Chemical modification of horseradish peroxidase with several methoxypolyethylene glycols

The chemical modification of ε-NH₂ lysine residues of horseradish peroxidase (E.C. 1.11.1.7) with several mPEG was carried out. The modified enzymes were studied through Chromatographic and electrophoretic methods; the extent of mPEG linking was determined using¹H-NMR. Peroxidase, modified with mPEG ranging from 350 to 5000, activated with 4-nitrophenylchloroformate (mPEGpn), showed a better thermal stability than the native, but there was no correlation between the length of the polymer adduct and the improvement. The enzyme was modified with mPEG (5000) activated by cyanuric chloride (mPEGcc). The number of modified lysine increased, but the thermal behavior of mPEGcc peroxidase was similar to those of mPEGpn enzymes. In all cases, the modification did not markedly change the stability in organic solvents.     

Reduction‐responsive poly (ethylene glycol)‐dexamethasone biarm conjugate and its self‐assembled nanomicelles: Preparation,physicochemical characterization,and thiol‐triggered drug release

In this study, a reduction‐responsive poly (ethylene glycol)‐dexamethasone biarm conjugate was synthesized as intracellular targeted drug delivery carriers. The hydroxyl end group of methoxy poly (ethylene glycol) (mPEG) was modified to introduce a biarm structure with bioreducible disulfide bond and amine end groups. Dexamethasone (Dex) as a nuclear targeting moiety was conjugated to the amine end groups of mPEG biarm derivatives, mPEG‐(NH₂)₂ or mPEG‐(ss‐NH₂)₂, with or without bioreducible disulfide bonds. The bioreducible and nonreducible mPEG‐Dex biarm conjugates, R‐mPEG‐Dex and N‐mPEG‐Dex, were synthesized and characterized by various analytical methods, proton nuclear magnetic resonance (¹H‐NMR), Fourier transform infraredspectroscopy (FT‐IR), dynamic light scattering (DLS), and fluorescence measurements. Amphiphilic mPEG‐Dex conjugates self‐assembled in aqueous solutions to form nanoparticles (NPs) with a size range of 130 to 150 nm, and their critical micelle concentrations (CMCs) were determined to be 12.4 and 15.3 mg/L, respectively, for bioreducible and nonreducible ones. The R‐mPEG‐Dex NPs maintained good colloidal stability in the presence of bovine serum albumin (BSA) for more than 1 week but demonstrated a significant change in colloidal stability in the presence of dithiothreitol (DTT). In DTT‐containing phosphate‐buffered saline (PBS), the bioreducible NPs showed not only reduction‐responsive destabilization with PEG shedding but also thiol‐dependent drug release profile. Our observations indicated that the R‐mPEG‐Dex NPs have a promising prospective as an efficient nanocarrier for intracellular targeted delivery of various anticancer drugs.     

Y‐shaped poly(ethylene glycol) and poly(trimethylene carbonate) amphiphilic copolymer: Synthesis and for drug delivery

New Y‐shaped (AB₂‐type) amphiphilic copolymers of poly(ethylene glycol) (PEG) with poly(trimethylene carbonate) (PTMC), PEG‐b‐(PTMC)₂, were successfully synthesized by the ring‐opening polymerization (ROP) of TMC with bishydroxy‐modified monomethoxy‐PEG (mPEG). First, a bishydroxy functional ROP initiator was synthesized by esterification of acryloyl bromide with mPEG, followed by Michael addition using excess diethanolamine. A series of Y‐shaped amphiphilic PEG‐(PTMC)₂ block copolymers were obtained via ROP of TMC using this PEG with bishydroxyl end groups as macroinitiator and ZnEt₂ as catalyst. The amphiphilic block copolymers with different compositions were characterized by gel permeation chromatography (GPC) and ¹H NMR, and their molecular weight was measured by GPC. The results showed that the molecular weight of Y‐shaped copolymers increased with the increase of the molar ratio of TMC to mPEG‐(OH)₂ initiator in feed while the PEG chain length was kept constant. The Y‐shaped copolymer mPEG‐(PTMC)₂ could self‐assemble into micelles in aqueous medium and the critical micelle concentration values of the micelles decrease with increase in hydrophobic PTMC block length of mPEG‐(PTMC)₂. The in vitro cytotoxicity and controlled drug release properties of the Y‐shaped amphiphilic block copolymers were also investigated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8131–8140, 2008     

