Exploring New 5-Nitroimidazole Derivatives As Potent Acetylcholinesterase and Butyrylcholinesterase Enzyme Inhibitors.

Discovering new compounds capable of inhibiting physiologically and metabolically significant drug targets or enzymes is of paramount importance in biological chemistry. With this aim, new 5-nitroimidazole derivatives (1-4) were designed and synthesized, and their inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) were discovered using acetyl (butyryl) thiocholine and Ellman's reagents for spectrophotometric assay. The inhibitory profiles of the synthesized compounds were assessed by comparing their IC50 and Ki values. Results demonstrate significant inhibitory activity of all synthesized compounds against both AChE and BuChE compared to the reference compound, donepezil. Notably, compound 4 exhibited dual inhibition of these enzymes, showing the highest activity against Electrophorus electricus AChE (EeAChE) with a Ki value of 0.024±0.009 nM and against equine BuChE (eqBuChE) with a Ki value of 0.087±0.017 nM. Furthermore, molecular modeling was conducted to study the interaction modes of the most potent compound (4) and donepezil in the active site of their related enzymes' crystal structures (PDB ID: 4EY7 and 4BDS, respectively). Additionally, drug-likeness, ADME, and toxicity profiles of the compounds and metronidazole were predicted. The above results indicated that the dual inhibition of these enzymes is considered as a promising strategy for the treatment of neurological disorder especially Alzheimer's disease.

Enzyme inhibitory potential of some indole Schiff bases on acetylcholinesterase and human carbonic anhydrase isoforms I and II enzymes: an in vitro and molecular docking study.

In this study, the in vitro effects of some indole Schiff bases on acetylcholinesterase and human carbonic anhydrase isoforms I and II were investigated. A series of N-methylindole hydrazide/hydrazone derivatives (1a-1t) were tested on these enzymes. The interactions of the synthesized indole derivatives with target enzymes were studied by molecular docking methodology. The results revealed that indole derivative Schiff base compounds inhibited the enzymes significantly. Ki values for hCAI isoenzyme were determined to be in the range of 36.18 ± 3.07-224.29 ± 5.78 nM; for the hCAII isoenzyme in the range of 31.30 ± 2.63-201.64 ± 7.25 nM; for acetylcholinesterase in the range of 6.82 ± 0.72-110.30 ± 9.26 nM. Compared to the control compound Acetazolamide (AZA), 1k and 1p were found to have the best inhibitory effect for hCAI; 1p was found to be the best inhibitory effect for hCAII. Compared to the control compound Tacrine (TAC), 1s showed the best inhibitory effect for AChE. In vitro results were verified with the results obtained by docking studies and interactions with enzymes were demonstrated.Communicated by Ramaswamy H. Sarma.

Relationship between zinc content and carbonic anhydrase activity in blood of anemic pregnant women in Turkey.

AIMS: Carbonic anhydrase (CA) in pregnancy plays an important part in gaseous exchange across the placenta. The aim of our study was to determine the relationship between zinc content and the CA activity in blood of anemic and normal pregnant women in their third trimester, in Turkey. METHODS: The patients with hemoglobin values below 11 g/dL were accepted as anemic. CA enzyme activity and zinc levels in erythrocyte of anemic and non-anemic pregnant women were carried out in 27 non-anemic pregnant women and 31 anemic pregnant women. Mean corpuscular volume (MCV) levels of the participants were also tested. RESULTS: Zinc levels were lower in the anemic group compared to the non-anemic group (P = 0.049). Total CA enzyme activity was also lower in the anemic group (P = 0.044). MCV levels were found to be lower in the anemic group (P = 0.007). The decrease in these values was statistically significant (P < 0.05). CONCLUSION: This is the first study to evaluate the zinc content in red blood cells of anemic pregnant women in the third trimester and its relationship with carbonic anhydrase activity. CA isoenzymes to work healthily, providing iron and zinc supports is important for fetal development.

Synthesis, characterization, and in vitro effect of the Cu(II) complex with niflumic acid and 3-picoline on paraoxanase-I.

Niflumic acid is used to treat inflammatory rheumatoid diseases, pain, and fever. The present study reports the experimental, spectroscopic, thermal, structural analyses, and biological activities of this complex. The nonsteroidal anti-inflammatory drug niflumic acid, 3-picoline, and copper(II) chloride were utilized to synthesize a new complex: [Cu2 Cl 2 (nif) 2 (3-pic) 4 ]. The crystal structure of [Cu 2 Cl 2 (nif) 2 (3-pic) 4 ] was determined by X-ray crystallography. The complex crystallizes in the triclinic space group P-1 and each Cu(II) center displayed six-coordinated distorted octahedral geometry. Two Cu(II) centers are connected by a chloro-bridge to form the binuclear metal core. Finally, the in vitro effects of the synthesized new complex and free niflumic acid were evaluated on the human serum paraoxonase 1 enzyme. At low doses, both the new complex and free niflumic acid showed very good inhibition activity with different inhibition mechanisms. In addition, the results showed that the new complex has more inhibition activity than free niflumic acid.

Antibiotics Used in Patients after Surgery and Effects of Human Serum Paraoxonase-I (PON1) Enzyme Activity.

