A focused sulfated glycoconjugate Ugi library for probing heparan sulfate-binding angiogenic growth factors

A dual-modified glucomannan polysaccharide selectively sequesters growth factors for skin tissue repair

Artificial dermal matrixes (ADMs) are valuable clinical options for treating large soft tissue defects, but their suboptimal bioactivities compared with the real tissue limit their therapeutic potential. For example, glycosaminoglycan (GAG) polysaccharides in the native skin vitally and differentially regulate endogenous growth factors (GFs) to maintain tissue homeostasis. However, the GAG used in the current ADMs has often lost such delicate regulation. Here, we developed a novel polysaccharide-based ADM that can promote skin tissue repair through selective modulation of specific pro-healing GFs. First, we prepared a plant-derived backbone of glucomannan (named BSP) - representing the two dominant monosaccharide components in the human body - in mass and homogenic quality. Then, we modified this backbone with sulfate and acetyl groups in a controlled manner to yield an optimized BSP derivative (SMAL-BSP) as a main composition to generate a new ADM. In vitro, SMAL-BSP enabled the ADM to selectively sequester pro-angiogenic GFs of VEGF-A and FGF-2 in situ for stimulating endothelial cell growth. Moreover, the addition of the acetyl group induced macrophages to secrete nitric oxide (NO) with antibacterial activities. Further in vivo tests in a rat model of full-thickness skin wounds indicated that SMAL-BSP ADM could sequester GFs in situ to promote angiogenesis and thus tissue regeneration, with superior effects than conventional chondroitin sulfate-based ADM, while showing no adverse effects often associated with animal-derived products. Our study represents a novel strategy for ADM design, targeting selective GF sequestration towards optimal skin tissue regeneration.

From Cancer to COVID-19: A Perspective on Targeting Heparan Sulfate-Protein Interactions

Heparan sulfate (HS) is a complex, polyanionic polysaccharide ubiquitously expressed on cell surfaces and in the extracellular matrix. HS interacts with numerous proteins to mediate a vast array of biological and pathological processes. Inhibition of HS-protein interactions is thus an attractive approach for new therapeutic development for cancer and infectious diseases, including COVID-19; however, synthesis of well-defined native HS oligosaccharides remains challenging. This has aroused significant interest in the development of HS mimetics which are more synthetically tractable and have fewer side effects, such as undesired anticoagulant activity. This account provides a perspective on the design and synthesis of different classes of HS mimetics with useful properties, and the development of various assays and molecular modelling tools to progress our understanding of their interactions with HS-binding proteins.

Heparin Binding Proteins as Therapeutic Target: An Historical Account and Current Trends

The polyanionic nature and the ability to interact with proteins with different affinities are properties of sulfated glycosaminoglycans (GAGs) that determine their biological function. In designing drugs affecting the interaction of proteins with GAGs the challenge has been to generate agents with high binding specificity. The example to emulated has been a heparin-derived pentasaccharide that binds to antithrombin-III with high affinity. However, the portability of this model to other biological situations is questioned on several accounts. Because of their structural flexibility, oligosaccharides with different sulfation and uronic acid conformation can display the same binding proficiency to different proteins and produce comparable biological effects. This circumstance represents a formidable obstacle to the design of drugs based on the heparin scaffold. The conceptual framework discussed in this article is that through a direct intervention on the heparin-binding functionality of proteins is possible to achieve a high degree of action specificity. This objective is currently pursued through two strategies. The first makes use of small molecules for which in the text we provide examples from past and present literature concerning angiogenic factors and enzymes. The second approach entails the mutagenesis of the GAG-binding site of proteins as a means to generate a new class of biologics of therapeutic interest.

Synthesis of C-terminal glycopeptidesviaoxime resin aminolysis

We developed a general solid-phase approach to complex C-terminal glycopeptides.

Heparin Mimetics: Their Therapeutic Potential

Heparin mimetics are synthetic and semi-synthetic compounds that are highly sulfated, structurally distinct analogues of glycosaminoglycans. These mimetics are often rationally designed to increase potency and binding selectivity towards specific proteins involved in disease manifestations. Some of the major therapeutic arenas towards which heparin mimetics are targeted include: coagulation and thrombosis, cancers, and inflammatory diseases. Although Fondaparinux, a rationally designed heparin mimetic, is now approved for prophylaxis and treatment of venous thromboembolism, the search for novel anticoagulant heparin mimetics with increased affinity and fewer side effects remains a subject of research. However, increasingly, research is focusing on the non-anticoagulant activities of these molecules. Heparin mimetics have potential as anti-cancer agents due to their ability to: (1) inhibit heparanase, an endoglycosidase which facilitates the spread of tumor cells; and (2) inhibit angiogenesis by binding to growth factors. The heparin mimetic, PI-88 is in clinical trials for post-surgical hepatocellular carcinoma and advanced melanoma. The anti-inflammatory properties of heparin mimetics have primarily been attributed to their ability to interact with: complement system proteins, selectins and chemokines; each of which function differently to facilitate inflammation. The efficacy of low/non-anticoagulant heparin mimetics in animal models of different inflammatory diseases has been demonstrated. These findings, plus clinical data that indicates heparin has anti-inflammatory activity, will raise the momentum for developing heparin mimetics as a new class of therapeutic agent for inflammatory diseases.

Improvement on binding of chondroitin sulfate derivatives to midkine by increasing hydrophobicity

The relative binding affinities of sulfated, fully protected chondroitin sulfate oligosaccharides for midkine are much higher than those displayed by the natural deprotected sequences.

Recent advances in multicomponent reactions involving carbohydrates

Being an attractive class of naturally occurring molecules with fascinating properties, sugars and their derivatives have wide applications in different fields especially in drug discovery.

Tritylamine as an ammonia surrogate in the Ugi tetrazole synthesis

The role of tritylamine is introduced as a convenient ammonia substitute in the Ugi tetrazole synthesis. Fifteen examples and their mild cleavage products are described in satisfactory to good yields. N-Unsubstituted α-aminotetrazoles are important compounds with annotated biological activities, and the described two-step synthesis provided an alternative route to otherwise difficult to access derivatives.