Tuning uracil derivatives for the AIE-based detection of pyrene at a nano-molar level: single-crystal X-ray structure and DFT support

Single crystal X-ray structurally characterized azo-uracil derivative (L) is explored for the selective detection of pyrene via aggregation-induced emission (AIE) with 99-fold fluorescence enhancement.

Synthesis and Biological Evaluation of Structurally Varied 5′-/6′-Isonucleosides and Theobromine-Containing N-Isonucleosidyl Derivatives

Isonucleosides are rather stable regioisomeric analogs of nucleosides with broad therapeutic potential. We have previously demonstrated the ability of 5′ and 6′-isonucleosides to inhibit the activity of acetylcholinesterase, a major target for Alzheimer’s disease therapy. Continuing with our research on this topic, we report herein on the synthesis and biological evaluation of a variety of novel terminal isonucleosides and theobromine isonucleotide analogs. Xylofuranose-based purine or uracil 5′-isonucleosides and xylofuranos-5′-yl or glucos-6′-yl theobromine derivatives were accessed via Mitsunobu coupling between partially protected xylofuranose or glucofuranose derivatives with a nucleobase using conventional or microwave-assisted heating conditions. Theobromine-containing N-isonucleosidyl sulfonamide and phosphoramidate derivatives were synthesized from isonucleosidyl acetate precursors. The most active compounds in the cholinesterase inhibition assays were a glucopyranose-based theobromine isonucleosidyl acetate, acting as a dual inhibitor of acetylcholinesterase (AChE, Ki = 3.1 µM) and butyrylcholinesterase (BChE, Ki = 5.4 µM), and a 2-O,4-O-bis-xylofuranos-5′-yl uracil derivative, which displayed moderate inhibition of AChE (Ki = 17.5 µM). Docking studies revealed that the active molecules are positioned at the gorge entrance and at the active site of AChE. None of the compounds revealed cytoxic activity to cancer cells as well as to non-malignant mouse fibroblasts.

Nitroxide-labeled pyrimidines for non-covalent spin-labeling of abasic sites in DNA and RNA duplexes

Of ten new pyrimidine-derived nitroxide spin labels, an N1-ethylamino triazole-linked uracil derivative binds fully to both DNA and RNA duplexes containing an abasic site, as determined by CW-EPR.