Design, synthesis and biological evaluation of tricyclic pyrazolo[1,5-c][1,3]benzoxazin-5(5H)-one scaffolds as selective BuChE inhibitors

Abstract

Based on the structural analysis of tricyclic scaffolds as butyrylcholinesterase (BuChE) inhibitors, a series of pyrazolo[1,5-c][1,3]benzoxazin-5(5H)-one derivatives were designed, synthesized and evaluated for their acetylcholinesterase (AChE) and BuChE inhibitory activity. Compounds with 5-carbonyl and 7- or/and 9-halogen substitutions showed potential BuChE inhibitory activity, among which compounds 6a, 6c and 6g showed the best BuChE inhibition (IC50 = 1.06, 1.63 and 1.63 µM, respectively). The structure–activity relationship showed that the 5-carbonyl and halogen substituents significantly influenced BuChE activity. Compounds 6a and 6g were found nontoxic, lipophilic and exhibited remarkable neuroprotective activity and mixed-type inhibition against BuChE (Ki = 7.46 and 3.09 µM, respectively). Docking studies revealed that compound 6a can be accommodated into BuChE via five hydrogen bonds, one Pi–Sigma interaction and three Pi–Alkyl interactions.

Structure–activity relationship, in vitro and in vivo evaluation of novel dienyl sulphonyl fluorides as selective BuChE inhibitors for the treatment of Alzheimer's disease

“…The inhibitory potency of dienyl sulphonyl fluorides with α-substituent was assessed by Ellman’s assay on Electrophorus electricus AChE ( Ee AChE) and equine BuChE (eqBuChE). The IC 50 values were obtained and compared to the reference donepezil, which is a FDA-approved selective AChE inhibitor that simultaneously binds to catalytic active and peripheral anionic sites, providing moderate inhibition of Aβ aggregation 49 , 50 . The IC 50 values of all tested compounds against Ee AChE and eqBuChE were summarised in Table 1 .…”

“…To determine the potency and selectivity of compounds A10 and A18 for the human enzymes, ChE inhibitory activity was assessed by Ellman’s assay on recombinant human AChE (hAChE) and BuChE from human serum (hBuChE) 49 , 50 . Compared to the positive control rivastigmine, compound A10 showed close inhibitory effect on hBuChE and stronger inhibitory effect on hAChE at 20 µM ( Table 2 ).…”

“…As shown in Figure 5(A) , in the presence of different concentrations of A10 , the change curve of enzyme activity with enzyme concentration (0, 0.045, 0.090, 0.18, 0.36 and 0.72 U/mL) was a series of straight lines and intersected at one point, and the line slope decreased with the increase of inhibitor concentration, indicating that compound A10 was a reversible BuChE inhibitor. Kinetic types of enzyme inhibition were obtained by the improved Ellman method and Lineweaver-Burk secondary diagrams, and typically, Lineweaver − Burk curves can be represented by reciprocal rates versus reciprocal substrate concentrations 50 , 51 . As shown by Figure 5(B) , with the increase of compound A10 concentration, Lineweaver–Burk plot showed higher slope (decreased V max ) and higher intercept (higher K m ), and the trend was usually attributed to mixed inhibition, and the dissociation constant K i of compound A10 was estimated to be 29 nM in Lineweaver–Burk secondary plot.…”

“…As shown in Figure 5(A), in the presence of different concentrations of A10, the change curve of enzyme activity with enzyme concentration (0, 0.045, 0.090, 0.18, 0.36 and 0.72 U/mL) was a series of straight lines and intersected at one point, and the line slope decreased with the increase of inhibitor concentration, indicating that compound A10 was a reversible BuChE inhibitor. Kinetic types of enzyme inhibition were obtained by the improved Ellman method and Lineweaver-Burk secondary diagrams, and typically, Lineweaver À Burk curves can be represented by reciprocal rates versus reciprocal substrate concentrations 50,51 . As shown by…”

Novel Pyridine‐Containing Sultones: Structure‐Activity Relationship and Biological Evaluation as Selective AChE Inhibitors for the Treatment of Alzheimer's disease

“…Compound B4 with the best inhibitory activity was selected for enzyme kinetic analysis to determine its kinetics of AChE inhibition [28] . As shown in Figure 5A, in the presence of different concentrations of compound B4 , the relationship curve between the residual enzyme activity of acetylcholine and the enzyme concentration (0.01125, 0.0225, 0.045, 0.090, 0.18 and 0.36 U/mL) showed a series of straight lines.…”