Sugar–Oligoamides: Synthesis of DNA Minor Groove Binders

Glucosyltriazole amphiphile treatment attenuates breast cancer by modulating the AMPK signaling

Breast cancer is the second most frequent cancer among women. Out of various subtypes, triple-negative breast cancers (TNBCs) account for 15% of breast cancers and exhibit more aggressive characteristics as well as a worse prognosis due to their proclivity for metastatic progression and limited therapeutic strategies. It has been demonstrated that AMP-activated protein kinase (AMPK) has context-specific protumorigenic implications in breast cancer cells. A set of glucosyltriazole amphiphiles, consisting of acetylated (9a-h) and unmodified sugar hydroxyl groups (10a-h), were synthesized and subjected to in vitro biological evaluation. Among them, 9h exhibited significant anticancer activity against MDA-MB-231, MCF-7, and 4T1 cell lines with IC50 values of 12.5, 15, and 12.55 μM, respectively. Further, compound 9h was evaluated for apoptosis and cell cycle analysis in in vitro models (using breast cancer cells) and antitumour activity in an in vivo model (orthotopic mouse model using 4T1 cells). Annexin-V assay results revealed that treatment with 9h caused 34% and 28% cell death at a concentration of 15 or 7.5 μM, respectively, while cell cycle analysis demonstrated that 9h arrested the cells at the G2/M or G1 phase in MCF-7, MDA-MB-231 and 4T1 cells, respectively. Further, in vivo, investigation showed that compound 9h exhibited equipotent as doxorubicin at 7.5 mg/kg, and superior efficacy than doxorubicin at 15 mg/kg. The mechanistic approach revealed that 9h showed potent anticancer activity in an in vivo orthotopic model (4T1 cells) partly by suppressing the AMPK activation. Therefore, modulating the AMPK activation could be a probable approach for targeting breast cancer and mitigating cancer progression.

Synthesis of N-glycosyl amides: conformational analysis and evaluation as inhibitors of β-galactosidase from E. coli

The synthesis of N-glycosyl amides typically involves the use of glycosyl amines as direct precursors, resulting in low yields due to hydrolysis and the loss of stereocontrol through anomerization processes. In this study, a sequential synthesis of N-glycosyl amides is proposed, employing glycosyl amines as intermediates obtained from glycosyl azides. Derivatives with gluco, galacto, or xylo configurations were synthesized. Hexose derivatives were obtained under stereocontrol to give only the β anomer, while the xylo derivatives provided a mixture of α and β anomers. Conformational analysis revealed that all β anomers adopted the 4C1 conformation, while α anomers were found in the 1C4 chair as the major conformer. After de-O-acetylation, the derivatives containing a galactose unit were evaluated as inhibitors of β-galactosidase from E. coli and were found to be moderate inhibitors.

A glucose-based molecular rotor inhibitor of glycogen phosphorylase as a probe of cellular enzymatic function

Molecular rotors belong to a family of fluorescent compounds characterized as molecular switches, where a fluorescence on/off signal signifies a change in the molecule’s microenvironment. Herein, the successful synthesis and...

Novel 1,2,3-triazole-tethered Pam3CAG conjugates as potential TLR-2 agonistic vaccine adjuvants

A focused library of water soluble 1,2,3-triazole tethered glycopeptide conjugates derived from variety of azido-monosaccharides and aliphatic azido-alcohols were synthesized through manipulation at the C-terminus of Pam₃CAG and screened for their potential as TLR2 agonistic adjuvants against HBsAg antigen. In vitro ligand induced TLR2 signal activation was observed with all the analogues upon treatment with HEK blue TLR2 cell lines. Conjugate derived from ribose (6e), which exhibited pronounced HBsAg specific antibody (IgG) titer also shown enhanced CD8+ population indicating superior cell mediated immunity compared to standard adjuvant Pam₃CSK₄. Further, docking studies revealed ligand induced heterodimerization between TLR1 and 2. Overall, the result indicates the usefulness of novel conjugates as potential vaccine adjuvant.

Synthesis of biurets via TMSNCO addition to 1-aminosugars: application in the de novo synthesis of dC oxidation products

The reaction between 1-aminosugars and trimethylisocyanate (TMSNCO) was optimised as a one-step synthetic strategy for the synthesis of sugar biurets. This protocol was successfully applied to a number of 1-aminosugars, which exclusively provided the corresponding biurets in 67-99% yields. The new methodology was applied in the de novo synthesis of N1-(2-deoxy-α/β-d-erythro-pentofuranosyl)biuret (dfBU) and N1-(2-deoxy-α/β-d-erythro-pentopyranosyl)biuret (dpBU), two known DNA lesions arising from the hydroxyl radical induced decomposition of 2'-deoxycytidine (dCyd).

An overview of recent advances in duplex DNA recognition by small molecules

As the carrier of genetic information, the DNA double helix interacts with many natural ligands during the cell cycle, and is amenable to such intervention in diseases such as cancer biogenesis. Proteins bind DNA in a site-specific manner, not only distinguishing between the geometry of the major and minor grooves, but also by making close contacts with individual bases within the local helix architecture. Over the last four decades, much research has been reported on the development of small non-natural ligands as therapeutics to either block, or in some cases, mimic a DNA–protein interaction of interest. This review presents the latest findings in the pursuit of novel synthetic DNA binders. This article provides recent coverage of major strategies (such as groove recognition, intercalation and cross-linking) adopted in the duplex DNA recognition by small molecules, with an emphasis on major works of the past few years.