1,3,5-Triazine Nitrogen Mustards with Different Peptide Group as Innovative Candidates for AChE and BACE1 Inhibitors

A series of new analogs of nitrogen mustards (4a–4h) containing the 1,3,5-triazine ring substituted with dipeptide residue were synthesized and evaluated for the inhibition of both acetylcholinesterase (AChE) and β-secretase (BACE1) enzymes. The AChE inhibitory activity studies were carried out using Ellman’s colorimetric method, and the BACE1 inhibitory activity studies were carried out using fluorescence resonance energy transfer (FRET). All compounds displayed considerable AChE and BACE1 inhibition. The most active against both AChE and BACE1 enzymes were compounds A and 4a, with an inhibitory concentration of AChE IC₅₀ = 0.051 µM; 0.055 µM and BACE1 IC₅₀ = 9.00 µM; 11.09 µM, respectively.     

Immobilization ofAspergillus niger NRC 107 xylanase and β-xylosidase,and properties of the immobilized enzymes

Aspergillus niger NRC 107 xylanase and β-xylosidase were immobilized on various carriers by different methods of immobilization, including physical adsorption, covalant binding, ionic binding, and entrapment. The immobilized enzymes were prepared by physical adsorption on tannin-chitosan, ionic binding onto Dowex-50W, covalent binding on chitosan beads through glutaraldehyde, and entrapment in polyacrylamide had the highest activities. In most cases, the optimum pH of the immobilized enzymes were shifted to lower than those of free enzymes. The optimum reaction temperature of immobilized xylanase was shifted from 50°C to 52.5–65°C, whereas that of immobilized β-xylosidase was shifted from 45°C to 50–60°C. TheK _m values of immobilized enzymes were higher than those of native enzymes. The operational stability of the immobilized enzymes was evaluated in continuous operation in packed-bead column-type reactors. The enzymes covalently bounded to chitosan showed the highest operational stability. However, the enzymes immobilized by physical adsorption or by ionic binding showed a low operational stability. The enzymes entrapped in polyacrylamide exhibited lower activity, but better operational stability.     

Kinetic and thermodynamic study of a chemically modified highly active xylanase fromScopulariopsis sp

The amino groups of purified least acidic xylanase (LAX) isomer and carboxyl groups of purified highly acidic xylanase (HAX) isomer fromScopulariopsis sp. were chemically modified, resulting in charge neutralization and reversal. Modification of the second amino group was accompanied by the complete loss of enzyme activity in both the absence and presence of xylose. Multiple alignments of family 10 and 11 xylanases revealed that there is a pair of fully conserved Lys residues only in family 10 members. Xylanase structures from family 10 members showed that one of the conserved Lys residues is found near the active-site cleft that makes an H-bond with the substrate. The LAX and HAX isoenzymes in which one amino and three to four carboxyl groups were modified were subjected to kinetic and thermodynamic characterization. There were no differences in pH optima between the native and modified HAX, but there was a broadening of pH optimum toward the alkaline range for charge-neutralized LAX and a double pH optimum for charge-reversed LAX. TheV _max/K _m of both modified LAX and HAX decreased relative to the native species. The thermodynamics of xylan hydrolysis showed that the decrease in the catalytic activity of modified LAX enzymes was entropically driven. When compared with native enzyme, the thermostabilities of modified LAX enzymes increased in the presence and decreased in the absence of substrate. The thermodynamics of kinetic stability for modified LAX enzymes revealed that this increase in thermolability was owing to the decrease in ΔH# with a concomitant increase in ΔS# compared with native LAX. The thermostabilities of all the modified HAX species decreased except that of charge-neutralized HAX, whose half-life significantly increased in 50% (v/v) aqueous dioxan. These results suggest that the altered properties of the modified enzymes were a result of the conformational changes brought about by chemical modification. An erratum to this article is available at .     

