We report findings on a novel family of nucleotide analogues with selective inhibitory activity against DNA polymerase theta (Polθ), a key enzyme in the theta-mediated end joining pathway and a critical player in synthetic lethality-based cancer therapies. Polθ's intrinsically low fidelity, which contributes to genomic instability in homologous recombination-deficient tumors, was probed for selective targeting by these analogues. The newly identified compounds feature an all-carbon stereogenic quaternary center at either the C3' or C2' position of the furanoside ring, a structural modification that has already demonstrated potential in antiviral, anticancer, and cardioprotective applications. Biochemical assays suggest these analogues exploit Polθ's unique active site architecture, offering a possible direction for overcoming PARP inhibitor resistance and enhancing personalized cancer treatment strategies.

Heart failure (HF) is a significant global health burden with a high mortality rate and no curative or preventative treatment. Many factors can contribute to HF development, including hemodynamic factors and chemotherapy-induced cardiotoxicity. Loss of cardiomyocytes triggers cardiac remodeling and HF, suggesting that strategies aimed at preserving cardiomyocyte survival could provide therapeutic benefits. Here, we describe the biological activity of an adenosine-like nucleoside analogue bearing an all-carbon stereogenic quaternary center that induces a conformational bias to enhance both activity and selectivity. The lead compound, LCB-2122, prevents cardiomyocyte death both in vitro and in vivo in an animal model of acute chemotherapy-induced HF. This protective effect against chemotherapy-induced cardiomyocyte loss is linked to AMPK activation and is abrogated by siRNA-mediated reduction of AMPK expression. The results suggest that targeting cardiomyocyte survival with conformationally biased nucleoside analogues may offer a promising avenue for preventing cardiac dysfunction and the progression of HF.

A novel nucleoside analogue, LCB-2151, has been developed to induce cell death in KRAS-mutated pancreatic human cancer cell lines, which exhibit partial resistance to gemcitabine, a widely used anticancer drug. LCB-2151 disrupts the two primary sources of ATP production, namely, glycolysis and mitochondrial oxidative phosphorylation, reducing the bioenergetic capacity of these cells and inducing the formation of reactive oxygen species. Metabolomics and mitochondrial respiration analyses reveal that LCB-2151 inhibits key enzymes in glycolysis, the TCA cycle, and fatty acid β-oxidation. These findings highlight a coordinated mechanism driving bioenergetic disruption and cell death.

The design of novel 4′-thionucleoside analogues bearing a C2′ stereogenic all-carbon quaternary center is described. The synthesis involves a highly diastereoselective Mukaiyama aldol reaction, and a diastereoselective radical-based vinyl group transfer to generate the all-carbon stereogenic C2′ center, along with different approaches to control the selectivity of the N-glycosidic bond. Intramolecular SN2-like cyclization of a mixture of acyclic thioaminals provided analogues with a pyrimidine nucleobase. A kinetic bias favoring cyclization of the 1′,2′-anti thioaminal furnished the desired β-D-4′-thionucleoside analogue in a 7:1 ratio. DFT calculations suggest that this kinetic resolution originates from additional steric clash in the SN2-like transition state for 1′,4′-trans isomers, causing a significant decrease in their reaction rate relative to 1′,4′-cis counterparts. N-glycosylation of cyclic glycosyl donors with a purine nucleobase enabled the formation of novel 2-chloroadenine 4′-thionucleoside analogues. These proprietary molecules and other derivatives are currently being evaluated both in vitro and in vivo to establish their biological profiles.

Inflammatory disorders, such as sepsis, pancreatitis, and severe COVID-19, often cause immune dysfunction and high mortality. These conditions trigger excessive immune cell influx, leading to cytokine storms, organ damage, and compensatory immune suppression that results in immunoparalysis, organ dysfunction, and reinfection. Controlled and reversible immunosuppression limiting immune cell recruitment to inflammation sites could reduce hyperinflammation and prevent immune exhaustion. PSGL-1 on leukocytes binds to vascular P- and E-selectins via its sialyl Lewis(x) pharmacophore, triggering key features of systemic inflammatory response syndrome and sepsis. We report the discovery of two immunomodulators, sialyl Lewis(x) glycomimetics (12 and 13), with a tetrazole carboxyl bioisostere of 3a, which binds P- and E-selectin and blocks their interaction with PSGL-1. In an in vivo hyperinflammation model, they reduced immune cell recruitment, evidenced by decreased neutrophils, CD11b+, monocytes/macrophages, and PSGL-1-positive cells at various time points. These glycomimetics may be promising leads for managing the systemic inflammatory response syndrome.

