Inhibition of monoamine oxidase B by N-methyl-2-phenylmaleimides

Single Heterocyclic Compounds as Monoamine Oxidase Inhibitors: From Past to Present

Inhibitors of monoamine oxidase (MAO) have shown therapeutic values in a variety of neurodegenerative diseases such as depression, Parkinson's disease and Alzheimer's disease. Heterocyclic compounds exhibit a broad spectrum of biological activities and vital leading compounds for the development of chemical drugs. Herein, we focus on the synthesis and screening of novel single heterocyclic derivatives with MAO inhibitory activities during the past decade. This review covers recent pharmacological advancements of single heterocyclic moiety along with structure- activity relationship to provide better correlation among different structures and their receptor interactions.

HFIP-promoted Michael reactions: direct para-selective C-H activation of anilines with maleimides

The Michael reaction is widely used for the C-C coupling of electron-poor olefins and C(sp3)-H pronucleophiles. Herein, an effective Michael reaction approach between electron-rich aromatic and heteroaromatic substrates as C(sp2)-H nucleophiles with maleimides as electrophiles in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was first presented without the need for any additional metal catalysts or reagents. This reaction provides a concise and environmentally friendly strategy for the facile construction of 3-aryl succinimides from N,N-disubstituted anilines and maleimides with high para selectivity.

Identification and Characterization of Novel Compounds Blocking Shiga Toxin Expression in Escherichia coli O157:H7

Infections caused by Shiga toxin (Stx)-producing E. coli strains constitute a health problem, as they are problematic to treat. Stx production is a key virulence factor associated with the pathogenicity of enterohaemorrhagic E. coli (EHEC) and can result in the development of haemolytic uremic syndrome in infected patients. The genes encoding Stx are located on temperate lysogenic phages integrated into the bacterial chromosome and expression of the toxin is generally coupled to phage induction through the SOS response. We aimed to find new compounds capable of blocking expression of Stx type 2 (Stx2) as this subtype of Stx is more strongly associated with human disease. High-throughput screening of a small-molecule library identified a lead compound that reduced Stx2 expression in a dose-dependent manner. We show that the optimized compound interferes with the SOS response by directly affecting the activity and oligomerization of RecA, thus limiting phage activation and Stx2 expression. Our work suggests that RecA is highly susceptible to inhibition and that targeting this protein is a viable approach to limiting production of Stx2 by EHEC. This type of approach has the potential to limit production and transfer of other phage induced and transduced determinants.

Selective and tunable synthesis of 3-arylsuccinimides and 3-arylmaleimides from arenediazonium tetrafluoroborates and maleimides

A highly efficient and tunable synthetic strategy for 3-arylsuccinimides or 3-arylmaleimides has been developed from arenediazonium tetrafluoroborates and maleimides with satisfactory yields in the presence of TiCl₃ or CuCl.

Reactivity and kinetics of vinyl sulfone-functionalized self-assembled monolayers for bioactive ligand immobilization

A new vinyl sulfone (VS) disulfide, 1,2-bis(11-(vinyl sulfonyl)undecyl)disulfane, was synthesized to enable the preparation of VS-presenting self-assembled monolayers (VS SAMs) on Au substrates. The VS SAMs were used as a model system to assess the reaction kinetics of bioactive ligands, i.e., glutathione (GSH), N-(5-amino-1-carboxypentyl)iminodiacetic acid (ab-NTA), and mannose, toward the VS groups on the SAM surface. The VS SAMs and the ligand immobilization were characterized by X-ray photoelectron spectroscopy (XPS), contact angle goniometry, and protein-binding experiments using a quartz crystal microbalance (QCM). Kinetic studies showed that the surface VS groups undergo pseudo-first-order reactions with various ligands, with the observed rate constant being 0.057 min(-1) for GSH at pH 7.5, 0.011 min(-1) for ab-NTA at pH 8.5, and 0.009 min(-1) for mannose at pH 10.5. This work advanced our understanding of the reactivity of VS-bearing functional surfaces and further demonstrated the versatile potential of VS chemistry to prepare ligand-immobilized bioactive surfaces.

Effect of some pyrimidine compounds on rat brain monoamine oxidase-B in vitro

The effects of some pyrimidine compounds (PCs) including barbituric acid (BA) 5,5-diethyl barbituric acid (DEBA), 2-thiobarbituric acid (TBA), violuric acid (VA), 2-thiouracil (TU), and 6-amino-2-thiouracil (ATU) on the activity of rat brain monoamine oxidase-B (MAO-B) were investigated. The results revealed that MAO-B was activated by BA, DEBA, TBA, TU, and ATU, and the activation was structural, concentration, and time dependent. However, MAO-B was inhibited by VA in a noncompetitive and irreversible manner with an enzyme-inhibitor dissociation constant (K (i) value) of 32 nM and IC(50) equals to 19 nM. All the studied PCs changed both the optimum pH and temperature of MAO-B.

Cancer-targeting Antibody–Drug Conjugates: Site-specific Conjugation of Doxorubicin to Anti-EGFR 528 Fab' through a Polyethylene Glycol Linker

Antibody–drug conjugates have been prepared to examine the effect that attaching small-molecule drugs to an antibody fragment has on antibody activity. The anticancer drug doxorubicin was covalently attached through a polyethylene glycol linker to a cancer-targeting, anti-epidermal growth factor receptor antibody fragment (Fab′). The reactivity of maleimide was compared with a substituted maleimide derivative (citraconimide) in conjugation reactions with cysteine residues on a Fab′. Introduction of polyethylene glycol increased aqueous solubility of the cytotoxic drug, which led to an improvement in overall yield of the conjugation reaction with the antibody fragment. Antibody–drug conjugates prepared retained activity of the parent antibody, as determined by antigen binding experiments measured by surface plasmon resonance.