Associative diblock copolymers of poly(ethylene glycol) and coiled-coil peptides

A series of peptides of general primary structure (VSSLESK)_n (n = 2, 3, 4, 5 and 6) were designed and synthesized by fluorenylmethyloxycarbonyl solid-phase synthesis using a convergent approach. Peptides containing 21, 28, 35 and 42 residues were modified with α-methoxy poly(ethylene glycol) (mPEG; mol. wt. 2000) by reaction of mPEG–succinimidyl carbonate with the α-amino group of the resin-attached protected peptides. The conformation and thermal stability of the peptides and of their AB block copolymers (A is the mPEG block, B the (VSSLESK)_n block) in aqueous medium were investigated by circular dichroism, size-exclusion chromatography and by analytical ultracentrifugation. The helicity of peptides increased with increasing length in a cooperative manner. The peptides and mPEG–peptides with 35 and 42 amino acid residues (block copolymers) adopted a two-stranded α-helical coiled-coil conformation in aqueous solution. The presence of the polymer chain in the diblock hybrid copolymers had no disturbing effect with respect to the stability of the α-helical peptide part in these constructs. Moreover, the thermal stability of mPEG-modified 42-peptide was substantially higher than that of the native 42-peptide. Analytical ultracentrifugation data revealed that in phosphate-buffered saline solution (25–200 μM ) the block copolymer mPEG-block-(VSSLESK)₆ ( PEG42 ) associated into stable intermolecular coiled-coil dimers.

Thermal melting profiles of peptides and mPEG–peptides at concentration 0.4 g · L⁻¹ in PBS. Molar ellipticity at 222 nm versus temperature. Heating rate 0.5 °C · min⁻¹.     

Endoglucanase and Total Cellulase from Newly Isolated Rhizopus oryzae and Trichoderma reesei: Production,Characterization, and Thermal Stability

A multienzymatic complex production was evaluated, as well as endoglucanase and total cellulase characterization, during solid-state fermentation of rice industry wastes with Rhizopus oryzae CCT 7560 (newly isolated microorganism) and Trichoderma reesei QM 9414 (control). R. oryzae produced enzymes with higher activity at 15 h of fermentation (5.1 and 2.3 U g^?1 to endoglucanase and total cellulase), while T. reesei produced them at 55 h (15.3 and 2.8 U g^?1 to endoglucanase and total cellulase). The optimum temperature for total cellulase and endoglucanase was 60 °C. For Trichoderma and Rhizopus, the optimum pH was 5.0 and 6.0 for total cellulase and 6.0 and 5.0 for endoglucanase, respectively. The enzymes produced by Rhizopus presented higher stability at the temperature range evaluated (25–100 °C); the endoglucanase K _M value was 20 times lower than the one found for Trichoderma. The characterization of the cellulolytic enzymes from the fungal species native of rice husk revealed that they can be more efficient than the genetically modified enzymes when rice husk and rice bran are used as substrates.     

Lysine modification of human serum albumin and its effect on protein conformation and nalidixic acid binding

