Synthesis and Characterization of CoII Macrocycles and its Use for Promoting Hydrolysis of Esters

The design and synthesis of hydrolytically active macrocycles mimic the substrate selectivity and rate enhancements for the hydrolysis of various organic substrates in high/low temperatures and extreme pH conditions, which is extremely challenging. In the present study, we synthesized two CoIIHMTAA-14 and CoIIHMTAA-16 macrocycles (HMTAA=hexamethyl-dibenzo-tetraaza-azulene) and used them to promote the hydrolysis of 4-nitrophenyl-2-benzamide carbonate and 4-nitrophenyl-4-benzamide carbonate esters. The effect of pH on hydrolysis of the carbonate esters was also studied at different pH 4.0, 6.5, and 8.5. The results of these studies showed that the reaction follows the first order with respect to ester concentration and is independent of the medium pH and water concentration. For the account of mechanism, hydrolysis of 4-nitrophenyl-2-benzamide carbonate and 4-nitrophenyl-4-benzamide carbonate proceeds either through oxygen or nitrogen intermolecular attack and normal H2O or OH- attacks, respectively. The plots of logkobs vs. pKa of the conjugate acid nucleophile showed leveling beyond pKa of about β = 0.3. The present macrocyclic complexes were found to provide enhanced hydrolysis of the esters.

Hydrolysis of esters and dialkyl malonates mediated by t-BuNH2/LiBr/alcohol/H2O

Se describe una metodología eficiente y sencilla para la hidrólisis de ésteres y monohidrólisis de malonatos de dialquilo con el uso de t-BuNH2/MeOH/H2O con y sin LiBr. El método es de aplicación general debido a que los ésteres de Me, Et, i-Pr, t-Bu, Bn y alilo se hidrolizan adecuadamente para dar los ácidos carboxílicos correspondientes en excelentes rendimientos. El alcance del procedimiento se exploró para la desprotección de monoésteres alifáticos, aromáticos e insaturados, así como de malonatos de dialquilo. Las reacciones son, en general, muy limpias, dan rendimientos altos y no se obtienen subproductos. La selectividad del método se demostró mediante la hidrólisis de ésteres en presencia de un grupo protector N-Boc.

Butyrylcholinesterase: A Multifaceted Pharmacological Target and Tool

Butyrylcholinesterase is a serine hydrolase that catalyzes the hydrolysis of esters in the body. Unlike its sister enzyme acetylcholinesterase, butyrylcholinesterase has a broad substrate scope and lower acetylcholine catalytic efficiency. The difference in tissue distribution and inhibitor sensitivity also points to its involvement external to cholinergic neurotransmission. Initial studies on butyrylcholinesterase showed that the inhibition of the enzyme led to the increment of brain acetylcholine levels. Further gene knockout studies suggested its involvement in the regulation of amyloid-beta, a brain pathogenic protein. Thus, it is an interesting target for neurological disorders such as Alzheimer’s disease. The substrate scope of butyrylcholinesterase was recently found to include cocaine, as well as ghrelin, the “hunger hormone”. These findings led to the development of recombinant butyrylcholinesterase mutants and viral gene therapy to combat cocaine addiction, along with in-depth studies on the significance of butyrylcholinesterase in obesity. It is observed that the pharmacological impact of butyrylcholinesterase increased in tandem with each reported finding. Not only is the enzyme now considered an important pharmacological target, it is also becoming an important tool to study the biological pathways in various diseases. Here, we review and summarize the biochemical properties of butyrylcholinesterase and its roles, as a cholinergic neurotransmitter, in various diseases, particularly neurodegenerative disorders.

A self-confinement synthesis of a POM-decorated MOF thin film for actively hydrolyzing ethyl acetate

A solid acid catalyst POM@MOF thin film was prepared and utilized for the efficient hydrolysis of esters with a long durability.