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An amphiphilic derivative of guanosine, carrying a myristoyl group at the 5′-position and two methoxy(triethylene glycol) appendages at the 2′ and 3′-positions ( 1 ), endowed with high ionophoric activity, has been here studied in its interaction mode with a model lipid membrane along with its 5′-spin-labelled analogue 2 , bearing the 5-doxyl-stearic in lieu of the myristic residue. Electron spin resonance spectra, carried out on the spin-labelled nucleolipid 2 in mixture with a DOPC/DOPG phospholipid bilayer, on one side, and on spin-labelled lipids mixed with 1 , on the other, integrated with dynamic light scattering and neutron reflectivity measurements, allowed getting an in-depth picture of the effect of the ionophores on membrane structure, relevant to clarify the ion transport mechanism through lipid bilayers. Particularly, dehydration of lipid headgroups and lowering of both the local polarity and acyl chains order across the bilayer, due to the insertion of the oligo(ethylene glycol) chains in the bilayer hydrophobic core, have been found to be the main effects of the amphiphilic guanosines interaction with the membrane. These results furnish directions to rationally implement future ionophores design. [ABSTRACT FROM AUTHOR]

To study the behavior of nucleic acid base in a nonpolar organic solvent, chloroform, we synthesized a derivative of guanosine. This derivative, guanosine-2′,3′,5′-triisobutyrate was obtained by reaction of guanosine with isobutyric anhydride, and identified by TLC, EA, IR and NMR. Hydrogen bonding specificity of this compound was revealed by IR and NMR. The molecules of guanosine-2′,3′,5′-triisobutyrate are self-associated in non-polar selvent, and hydrogen bonds by imino protons become important as the concentration increases. In the presence of a cytosine derivative, the self-association of the guanosine derivative is destroyed, resulting from interaction with cytosine derivative. [ABSTRACT FROM AUTHOR]

Abstract: Acyclovir is one of the oldest antiviral drugs, having been in use for three decades now. It is an acyclic guanosine derivative and has activity mainly against herpes virus-1 (HSV-1), herpes virus-2 (HSV-2), and varicella zoster virus (VZV). It is only weakly active against Epstein–Barr virus (EBV), cytomegalovirus (CMV), and human herpes virus-6 (HHV-6), and not used for these infections. It acts by inhibition of viral DNA synthesis. Before it can act, it has to be phosphorylated by virus-specific thymidine kinase. This step gives it a high therapeutic index, but is also a major mechanism of viral resistance. [Copyright &y& Elsevier]