In order to investigate the involvement of lysine residues of human serum albumin (HSA) in nalidixic acid (NA) binding, various modified preparations of HSA such as 44% carbamylated (C₄₄), 83% carbamylated (C₈₃) and 85% acetylated (A₈₅) were made by treating the HSA solution with a different molar excess of potassium cyanate and acetic anhydride. The extent of modification, charge homogeneity and conformational changes of these derivatives were checked by TNBSA reaction method, polyacrylamide gel electrophoresis (PAGE) and gel filtration using Sephacryl S-200 HR column, respectively. Binding of NA to HSA and its derivatives was examined using fluorescence quenching titration method to determine the binding constant. The emergence of a single band in PAGE and single symmetrical peak in gel filtration results confirmed the charge and size homogeneity of these derivatives. Hydrodynamic properties such as Stokes radius and frictional ratio, as obtained from the analytical gel filtration results suggested molecular expansion in C₈₃ and A₈₅ HSAs while C₄₄ HSA retained the native conformation. Addition of NA to both native and modified HSA derivatives quenched the fluorescence intensity of the protein at 344 ​nm to a different extent. Whereas the values of the Stern-Volmer constant (K_SV) and bimolecular quenching rate constant (k_q) suggested, NA-HSA complex formation, binding constant (K_a) value suggested an intermediate binding affinity between NA and HSA. Furthermore, the decrease in the K_a value with the extent of modification was indicative of the involvement of lysine residues in NA-HSA interaction.     

2-methylindole analogs as cholinesterases and glutathione S-transferase inhibitors: Synthesis,biological evaluation,molecular docking,and pharmacokinetic studies

In this study, we aimed to (i) synthesize new 2-methylindole analogs containing various amino structures, pyrrolidine, piperidine, morpholine, and substituted phenyl groups through structural and molecular modifications, (ii) evaluate the pharmaceutical potential of 2-methylindole analogs via assessing enzyme inhibitory activity against glutathione S-transferase (GST), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE), (iii) predict ADMET and pharmacokinetic properties of the synthesized 2-methylindole analogs, (iv) reveal the possible interactions between the synthesized 2-methylindole analogs with GST, AChE, and BChE enzymes using several molecular docking software. In vitro enzyme inhibition assays showed that the synthesized indole analogs exhibited moderate to good inhibitory activities against GST, AChE, and BChE enzymes. Briefly, the inhibitory activities of the analogs 4b and 4i against AChE, 4a and 4b against BChE, and analogs 1 and 4i against GST were detected to be higher or close to the standard inhibitor compounds. The analog 4b was detected to have the best inhibitory activity against both AChE and BChE enzymes with the lowest IC₅₀ values as 0.648 µM for AChE and 0.745 µM for BChE. The analyses of enzyme inhibition relationship with the synthesized analogs could help to design new analogs for the inhibitors of cholinergic and glutathione pathways based on the indole derivatives.     

A physico-chemical analysis of soluble and immobilized enzyme stabilization

The literature and our experimental data on the effect of chemical modification and immobilization on the thermostability of enzymes are analyzed. The effect of various factors causing changes in the stability of enzymes after their modification or immobilization is demonstrated. It is shown that changes in the temperature dependence of the inactivation rate constant are associated with the change in the effective values of thermodynamic activation parameters for the inactivation processes. An increase in the activation energy of thermoinactivation, E_a, leads to the stabilization of a modified or immobilized enzyme at temperatures below the iso-kinetic temperature (“low-temperature” stabilization) and a decrease inE _a entails a “high-temperature” stabilization of enzymes. It is shown that with immobilized enzymes the high-temperature stabilization is invariably observed.     

Structure Elucidation and Cholinesterase Inhibition Activity of Two New Minor Amaryllidaceae Alkaloids

Two new minor Amaryllidaceae alkaloids were isolated from Hippeastrum × hybridum cv. Ferrari and Narcissus pseudonarcissus cv. Carlton. The chemical structures were identified by various spectroscopic (one- and two-dimensional (1D and 2D) NMR, circular dichroism (CD), high-resolution mass spectrometry (HRMS) and by comparison with literature data of similar compounds. Both isolated alkaloids were screened for their human acetylcholinesterase (hAChE) and butyrylcholinesterase (hBuChE) inhibition activity. One of the new compounds, a heterodimer alkaloid of narcikachnine-type, named narciabduliine (2), showed balanced inhibition potency for both studied enzymes, with IC₅₀ values of 3.29 ± 0.73 µM for hAChE and 3.44 ± 0.02 µM for hBuChE. The accommodation of 2 into the active sites of respective enzymes was predicted using molecular modeling simulation.     