Multicomponent Synthesis of Cyclic Depsipeptide Mimics by Ugi Reaction Including Cyclic Hemiacetals Derived from Asymmetric Organocatalysis

The synthesis of novel cyclic depsipeptide mimics by means of an organocatalytic conjugate addition, leading to chiral cyclic hemiacetals, followed by a multicomponent reaction with α-amino acids and isocyanides, is described. The initial organocatalytic step is employed for the asymmetric derivatization of α,β-unsaturated aldehydes to 4,5-disubstituted 2-hydroxytetrahydropyrans, which are next used as chiral bifunctional substrates on the Ugi five-center three-component reaction, giving rise to nine-membered-ring lactones. This sequential approach proved to be suitable for the rapid generation of molecular complexity through the combination of aliphatic, dipeptidic, glucosidic, and lipidic isocyanides with several amino acids, thus giving access to amido-, glyco-, and lipo-depsipeptide scaffolds featuring natural product-like structures.

Metal/organo relay catalysis in a one-pot synthesis of methyl 4-aminopyrrole-2-carboxylates from 5-methoxyisoxazoles and pyridinium ylides

Methyl 4-aminopyrrole-2-carboxylates were easily synthesized by the reaction of 5-methoxyisoxazoles with phenacylpyridinium salts under hybrid relay catalysis leading to 1-(5-methoxycarbonyl-1H-pyrrol-3-yl)pyridinium salts followed by a one pot Zincke cleavage.

β-Glucosidase involvement in the bioactivation of glycosyl conjugates in plants: synthesis and metabolism of four glycosidic bond conjugates in vitro and in vivo

Mobile glucose-pesticide conjugates in the phloem are often restricted by decreases in biological activity. However, plants can bioactivate endogenous glucosides, which are assumed as able to bioactivate exogenous conjugates. In this study, four glycosidic bonds (O-, S-, N-, and C-glycosidic bonds) of glucose-pesticide conjugates were designed and synthesized, and then metabolism assays were carried out in vitro and in vivo. Results showed that β-glucosidases played a role in the hydrolysis of O-glycosidic bond conjugates in Ricinus communis L. The liberated aglycons possessed insecticidal activities against Plutella xylostella L. and Spodoptera litura F. These results could help establish methods of circumventing the mutual exclusivity of phloem mobility and biological activity by hydrolyzing endogenous β-glucosidases.

Synthesis of aromatic glycoconjugates. Building blocks for the construction of combinatorial glycopeptide libraries

New aromatic glycoconjugate building blocks based on the trifunctional 3-aminomethyl-5-aminobenzoic acid backbone and sugars linked to the backbone by a malonyl moiety were prepared via peptide coupling. The orthogonally protected glycoconjugates, bearing an acetyl-protected glycoside, were converted into their corresponding acids which are suitable building blocks for combinatorial glycopeptide synthesis.

Cooperative hydrogen bonding in glyco-oligoamides: DNA minor groove binders in aqueous media

A strategy to create cooperative hydrogen-bonding centers by using strong and directional intramolecular hydrogen-bonding motifs that can survive in aqueous media is presented. In particular, glyco-oligoamides, a family of DNA minor groove binders, with cooperative and non-cooperative hydrogen-bonding donor centers in the carbohydrate residues have been designed, synthesized, and studied by means of NMR spectroscopy and molecular modeling methods. Indeed, two different sugar moieties, namely, β-D-Man-Py-γ-Py-Ind (1; Ind=indole, Man=mannose, Py=pyrrole) and β-D-Tal-Py-γ-Py-Ind (2; Tal=talose), were chosen according to our design. These sugar molecules should present one- or two-directional intramolecular hydrogen bonds. The challenge has been to study the conformation of the glyco-oligoamides at low temperature in physiological media by detecting the exchangeable protons (amide NH and OH resonances) by means of NMR spectroscopic analysis. In addition, two more glyco-oligoamides with non-cooperative hydrogen-bonding centers, that is, β-D-Glc-Py-γ-Py-Ind (3; Glc=glucose), β-D-Gal-Py-γ-Py-Ind (4; Gal=galactose), and the model compounds β-D-Man-Py-NHAc (5) and β-D-Tal-Py-NHAc (6) were synthesized and studied for comparison. We have demonstrated the existence of directional intramolecular hydrogen bonds in 1 and 2 in aqueous media. The unexpected differences in terms of stabilization of the intramolecular hydrogen bonds in 1 and 2 relative to 5 and 6 promoted us to evaluate the influence of CH-π interactions on the establishment of intramolecular hydrogen bonds by using computational methods. Initial binding studies of 1 and 2 with calf-thymus DNA and poly(dA-dT)2 by NMR spectroscopic analysis and molecular dynamics simulations were also carried out. Both new sugar-oligoamides are bound in the minor groove of DNA, thus keeping a stable hairpin structure, as in the free state, in which both intramolecular hydrogen-bonding and CH-π interactions are present.