Deconstructing Best-in-Class Neoglycoclusters as a Tool for Dissecting Key Multivalent Processes in Glycosidase Inhibition.

Multivalency represents an appealing option to modulate selectivity in enzyme inhibition and transform moderate glycosidase inhibitors into highly potent ones. The rational design of multivalent inhibitors is however challenging because global affinity enhancement relies on several interconnected local mechanistic events, whose relative impact is unknown. So far, the largest multivalent effects ever reported for a non-polymeric glycosidase inhibitor have been obtained with cyclopeptoid-based inhibitors of Jack bean α-mannosidase (JBα-man). Here, we report a structure-activity relationship (SAR) study based on the top-down deconstruction of best-in-class multivalent inhibitors. This approach provides a valuable tool to understand the complex interdependent mechanisms underpinning the inhibitory multivalent effect. Combining SAR experiments, binding stoichiometry assessments, thermodynamic modelling and atomistic simulations allowed us to establish the significant contribution of statistical rebinding mechanisms and the importance of several key parameters, including inhitope accessibility, topological restrictions, and electrostatic interactions. Our findings indicate that strong chelate-binding, resulting from the formation of a cross-linked complex between a multivalent inhibitor and two dimeric JBα-man molecules, is not a sufficient condition to reach high levels of affinity enhancements. The deconstruction approach thus offers unique opportunities to better understand multivalent binding and provides important guidelines for the design of potent and selective multiheaded inhibitors.

sp2-Iminosugar azobenzene O-glycosides: Light-sensitive glycosidase inhibitors with unprecedented tunability and switching factors.

The conventional approach to developing light-sensitive glycosidase activity regulators, involving the combination of a glycomimetic moiety and a photoactive azobenzene module, results in conjugates with differences in glycosidase inhibitory activity between the interchangeable E and Z-isomers at the azo group that are generally below one-order of magnitude. In this study, we have exploited the chemical mimic character of sp2-iminosugars to access photoswitchable p- and o-azobenzene α-O-glycosides based on the gluco-configured representative ONJ. Notably, we achieved remarkably high switching factors for glycosidase inhibition, favoring either the E- or Z-isomer depending on the aglycone structure. Our data also indicate a correlation between the isomeric state of the azobenzene module and the selectivity towards α- and ß-glucosidase isoenzymes. The most effective derivative reached over a 103-fold higher inhibitory potency towards human ß-glucocerebrosidase in the Z as compared with the E isomeric form. This sharp contrast is compatible with ex-vivo activation and programmed self-deactivation at physiological temperatures, positioning it as a prime candidate for pharmacological chaperone therapy in Gaucher disease. Additionally, our results illustrate that chemical tailoring enables the engineering of photocommutators with the ability to toggle inhibition between α- and ß-glucosidase enzymes in a reversible manner, thus expanding the versatility and potential therapeutic applications of this approach.

Multivalent pyrrolidines acting as pharmacological chaperones against Gaucher disease.

A concise asymmetric synthesis of clickable enantiomeric pyrrolidines was achieved using Crabbé-Ma allenation. The synthesized iminosugars were grafted by copper-free strain-promoted alkyne-azide cycloaddition onto phosphorus dendrimers. The hexavalent and dodecavalent pyrrolidines were evaluated as ß-glucocerebrosidase inhibitors. The level of inhibition suggests that monofluorocyclooctatriazole group may contribute to the affinity for the protein leading to potent multivalent inhibitors. Docking studies were carried out to rationalize these results. Then, the iminosugars clusters were evaluated as pharmacological chaperones in Gaucher patients' fibroblasts. An increase in ß-glucocerebrosidase activity was observed with hexavalent and dodecavalent pyrrolidines at concentrations as low as 1 µM and 0.1 µM, respectively. These iminosugar clusters constitute the first example of multivalent pyrrolidines acting as pharmacological chaperones against Gaucher disease.

Iminosugar-Dihydroazulenes as Mutant L444P Glucocerebrosidase Enhancers.

A remarkable enhancer of human glucocerebrosidase enzyme (GCase) was identified among a set of dihydroazulene-tagged iminosugars. An unprecedented 3.9-fold increase in GCase activity was detected on fibroblasts bearing the homozygous L444P mutation, which is frequently associated with neuronopathic Gaucher forms, and which commonly results refractory to chaperone-induced refolding.

Initial report on the multiple biological and pharmacological properties of hispolon: Exploring stochastic mechanisms.

The development of natural substances derived from nature poses a significant challenge as technologies for the extraction and characterization of active principles advance. Hispolon has received a lot of attention in recent years, ascribable to its wide range of biological activities. It is a phenolic molecule that was extracted from several mushroom species such as Phellinus igniarius, Phellinus linteus, Phellinus lonicerinus, Phellinus merrillii, and Inonotus hispidus. To provide a comprehensive overview of the pharmacological activities of hispolon, this review highlights its anticancer, anti-inflammatory, antioxidant, antibacterial, and anti-diabetic activities. Several scientific research databases, including Google Scholar, Web of Science, PubMed, SciFinder, SpringerLink, Science Direct, Scopus, and, Wiley Online were used to gather the data on hispolon until May 2024. The in vitro and in vivo studies have revealed that hispolon exhibited significant anticancer properties through modifying several signaling pathways including cell apoptosis, cycle arrest, autophagy, and inhibition of angiogenesis and metastasis. Hispolon's antimicrobial activity was proven against many bacterial, fungal, and viral pathogens, highlighting its potential use as a novel antimicrobial agent. Additionally, hispolon displayed potent anti-inflammatory activity through the suppression of key inflammatory mediators, such as inducible NO synthase (iNOS), tumor necrosis factor-α (TNF-α), and cyclooxygenases-2 (COX-2), and the modulation of mitogen-activated protein kinases (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways. The antioxidant potential of hispolon was attributed to its capacity to neutralize reactive oxygen species (ROS) and to increase the activity of antioxidant enzymes, indicating a possible involvement in the prevention of oxidative stress-related illnesses. Hispolon's antidiabetic activity was associated with the inhibition of aldose reductase and α-glucosidase. Studies on hispolon emphasized its potential use as a promising scaffold for the development of novel therapeutic agents targeting various diseases, including cancer, infectious diseases, inflammatory disorders, and diabetes.