Discovery of novel N4-alkylcytidines as promising antimicrobial agents.

The emergence of drug-resistant strains of pathogenic microorganisms necessitates the creation of new drugs. In order to find new compounds that effectively inhibit the growth of pathogenic bacteria and fungi, we synthesized a set of N4-derivatives of cytidine, 2'-deoxycytidine and 5-metyl-2'-deoxycytidine bearing extended N4-alkyl and N4-phenylalkyl groups. The derivatives demonstrate activity against a number of Gram-positive bacteria, including Mycobacterium smegmatis (MIC = 24-200 µM) and Staphylococcus aureus (MIC = 50-200 µM), comparable with the activities of some antibiotics in medical use. The most promising compound appeared to be N4-dodecyl-5-metyl-2'-deoxycytidine 4h with activities of 24 and 48 µM against M. smegmatis and S. aureus, respectively, and high inhibitory activity of 0.5 mM against filamentous fungi that can, among other things, damage works of art, such as tempera painting. Noteworthy, some of other synthesized compounds are active against fungal growth with the inhibitory concentration in the range of 0.5-3 mM.

"Mirror" Method to Estimate Mutagenic Activity of DNA Lesions.

We propose an improved method for detecting mutations that arise in DNA due to misincorporations of deoxyadenosine-5'-monophosphate (dAMP) opposite 7,8-dihydro-8-oxoguanine (8-oxoG). The method is based on the synthesis of complementary chains ("mirror" products) using a template containing 8-oxoG. The misincorporation of dAMP in the "mirror" product forms EcoRI sites. The restriction analysis of double-stranded DNAs obtained by PCR of "mirror" product allows quantification of the mutagenesis frequency. In addition, single-strand conformational polymorphism (SSCP) analysis of the single-stranded "mirror" products shows that different DNA polymerases only incorporate dA or dC opposite 8-oxoG. The proposed approach used in developing this technique can be applied in the study of other lesions as well, both single and clustered.