First-in-Class Isonipecotamide-Based Thrombin and Cholinesterase Dual Inhibitors with Potential for Alzheimer Disease

Recently, the direct thrombin (thr) inhibitor dabigatran has proven to be beneficial in animal models of Alzheimer’s disease (AD). Aiming at discovering novel multimodal agents addressing thr and AD-related targets, a selection of previously and newly synthesized potent thr and factor Xa (fXa) inhibitors were virtually screened by the Multi-fingerprint Similarity Searching aLgorithm (MuSSeL) web server. The N-phenyl-1-(pyridin-4-yl)piperidine-4-carboxamide derivative 1, which has already been experimentally shown to inhibit thr with a K_i value of 6 nM, has been flagged by a new, upcoming release of MuSSeL as a binder of cholinesterase (ChE) isoforms (acetyl- and butyrylcholinesterase, AChE and BChE), as well as thr, fXa, and other enzymes and receptors. Interestingly, the inhibition potency of 1 was predicted by the MuSSeL platform to fall within the low-to-submicromolar range and this was confirmed by experimental K_i values, which were found equal to 0.058 and 6.95 μM for eeAChE and eqBChE, respectively. Thirty analogs of 1 were then assayed as inhibitors of thr, fXa, AChE, and BChE to increase our knowledge of their structure-activity relationships, while the molecular determinants responsible for the multiple activities towards the target enzymes were rationally investigated by molecular cross-docking screening.     

Exploring facile synthesis and cholinesterase inhibiting potential of heteroaryl substituted imidazole derivatives for the treatment of Alzheimer’s disease

Alzheimer’s disease (AD) is a neurodegenerative disorder and cholinesterase (ChE) enzymes are considered as crucial targets for the treatment of AD. Herein, a series of heteroaryl substituted imidazole derivatives (5a-5x) was prepared using amino acid catalyzed, one-pot facile synthetic approach. In this context, the catalytic potentials of different amino acids were investigated and 15 mol% of glutamic acid was identified as the most suitable catalyst to obtain the target products in good yields up to 90 %. These structurally exciting heterocyclic hybrids were screened against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. This series displayed moderate to excellent inhibitory potential against AChE with IC₅₀ values > 25 µM and the most active compound was 3-(4-(1-(3,5-dimethylphenyl)-4,5-diphenyl-1H-imidazol-2-yl)-1-phenyl-1H-pyrazol-3-yl)–2H-chromen-2-one (5x) with IC₅₀ value of 25.83 ± 0.25 µM.This inhibitory potential was attributed to hydrophobicity as the major contributory factor. The most potent compound against BChE was 1,3-diphenyl-4-(1,4,5-triphenyl-1H-imidazol-2-yl)-1H-pyrazole (5a) with IC₅₀ value of 0.35 ± 0.02 µM followed by other potent compounds 5p, 5 m, 5x, 5b, 5c, 5e and 5f with IC₅₀ values < 10 µM. SAR studies further revealed that coumarinyl moiety at R¹ position in the imidazolylpyrazole skeleton significantly improved the overall cholinesterase inhibitory potential. However, a simple phenyl ring attached at this R¹ site was highly effective and selective for BChE inhibition (5a) over AChE. Docking data also demonstrated the interaction of 5x and AChE with a docking score of 7564 and atomic contact energy (ACE) value of –291.90 kcal/mol whereas docking score for 5a against BChE was 7096 with ACE value of –332.95 kcal/mol. The results altogether suggest further investigations of the heteroaryl substituted imidazole core skeleton in search of potential leads towards designing of new anti-cholinesterase drugs for the treatment of AD.     