E- and P-selectins are adhesion proteins implicated inimmune cellrecruitment at sites of infection, making them important drug targetsfor diseases involving excessive and uncontrolled inflammation. Inthis study, we developed an efficient strategy to synthesize bicyclicgalactopyranosides through a key stereoselective equatorial C4-propiolateaddition and TMSCN axial C-glycosidation. The nitrile group can thenbe converted to the carboxyl and different bioisosteres at a latestage in the synthesis, allowing for various derivatizations to potentiallyenhance biological activity. The sialyl Lewis(X) glycomimeticfeaturing this rigidified bicyclic galactopyranoside moiety preventsneutrophil adhesion to endothelial cells in vitro by binding to both E- and P-selectins. We show here that the axialcarboxyl analogue blocks immune cell recruitment in vivo, demonstrating its potential as an immunomodulator.

Neutrophil binding to vascular P- and E-selectin is the rate-limiting step in the recruitment of immune cells to sites of inflammation. Many diseases, including sickle cell anemia, post-myocardial infarction reperfusion injury, and acute respiratory distress syndrome are characterized by dysregulated inflammation. We have recently reported sialyl Lewisx analogues as potent antagonists of P- and E-selectin and demonstrated their in vivo immunosuppressive activity. A key component of these molecules is a tartrate diester that serves as an acyclic tether to orient the fucoside and the galactoside moiety in the required gauche conformation for optimal binding. The next stage of our study involved attaching an extended carbon chain onto one of the esters. This chain could be utilized to tether other pharmacophores, lipids, and contrast agents in the context of enhancing pharmacological applications through the sialyl Lewisx / receptor-mediated mechanism. Herein, we report our preliminary studies to generate a small library of tartrate based sialyl Lewisx analogues bearing extended carbon chains. Anionic charged chemical entities are attached to take advantage of proximal charged amino acids in the carbohydrate recognition domain of the selectin receptors. Starting with a common azido intermediate, synthesized using copper-catalyzed Huisgen 1,3-dipolar cycloadditions, these molecules demonstrate E- and P-selectin binding properties.

The design of novel nucleoside triphosphate (NTP) analogues bearing an all-carbon quaternary center at C2′ or C3′ is described. The construction of this all-carbon stereogenic center involves the use of an intramoleculer photoredox-catalyzed reaction. The nucleoside analogues (NA) hydroxyl functional group at C2′ was generated by diastereoselective epoxidation. In addition, highly enantioselective and diastereoselective Mukaiyama aldol reactions, diastereoselective N-glycosylations and regioselective triphosphorylation reactions were employed to synthesize the novel NTPs. Two of these compounds are inhibitors of the RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2, the causal virus of COVID-19.

The progress towards the development of a nucleoside analogue with inhibitory properties against SETDB1, a histone methyltransferase (HMT), is described. Based on the structure of the natural cofactor S-adenosyl-L-methionine (SAM), novel fluorinated nucleoside analogues were synthesized. Two of these compounds bearing a C2′-F and C5′-primary amine moiety showed moderate inhibition of SETDB1, a lysine HMT for which there is only one reported inhibitor.

An acyclic approach to synthesize thiofuranoside N-glycosides bearing an adenine nucleobase is presented herein. This approach provides a significant improvement in terms of regio- and diastereoselectivity compared with the current paradigms used for their formation. Activation of acyclic dithioacetal substrates bearing either a C2′-alkoxy or fluoro group and coupling with purine nucleobases selectively generates 1′,2′-syn thioaminals. The regiochemistry of the nucleobase coupling (N7 or N9) can also be controlled by using either silylated or unsilylated purines. A subsequent SN2-like cyclization of these 1′,2′-syn acyclic thioaminals results in the desired 1′,2′-cis thionucleoside analogues.

