Syntheses of 5′-amino-2′,5′-dideoxy-2′,2′-difluorocytidine derivatives as novel anticancer nucleoside analogs

Poly(anhydride-ester) gemcitabine: Synthesis and particle engineering of a high payload hydrolysable polymeric drug for cancer therapy

Gemcitabine (GMT) is a nucleoside analog used in the treatment of a variety of solid tumors. GMT was chemically modified with a hydrolysable linker, and subsequently incorporated into a poly(anhydride-ester) backbone via melt-polymerization, with the active antimetabolite GMT, thus, becoming the repeat unit that makes up this new material, a biodegradable polymer. Characterization of the structure of polymeric GMT (polyGMT) revealed the incorporation of an average 26 molecules of GMT per polymer chain, which corresponds to a drug loading of 58%w/w. The glass transition temperature of the formed polyGMT was determined to be 123 °C. PolyGMT was engineered into nanoparticles (NPs) using a dialysis-based method, with a resulting geometric diameter of 206 ± 38 nm. The particles are easily dispersible and stable in aqueous-based media, with a hydrodynamic diameter of 229 ± 28 nm. The prepared hydrolysable polyGMT NPs demonstrate ultra-long release profile due to the hydrophobic nature of the linker, and as per characteristic erosion behavior of polymers with anhydride-ester bonds. Accelerated in vitro release studies demonstrate the recovery of free GMT upon hydrolysis, with biological activity as assessed by cytotoxicity assays performed in adenocarcinoma human alveolar basal epithelial (A549) and highly metastatic murine osteosarcoma (K7M2) cells lines. The characteristics of polyGMT, including its thermal properties and built in hydrolysable structure, are thus conducive for use in the preparation of drug delivery systems. Engineered structures prepared with polyGMT can maintain their morphology at ambient and physiologically relevant conditions, and free GMT is recovered as the anhydride and ester bonds are hydrolyzed. This work is innovative as for the first time we demonstrate the ability to polymerize GMT in a hydrolysable polymer structure, and engineer NPs of this polymeric chemotherapy. The synthetic strategy allows for tuning of the polymer hydrophobicity and thus potentialize its behavior, including degradation profile, by varying the linker chemistry. Such controlled release hydrolysable polymers with very high drug loading and controlled erosion profiles are relevant as they may offer new opportunities in drug delivery applications for the treatment of malignant neoplasms.

Novel triazole nucleoside analogues promote anticancer activity via both apoptosis and autophagy

Novel triazole nucleosides developed by the strategy of “terminal N,N-dimethylation” displayed anticancer activity mediated via apoptosis and autophagy.

Synthesis and in vitro anticancer activity of new gemcitabine-nucleoside analogue dimers containing methyltriazole or ester-methyltriazole linker

Two series of novel gemcitabine-nucleoside analogue dimers were synthesized using the 'click' chemistry approach. In the first series of dimers (21-30), the nucleoside units were connected with a stable methyltriazole 4N-3'(or 5')C linker whereas in the second series (31-40) with a cleavable ester-methyltriazole 4N-3'(or 5')C linker. Dimers 21-40 were evaluated for their cytotoxic activity in five human cancer cell lines such as cervical (HeLa), nasopharyngeal (KB), lung (A549), brain (U87), liver (HepG2) and normal dermal fibroblast cell line (HDF) using the sulforhodamine B (SRB) assay. Compound 29 comprising two gemcitabine (dFdC) units exhibited the highest activity among dimers 21-30. The activity of compound 29 was higher than that of dFdC in all the studied cancer cell lines. A similar order of activity was observed for compounds 25, 28, and 30. The best activity among all the dimers synthesized was displayed by compound 39, comprising two gemcitabine units with a cleavable linker. The activity of compound 39 was 5 to 9 times higher than that of dFdC, depending on the cell line. In addition, marked cytotoxic activity was shown by compounds 31, 36, 38, and 40.

Diastereoselective Flexible Synthesis of Carbocyclic C-Nucleosides

Carbocyclic C-nucleosides are quite rare. Our route enables flexible preparation of three classes of these nucleoside analogs from common precursors-properly substituted cyclopentanones, which can be prepared racemic (in six steps) or optically pure (in ten steps) from inexpensive norbornadiene. The methodology allows flexible manipulation of individual positions around the cyclopentane ring, namely highly diastereoselective installation of carbo- and heterocyclic substituents at position 1', orthogonal functionalization of position 5', and efficient inversion of stereochemistry at position 2'. Newly prepared carbocyclic C-analog of tubercidine, profiled in MCF7 (breast cancer) and HFF1 (human foreskin fibroblasts) cell cultures, is less potent than tubercidine itself, but more selectively toxic toward the tumorigenic cells.

The identification of novel 5'-amino gemcitabine analogs as potent RRM1 inhibitors

The ribonucleotide reductase (RNR) enzyme is a heteromer of RRM1 and RRM2 subunits. The active enzyme catalyzes de novo reduction of ribonucleotides to generate deoxyribonucleotides (dNTPs), which are required for DNA replication and DNA repair processes. Complexity in the generation of physiologically relevant, active RRM1/RRM2 heterodimers was perceived as limiting to the identification of selective RRM1 inhibitors by high-throughput screening of compound libraries and led us to seek alternative methods to identify lead series. In short, we found that gemcitabine, as its diphosphate metabolite, represents one of the few described active site inhibitors of RRM1. We herein describe the identification of novel 5'-amino gemcitabine analogs as potent RRM1 inhibitors through in-cell phenotypic screening.