A study of complexation thermodynamic of humic acid with cadmium (II) and zinc (II) by Schubert's ion-exchange method

The complexation of humic acid from Azraq Oasis with two heavy metal ions Cd(II) and Zn(II) was investigated at pH 4 and 5 under constant ionic strength of 0.1 and at different temperatures (25, 35, 45, 55 and 65 °C). This investigation was done by using Schubert's ion-exchange equilibrium method, and its modified version.The derived conditional stability constants (log β_n) for these two metal-humate complexes were determined; they formed 1:1 and 1:2 complexes. It was found that the conditional stability constants (log β_n) increased by increasing pH and temperatures for all metal-humate complexes. It was found that the conditional stability constant log β₁ for Cd-humate is bigger than Zn-humate at all the desired temperatures and at pH 4 and 5.The derived constants and their temperature dependences have been used to calculate the corresponding thermodynamic parameters ΔG, ΔH, and ΔS, the results indicate that the stability of these complexes derives from very favorable entropy.     

New naphthalene derivative for cost-effective AChE inhibitors for Alzheimer’s treatment: In silico identification,in vitro and in vivo validation

Neurodegenerative diseases have complex etiology and pose a challenge to scientists to develop simple and cost-effective synthetic compounds as potential drug candidates for such diseases. Here, we report an extension of our previously published in silico screening, where we selected four new compounds as AChE inhibitors. Further, based on favorable binding possess, MD simulation and MMGBSA, two most promising compounds (3a and 3b) were selected, keeping in view the ease of synthesis and cost-effectiveness. Due to the critical role of BChE, LOX and α-glucosidase in neurodegeneration, the selected compounds were also screened against these enzymes.The IC₅₀ values of 3a against AChE and BChE found to be 12.53 and 352.42 μM, respectively. Moderate to slight inhibitions of 45.26 % and 28.68 % were presented by 3a against LOX and α-glucosidase, respectively, at 0.5 mM. Insignificant inhibitions were observed with 3b against the four selected enzymes. Further, in vivo trial demonstrated that 3a could significantly diminish AChE levels in the mice brain as compared to the control. These findings were in agreement with the histopathological analysis of the brain tissues. The results corroborate that selected compounds could serve as a potential lead for further development and optimization as AChE inhibitors to achieve cost-effective anti-Alzheimer’s drugs.     

Synthesis and inhibition profiles of N-benzyl- and N-allyl aniline derivatives against carbonic anhydrase and acetylcholinesterase – A molecular docking study

The alkyl and aryl derivatives of aniline are important starting materials in fine organic synthesis. Allyl bromide and benzyl chloride were taken as substrates for the alkylation reaction and as a halide ion scavenger. Triethylamine was utilized at reflux condition of N,N-dimethylacetamide (DMA). Novel synthesized N-benzyl and N-allyl aniline derivatives (1a-f) were evaluated to be highly potent inhibitors for acetylcholinesterase (AChE) and carbonic anhydrases (hCAs). The half maximal inhibitory concentration (IC₅₀) of N-benzyl- and N-allyl aniline derivatives were calculated between 243.11 and 633.54 nM for hCA I, 296.32–518.37 nM for hCA II and 182.45–520.21 nM for AChE enzymes. On the other hand, K_i values are in the range of 149.24 ± 15.59 to 519.59 ± 102.27 nM for AChE, 202.12 ± 16.21 to 635.31 ± 45.33 nM for hCA I and 298.57 ± 94.13 to 511.18 ± 115.98 nM for hCA II isoenzyme. Additionally, in silico molecular docking computations were performed with Autodock Vina program to support the experimental in vitro studies for both hCAs and AChE inhibitors. The in silico molecular docking results demonstrated that the scores are in good agreement with the experimental results.     

