The high affinity of highly charged polynuclear platinum complexes for glycans such as heparan sulfate results in modulation of the biomolecule signaling functions leading to inhibition of angiogenesis.

Extracellular histones in neutrophil extracellular traps (NETs) or in chromatin from injured tissues are highly pathological, particularly when liberated by DNases. We report the development of small polyanions (SPAs) (~0.9–1.4 kDa) that interact electrostatically with histones, neutralizing their pathological effects. In vitro, SPAs inhibited the cytotoxic, platelet-activating and erythrocyte-damaging effects of histones, mechanistic studies revealing that SPAs block disruption of lipid-bilayers by histones. In vivo, SPAs significantly inhibited sepsis, deep-vein thrombosis, and cardiac and tissue-flap models of ischemia-reperfusion injury (IRI), but appeared to differ in their capacity to neutralize NET-bound versus free histones. Analysis of sera from sepsis and cardiac IRI patients supported these differential findings. Further investigations revealed this effect was likely due to the ability of certain SPAs to displace histones from NETs, thus destabilising the structure. Finally, based on our work, a non-toxic SPA that inhibits both NET-bound and free histone mediated pathologies was identified for clinical development.

Heparin and heparan sulfate (HS) are structurally diverse glycosaminoglycans (GAG) that are known to interact, via unique structural motifs, with a wide range of functionally distinct proteins and modulate their biological activity. To define the GAG motifs that interact with proteins, we assessed the ability of 15 totally synthetic HS mimetics to interact with 10 functionally diverse proteins that bind heparin/HS. The HS mimetics consisted of cyclitol-based pseudo-sugars coupled by linkers of variable chain length, flexibility, orientation, and hydrophobicity, with variations in sulfation also being introduced into some molecules. Three of the proteins tested, namely hepatocyte growth factor, eotaxin, and elastase, failed to interact with any of the sulfated linked cyclitols. In contrast, each of the remaining seven proteins tested exhibited a unique reactivity pattern with the panel of HS mimetics, with tetrameric cyclitols linked by different length alkyl chains being particularly informative. Thus, compounds with short alkyl spacers (2-3 carbon atoms) effectively blocked the interaction of fibroblast growth factor-1 (FGF-1) and lipoprotein lipase with heparin/HS, whereas longer chain spacers (7-10 carbon atoms) were required for optimal inhibition of FGF-2 and vascular endothelial growth factor binding. This effect was most pronounced with the chemokine, interleukin-8, where alkyl-linked tetrameric cyclitols were essentially inactive unless a spacer of >7 carbon atoms was used. The heparin-inhibitable enzymes heparanase and cathepsin G also displayed characteristic inhibition patterns, cathepsin G interacting promiscuously with most of the sulfated cyclitols but heparanase activity being inhibited most effectively by HS mimetics that structurally resemble a sulfated pentasaccharide. These data indicate that a simple panel of HS mimetics can be used to probe the HS binding specificity of proteins, with the position of anionic groups in the HS mimetics being critical. Heparan sulfate (HS)1 is a glycosaminoglycan that is ubiquitously expressed as a proteoglycan on cell surfaces and throughout the extracellular matrix (ECM) in most multicellular animals (1-5). The polysaccharide is composed of alternating glucuronic acid and N-acetylglucosamine units, which, during biosynthesis, are subjected to a range of modifications such as O-sulfation at various positions, N-deacetylation, and Nsulfation of N-acetylglucosamine residues as well as C-5 epimerization of glucuronic acid to iduronic acid. Theoretically up to 48 different disaccharides could occur in HS due to these modifications, although so far only 23 have been identified (2). Nevertheless, as a result of the presence of these different disaccharides, HS chains exhibit remarkable structural heterogeneity. Such diversity is further enhanced by the considerable variation in chain length of the glycosaminoglycan. Heparin, a glycosaminoglycan with a much more restricted cellular distribution than HS, is structurally closely related to HS but has ϳ80% of its disacc...