Regioselective Mitsunobu Reaction of Partially Protected Uridine

<p>Mitsunobu reaction of partially acylated uridine proceeds with high regioselectivity for intramolecular S_N2 anhydro linkage closuring. Under the reaction conditions, an isomeric mixture of diacyl uridine derivatives with either free 2′- or 3′-hydroxyl group was transformed into a single cyclonucleosidic product, 2,2′-anhydro-3′,5′-di-O-acyluridine. This paper presents a possible mechanism of the reactions, the explanation of observed phenomenon based on semiempirical and density functional theory (DFT) calculations and possible utility of this synthetic pathway.</p

A fluorescence correlation spectroscopy study of ligand interaction with cytokinin-specific binding protein from mung bean

Abstract Cytokinins are essential plant hormones that regulate numerous physiological processes. Recently, a protein was identified in mung bean (Vigna radiata) and characterized as a cytokinin-specific binding protein (VrCSBP). Fluorescence correlation spectroscopy was used to investigate the interaction between VrCSBP and its ligands. The synthetic cytokinin, N-phenyl-N9-(4-pyridyl) urea, was labeled with two fluorophores, 7-nitro-2,1,3-benzoxadiazole and rhodamine B. Protein-ligand binding was analyzed in an equilibrium saturation binding experiment and confirmed by the competition assay. Surprisingly, it was found that VrCSBP binds not only to cytokinins, but also to gibberellins. In addition, in the presence of natural cytokinins and gibberellins, two populations of VrCSBP that differ in their diffusion coefficients were detected. The diffusion coefficients of these two populations could be related to mono-and dimeric states, which suggests a new mode of operation in ligand binding by VrCSBP, in which dimerization induced by natural ligands enhances the ligand binding capacity of the protein

Searching for anti-glioma activity. Ribonucleoside analogues with modifications in nucleobase and sugar moieties

Several ribonucleoside analogues with modifications in the nucleobase and sugar moiety have been screened for anti-glioma activity in the T98G glioma cell line using cervical (HeLa) cell line as reference human malignant cells, and lung fibroblast (MCR-5) cell line as non-cancerous reference cells. Among the investigated compounds, ribonucleosides containing 6-chloropurine (3), 7-guanine (5) and a pyrrolopyrimidine (18) as nucleobases, show promising anti-glioma activity with good selectivity indices, and can be considered as lead structures for further anti-cancer studies