Stabilization of glucose oxidase fromPenicillium vitale entrapped in high-concentration gels

Glucose ixidase fromPenicillium vitale was immobilized in a 2-hydroxyethyl methacrylate (HEMA) gel containing 0.3 to 2% of methacrylic acid (MAA) or MAA neutralized by allylamine (AA). Depending on the MAA quantity of MAA in the gel, the thermal irreversible inactivation(k _in) constants of the immobilized enzymes sharply decrease at gel concentrations higher than 29 to 50% at pH 5.8. A 220- to 250-fold decrease ofk _in was observed in 60 to 80% gel. The inactivation rate of enzyme in HEMA gel also decreases considerably under the action of urea. Over the range of pH 5.0 to 9.0 thek _in of the native enzyme depends on pH by a degree of 2.1, and of the immobilized enzyme, 0.3 to 0.55. Over the pH range of 5.2 to 5.7,k _in of the native and immobilized enzymes are approximate, whereas at pH 8 and over the difference betweenk _in values exceeds four orders of magnitude. The activity dependence of the immobilized enzyme on pH is shifted two units to the alkaline region. This shift depends on the ionic strength of the solution. This dependence is best reflected in the high gel concentrations. A mechanism of enzymes stabilization in the concentrated HEMA gel is discussed.     

Thiol‐responsive micelles based on nonionic gemini surfactants with a cystine disulfide spacer

Thiol‐responsive micelles consisting of novel nonionic gemini surfactants with a cystine disulfide spacer are reported. The gemini surfactants, (C₁₈‐Cys‐mPEG)₂ and ((C₁₈)₂‐Lys‐Cys‐mPEG)₂, were synthesized from polyethylene glycol, cysteine, and stearic acid, and their structures were confirmed by ¹H NMR and gel permeation chromatography. (C₁₈‐Cys‐mPEG)₂ and ((C₁₈)₂‐Lys‐Cys‐mPEG)₂ formed micelles with average diameters of 13 and 22 nm above the critical micelle concentration of 6.5 and 4.7 µg mL^?1, respectively. The micelles of ((C₁₈)₂‐Lys‐Cys‐mPEG)₂ containing more stearoyl groups showed encapsulated more hydrophobic indomethacin (IMC) with higher entrapment efficiencies than those of (C₁₈‐Cys‐mPEG)₂. The gemini surfactant micelles exhibited an accelerated release of encapsulated IMC with the concentration of the reducing agent, glutathione (GSH), whereas they were unaffected by the presence of reduced GSH (GSSG). The 3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)?2‐(4‐sulfophenyl)?2H‐tetrazolium studies revealed the noncytotoxic nature of the gemini surfactant micelles. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 582–589     

Hydrazones of 4-(Trifluoromethyl)benzohydrazide as New Inhibitors of Acetyl- and Butyrylcholinesterase

Based on the broad spectrum of biological activity of hydrazide–hydrazones, trifluoromethyl compounds, and clinical usage of cholinesterase inhibitors, we investigated hydrazones obtained from 4-(trifluoromethyl)benzohydrazide and various benzaldehydes or aliphatic ketones as potential inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). They were evaluated using Ellman’s spectrophotometric method. The hydrazide–hydrazones produced a dual inhibition of both cholinesterase enzymes with IC₅₀ values of 46.8–137.7 µM and 19.1–881.1 µM for AChE and BuChE, respectively. The majority of the compounds were stronger inhibitors of AChE; four of them (2-bromobenzaldehyde, 3-(trifluoromethyl)benzaldehyde, cyclohexanone, and camphor-based 2o, 2p, 3c, and 3d, respectively) produced a balanced inhibition of the enzymes and only 2-chloro/trifluoromethyl benzylidene derivatives 2d and 2q were found to be more potent inhibitors of BuChE. 4-(Trifluoromethyl)-N’-[4-(trifluoromethyl)benzylidene]benzohydrazide 2l produced the strongest inhibition of AChE via mixed-type inhibition determined experimentally. Structure–activity relationships were identified. The compounds fit physicochemical space for targeting central nervous systems with no apparent cytotoxicity for eukaryotic cell line together. The study provides new insights into this CF₃-hydrazide–hydrazone scaffold.