidazole. Herein, we present a series of new pyrazole-containing flex-bases and the corresponding fleximer analogues of 8-aza-7-deaza nucleosides. Subsequent studies found that pyrazole-containing flex-bases are substrates of purine nucleoside phosphorylase (PNP). We have compared the chemical synthesis of fleximers and enzymatic approaches with both isolated enzymes and the use of E. coli cells overproducing PNP. The latter provided stereochemically pure pyrazole-containing β-d-ribo- and β-d-2'-deoxyribo-fleximers and are beneficial in terms of environmental issues, are more economical, and streamline the steps required from a chemical approach. The reaction is carried out in water, avoiding hazardous chemicals, and the products are isolated by ion-exchange chromatography using water/ethanol mixtures for elution. Moreover, the target nucleosides were obtained on a multi-milligram scale with >97-99% purity, and the reactions can be easily scaled up.

Research in Benzimidazole Compounds as Antibacterial Agents

Benzimidazole compounds are known to possess varied biological activities and so far various types of benzimidazole drugs have extensively been used in clinic. Benzimidazole compounds as a antibacterial agents has been a quite rapidly developing and is gradually becoming a relatively independent scientific area. In this paper we presented the recent advances of benzimidazole compounds as antibacterial agents. The perspective of the foreseeable future and potential application of benzimidazole as antibacterial agents are also presented.

Enzymatic synthesis of nucleoside analogues using immobilized 2'-deoxyribosyltransferase from Lactobacillus reuteri

Covalent attachment of recombinant Lactobacillus reuteri 2'-deoxyribosyltransferase to Sepabeads EC-EP303 leads to the immobilized biocatalyst SLrNDT4, which displayed an enzymatic activity of 65.4 IU/g of wet biocatalyst in 2'-deoxyadenosine synthesis from 2'-deoxyuridine and adenine at 40°C and pH 6.5. Response surface methodology was employed for the optimization of SLrNDT4 activity. Optimal conditions for SLrNDT4 highest activity were observed at 40°C and pH 6.5. Immobilized biocatalyst retained 50% of its maximal activity after 17.9 h at 60°C, whereas 96% activity was observed after storage at 40°C for 110 h. This novel immobilized biocatalyst has been successfully employed in the enzymatic synthesis of different natural and therapeutic nucleosides effective against cancer and viral diseases. Among these last products, enzymatic synthesis of therapeutic nucleosides such as 5-ethyl-2'-deoxyuridine and 5-trifluorothymidine has been carried out for the first time. Importantly for its potential application, SLrNDT4 could be recycled for 26 consecutive batch reactions in the synthesis of 2,6-diaminopurine-2'-deoxyriboside with negligible loss of catalytic activity.

1-Isopropyl-4-nitro-6-meth-oxy-1H-benzimidazole

There are two independent mol­ecules in the asymmetric unit of the title compound, C₁₁H₁₃N₃O₃. The inter­planar angles for the two rings of the benzimidazole ring system is 2.21 (12)° in one mol­ecule and 0.72 (12)° in the other. The nitro group is twisted in the same direction relative to the least-squares plane through its attached benzene ring in both mol­ecules, with inter­planar angles of 15.22 (9) and 18.02 (8)°. In the crystal structure, mol­ecules are stacked along the a axis through π–π inter­actions (centroid–centroid distance 4.1954 Å). C—H⋯O hydrogen bonds are also present.

Microbial Hydrolysis of Acetylated Nucleosides

Enzymatic hydrolysis of acetylated nucleosides using microbial whole cells has been carried out for the first time. Unlike Candida antarctica B lipase-catalysed alcoholysis, none of the tested microorganisms displayed a common deacetylation profile. Depending on the substrate and the biocatalyst used, 5'-selective deprotection or mixtures of mono O-acetylated products were obtained.