Plasmin inhibitors with hydrophobic amino acid-based linker between hydantoin moiety and benzimidazole scaffold enhance inhibitory activity

Exploration of Active Site-Directed Plasmin Inhibitors: Beyond Tranexamic Acid

Plasmin (Plm), a trypsin-like serine protease, is responsible for fibrinolysis pathway and pathologic events, such as angiogenesis, tumor invasion, and metastasis, and alters the expression of cytokines. A growing body of data indicates that a Plm inhibitor is a potential candidate as an anti-inflammatory and anti-cancer agent. A class of active site-directed plasmin inhibitors containing tranexamic acid residue has been designed. As evidenced by docking studies, the inhibitor binds to the active site not to the lysine binding site (LBS) in plasmin, thus preventing plasmin from digesting the substrate. Further optimization of the series, concerning both activity and selectivity, led to the second generation of inhibitors. This review focuses on the Plm inhibitory activity-structure relationship of Plm inhibitors with the goal of realizing their design and clinical application.

Fibrinolysis Inhibitors: Potential Drugs for the Treatment and Prevention of Bleeding

Hyperfibrinolytic situations can lead to life-threatening bleeding, especially during cardiac surgery. The approved antifibrinolytic agents such as tranexamic acid, ε-aminocaproic acid, 4-aminomethylbenzoic acid, and aprotinin were developed in the 1960s without the structural insight of their respective targets. Crystal structures of the main antifibrinolytic targets, the lysine binding sites on plasminogen's kringle domains, and plasmin's serine protease domain greatly contributed to the structure-based drug design of novel inhibitor classes. Two series of ligands targeting the lysine binding sites have been recently described, which are more potent than the most-widely used antifibrinolytic agent, tranexamic acid. Furthermore, four types of promising active site inhibitors of plasmin have been developed: tranexamic acid conjugates targeting the S1 pocket and primed sites, substrate-analogue linear homopiperidylalanine-containing 4-amidinobenzylamide derivatives, macrocyclic inhibitors addressing nonprimed binding regions, and bicyclic 14-mer SFTI-1 analogues blocking both, primed and nonprimed binding sites of plasmin. Furthermore, several allosteric plasmin inhibitors based on heparin mimetics have been developed.

Fate of dissolved organic nitrogen during the Anammox process using ultra-high resolution mass spectrometry

Anaerobic ammonium oxidation (Anammox) is a cost-effective process for treating highly nitrogenous wastewater. However, the fate of organic nitrogen during Anammox treatment is still unclear, which limits its practical application. In this work, the changes in the quality of dissolved organic nitrogen (DON) in coal liquefaction wastewater (CLW) during Anammox were studied in relation to its chemical composition, which was determined by Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The molecular-level characterization of extracellular polymeric substances (EPS) in the Anammox sludge is also reported for the first time in this paper. The relative contribution of N-containing compounds to the total dissolved organic matter (DOM) determined by summating the normalized intensities exceeded 30%, highlighting the complexity of the nitrogenous compounds in the influent. Additionally, Anammox appeared to be better suited to removing DON compounds with fewer carbonyl or carboxyl groups, more aromatic structures, and higher oxidative properties. Lignin-like substances were verified as the predominant component of N-containing compounds in Anammox EPS, followed by protein and substances with condensed aromatic structures. DON compounds with higher degrees of saturation, lower molecular weight, and higher lignin-like properties were more prone to absorption by Anammox EPS. A series of microbe-mediated pathways were demonstrated to be responsible for DON biodegradation, which revealed the organic and inorganic nitrogen removal mechanisms in the Anammox reactor. The obtained results provide great support to the ongoing efforts to optimize the Anammox process.

Recent Advances in the Synthesis of Hydantoins: The State of the Art of a Valuable Scaffold

The review highlights the hydantoin syntheses presented from the point of view of the preparation methods. Novel synthetic routes to various hydantoin structures, the advances brought to the classical methods in the aim of producing more sustainable and environmentally friendly procedures for the preparation of these biomolecules, and a critical comparison of the different synthetic approaches developed in the last twelve years are also described. The review is composed of 95 schemes, 8 figures and 528 references for the last 12 years and includes the description of the hydantoin-based marketed drugs and clinical candidates.

Discovery and optimization of benzimidazole derivatives as a novel chemotype of farnesoid X receptor (FXR) antagonists

We describe here a novel chemotype with substituted benzimidazole scaffold for nonsteroidal farnesoid X receptor (FXR) antagonists starting from the identification of a screening hit, BB-4. Structure diversity in four regions A-D of BB-4 or 1 is discussed. In particular, regions A and C had an effect on an antagonism against FXR as demonstrated by the derivatives represented by 7 and 15, respectively. Thus, compound 19 arising from the combination of regions A and C underscored an important fact on antagonism against FXR, also showing the reduced small heterodimer partner and the increased cholesterol 7α-hydroxylase expression levels.