A synthetic strategy to access a novel family of nucleoside analogues bearing a C3'-nitrile substituted all-carbon quaternary center is presented herein. These purine bearing scaffolds were tested in two pancreatic cancer cell lines harboring either wild-type (BxPC3) or G12V KRAS (Capan2) mutations. A promising compound was shown to have significantly greater efficacy in the Capan2 cell line as compared to Gemcitabine, the clinical gold standard used to treat pancreatic cancer.

The synthesis of novel nucleoside analogues bearing a C3' all-carbon quaternary center and a C2'-hydroxy substituent is described. The all-carbon stereogenic center was generated through an intramolecular 7-endo attack of a silyl-tethered allyl moiety on a tertiary radical using photoredox catalysis. Subsequent allylic oxidation and diastereoselective hydride reductions provided the hydroxy substituent at C2', which then controls the stereoselective introduction of pyrimidine nucleobases on the corresponding furanose scaffold. Density functional theory (DFT) calculations provided insights into the origin of the high syn diastereoselectivity resulting from the radical cyclization. This original methodology grants access to a wide range of 1',2'-cis and 1',2'-trans arabino- and ribo-like analogues bearing an all-carbon quaternary center at C3'. These molecules are currently being tested for their antiviral and anticancer properties.

Reported herein is the synthesis of sialyl LewisX analogues bearing a trans-bicyclo[4.4.0] dioxadecane-modified 3- O,4- C-fused galactopyranoside scaffold that locks the carboxylate pharmacophore in either the axial or equatorial position. This novel series of bicyclic galactopyranosides are prepared through a stereocontrolled intramolecular cyclization reaction that has been evaluated both experimentally and by density functional theory calculations. The cyclization precursors are obtained from β-d-galactose pentaacetate in a nine-step sequence featuring a highly diastereoselective equatorial alkynylation and Cu(I) catalyzed formation of the acetylenic α-ketoester moiety. Preliminary biological evaluations indicate improved activity as P-selectin antagonists for the axially configured analogues as compared to their equatorial counterparts.

The design of novel xylo-like nucleoside analogues bearing a C3' all-carbon quaternary center and a C2'-hydroxy substituent is described. Synthesis of this scaffold makes use of highly diastereoselective transformations on acyclic substrates. Central to the approach is formation of a 2,4-syn cyanohydrin from cyanide addition onto an aldehyde through a proposed seven-membered ring chelate using a bidentate Lewis acid. In addition, a highly diastereoselective Mukaiyama aldol reaction, an intramolecular radical atom cyclization, and thioaminal formation are used to generate this novel molecule. A series of related nucleoside analogues are being tested as antiviral and anticancer agents. [GRAPHICS] .

The design of novel nucleoside analogues bearing a C2' all-carbon quaternary center is described. The construction of this all-carbon stereogenic center involves the use of photoredox catalysis to initiate an intramolecular attack of a silyl-tethered vinyl functionality on a tertiary radical. Density functional theory calculations were performed to explore the origin of the high syn diastereoselectivity obtained through the preferred 5-exo-trig cyclization mode. The intramolecular vinyl addition also enables the preparation of the complementary configuration of the C2' all-carbon stereocenter when performed after lactonization.

Reported herein are the first diastereoselective and Lewis acid-mediated radical reactions of N-heterocyclic carbene (NHC) boranes. We applied these reactions to the synthesis of four propionate diastereoisomers combining an aldol reaction, followed by a stereoselective radical-based reduction in which the NHC borane serves as the hydrogen donor, thus obviating the use of tin-based reagents. The 2,3-syn isomer is obtained by combining an NHC-borane and a Lewis acid (MgBr2·OEt2), while using a reverse polarity strategy provides the 2,3-anti isomer.

Nucleoside analogues bearing a fluorine in the C2'-position have been synthesized by S(N)2-like cyclizations of acyclic thioaminal precursors. This strategy provides access to two scaffolds, D-1',2'-cis-thiofuranosides and D-1',2'-trans-furanosides, which are difficult to generate using the standard approach for nucleoside synthesis. The addition of silylated nucleobases onto model C2-fluorinated dithioacetal substrates resulted in 1,2-syn diastereoselectivity, which is consistent with the C2-F and S-alkyl moiety being in close proximity. A new series of analogues bearing a C3' all-carbon quaternary center along with a C2'-F atom have also been synthesized using this approach and are being investigated as potential antimetabolites.