Anthrax is an infectious disease caused by Bacillus anthracis, a bioterrorism agent that develops resistance to clinically used antibiotics. Therefore, alternative mechanisms of action remain a challenge. Herein, we disclose deoxy glycosides responsible for specific carbohydrate-phospholipid interactions, causing phosphatidylethanolamine lamellar-to-inverted hexagonal phase transition and acting over B. anthracis and Bacillus cereus as potent and selective bactericides. Biological studies of the synthesized compound series differing in the anomeric atom, glycone configuration and deoxygenation pattern show that the latter is indeed a key modulator of efficacy and selectivity. Biomolecular simulations show no tendency to pore formation, whereas differential metabolomics and genomics rule out proteins as targets. Complete bacteria cell death in 10 min and cellular envelope disruption corroborate an effect over lipid polymorphism. Biophysical approaches show monolayer and bilayer reorganization with fast and high permeabilizing activity toward phosphatidylethanolamine membranes. Absence of bacterial resistance further supports this mechanism, triggering innovation on membrane-targeting antimicrobials.

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.

The synthesis and anticancer evaluation of new series of nucleosides constructed on 5/6-azidoglycosyl or glucuronamide moieties and containing an O- or an N-dodecyl chain, respectively, are disclosed. Based on our previous results, their structures were planned to preclude them to act via a similar metabolic pathway than that of clinically used nucleoside antimetabolites, against which cancer cells frequently acquire resistance. Xylo and gluco-configured 5/6-azido-1,2-di-O-acetyl furanosyl and pyranosyl donors containing a 3-O-dodecyl group were synthesized from diacetone-d-glucose and were subsequently coupled with silylated uracil or 2-acetamido-6-chloropurine. N-Dodecyl glucuronamide-based nucleosides were accessed from acetonide-protected glucofuranurono-6,3-lactone, which was converted in few steps into O-benzylated 1,2-di-O-acetyl furanuronamide or pyranuronamide derivatives to undergo further N-glycosylation. Both types of nucleosides demonstrated notorious antiproliferative effects in chronic myeloid leukemia (K562) and in breast cancer (MCF-7) cells. The most potent molecules were a 6ʹ-azidoglucopyranosyl N7-linked purine nucleoside and glucofuranuronamide derivatives comprising N1-linked uracil and N7-linked purine units with activities in the single-digit micromolar order of concentration against both cell lines. Their GI50 values in MCF-7 cells were similar or ca. 3-fold lower than that of the standard drug 5-fluorouracil. Cell cycle studies and immunoblotting analysis of apoptosis-associated proteins in treated K562 cells indicated that the antiproliferative effect of the most effective nucleosides is based on apoptosis induction.

The first facile and efficient route to pyranose-fused butenolides from furanose scaffolds, convenient for scaling up production, is described. Wittig olefination of 1,2-O-isopropylidene pentofuranos- or hexofuranos-3-uloses with a resonance-stabilized ylide led to the stereoselective formation of the (Z)-alpha,beta-unsaturated ester. In the presence of acid labile 5-O- or 5,6-di-O-protecting groups, acid hydrolysis of the Wittig product resulted in isomerization to the pyranose form and spontaneous lactonization to give the target molecules in good overall yield.

The synthesis of stable and potentially bioactive xylofuranosyl nucleoside analogues and potential sugar diphosphate or nucleotide mimetics comprising a 1,2,3‐triazole moiety is reported. 3′‐O‐Methyl‐branched N‐benzyltriazole isonucleosides were accessed in 5–7 steps and 42–54 % overall yields using a Cu(I)‐catalyzed cycloaddition of 3‐O‐propargyl‐1,2‐O‐isopropylidene‐α‐D‐xylofuranose with benzyl azide as key step. Related isonucleotides were obtained by 5‐O‐phosphorylation of acetonide‐protected 3‐O‐propargyl xylofuranose and further “click” cycloaddition or by Staudinger‐phosphite reaction of a 5‐azido N‐benzyltriazole isonucleoside. Hydroxy‐, amino‐ or bromomethyl triazole 5′‐isonucleosides were synthesized by thermal cycloaddition of 5‐azido 3‐O‐benzyl/dodecyl xylofuranoses with propargyl alcohol, propargylamine or propargyl bromide. Better yields (82–85 %) were obtained when using propargyl alcohol and a high 1,4‐regioselectivity was attained with propargyl bromide. Further O/N‐phosphorylation or Arbuzov reaction led to (triazolyl)methyl phosphates, phosphoramidates or phosphonates. The latter were converted into uracil nucleoside 5′‐(triazolyl)methyl phosphonates as prospective nucleoside diphosphate mimetics.