BACKGROUND: Paraoxonase (PON; arilesterase, [EC 3.1.8.1]) is an enzyme from the group arilesterases (ARE). This enzyme is capable of hydrolyzing paraoxone which is the active metabolite of parathion, an organic phosphorus insecticide. PON activity was found to be low in individuals prone to development of atherosclerosis such as diabetes, familial hypercholesterolemia and kidney disorders. It was noted that PON enzyme activity decreases in relation to age increase in adults. PON enzyme activity is approximately half of that in newborns and premature babies. Approximately one year after birth, it reaches the adult level. It can be said that PON1 has significant role on living organisms. For this reason, many studies on interactions of PON-drugs are needed. OBJECTIVE: In this article, our aim is to investigate in vitro effects of four pharmaceutically active agents (fosfomycin, cefuroxime axetil, cefaclor monohydrate, and cefixime) which are often used in patients after surgery on human serum paraoxanase-I (PON1) enzyme activity. METHODS: In this article, we purify paraoxonase-I enzyme from human serum by using ammonium sulfate precipitation (in the range of 60-80%), ion exchange and gel filtration chromatography. We use electrophoresis to check the purity of the enzyme. We investigate the paraoxonase activity of the enzyme at 412 nm the inhibition effects of the active substances. Paraoxone is used as the substrate. Activity measurements arw made at different inhibitor concentrations related to inhibitor studies and % Activity- [I] graphs are drawn for drug active substances. Lineweaver-Burk graphics are used to determine the Ki constants. Finally, to determine the types of inhibition we interpret these graphs. RESULTS: The active agents used after surgery decreased the PON1 enzyme activity. They showed different inhibition mechanism. The inhibition mechanism of fosfomycin and cefaclor monohydrate was noncompetitive, cefixime was uncompetitive and cefuroxime axetil was a competitive inhibitor. The IC50 values for fosfomycin, cefuroxime axetil, cefaclor monohydrate, and cefixime were calculated to be 31.5 mM, 1.03 mM, 4.18 mM and 0.781 mM, respectively, and the Ki constants were determined to be 27.98 ± 12.25 mM, 2.20 ± 0.22 mM, 4.81 ± 2.25 mM and 1.12 ± 0.32 mM, respectively. The IC50 and Ki values showed that cefixime active agent has the maximum inhibition. CONCLUSION: In this study, we have detected that cefuroxime axetil inhibited competitively in vitro paraoxonase activity of this enzyme. According to this information, we thought that cefuroxime axetil linked to the active site of the enzyme. Fosfomycin and cefaclor monohydrate can be attached with amino acids out of the active site of the enzyme because they inhibit enzyme noncompetitively. Cefixime can be attached only to the enzyme-substrate complex because it inhibits enzyme uncompetitively.

Synthesis and characterization of four novel palladium(II) and platinum(II) complexes with 1-(2-aminoethyl)pyrrolidine, diclofenac and mefenamic acid: In vitro effect of these complexes on human serum paraoxanase1 activity.

In this study, the effects of four novel mononuclear palladium(II) and platinum(II) complexes on the activity of human serum paraoxanase1 were examined. First, four novel mononuclear palladium(II) and platinum(II) complexes were synthesized with a nitrogen donor ligand 1-(2-aminoethyl)pyrrolidine and nonsteroidal anti-inflammatory drugs diclofenac, mefenamic acid. These complexes were characterized by spectroscopic, thermal, and elemental analyses. The crystal structures of complex [Pd(2-amepyr)2 ](dicl)2 1 and [Pd(2-amepyr)2 ](mef)2 3 were determined by X-ray crystallography. Then, paraoxonase1 enzyme was purified from human serum. The effects of these complexes on enzyme were evaluated in vitro. The complexes consist of the cationic unit and the counterions. The diclofenac and mefenamic acid acted as a counterion in the complexes. It was observed that all the complexes were stable up to high temperatures. These complexes, even at low doses, inhibited the activity of the enzyme with different inhibition mechanisms.

Natural product inhibitors of carbonic anhydrase I and II isoenzymes: osajin and pomiferin.

The aim of this study is to purify carbonic anhydrase I and II isoenzymes from human erythrocyte, isolate two natural products osajin (OSJ) and pomiferin (PMF) from Maclura pomifera fruits, and evaluate the in vitro effect of these natural metabolites on these isoenzymes. These natural products may be used as starting points for drug discovery (like drugs used in several therapeutic applications, including antiglaucoma activity). For the purification procedure, the Sepharose-4B-l-tyrosine-sulphonamide affinity chromatography was used. Column chromatography and thin layer chromatography methods were used for isolation of OSJ and PMF from M. pomifera fruits and their chemical structures were elucidated by IR, 1D, and 2D NMR methods. We compared inhibitory effects of these natural products with inhibitory effects of phenolic compounds and found that these products demonstrated average inhibition effects. We thought that this study will give inspiration to scientists interested in this issue.

Activation of Two Different Drugs Used in Alzheimer's Disease Treatment on Human Carbonic Anhydrase Isozymes I and II Activity: an In Vitro Study.

OBJECTIVES: Human carbonic anhydrase I and II (hCAI, II) isoenzymes were purified from human erythrocyte. Kinetic interactions between the enzymes and memantine and donepezil, two different drugs used in Alzheimer's disease (AD) treatment, were investigated. MATERIALS AND METHODS: The purification procedure was composed of preparation of homogenate (or hemolysate) and affinity chromatography on Sepharose 4B-L-tyrosine-sulfanilamide. RESULTS: Both drug exhibited in vitro activator effects on hCAI and II enzymes activity. Strong activations were found for these compounds: The CA values of memantine and donepezil against hCAI were 0.013 µM and 1.8 µM, respectively. The KA values of memantine and donepezil against hCAII were 0.045 µM and 3.7 µM, respectively. CONCLUSION: Since the levels of CA isoenzymes are low in patients with AD or in the older population, increasing activities of these isoenzymes are important for these patients. The effect of these drugs used in AD treatment was thought to be caused by positive changes in the levels of carbonic anhydrase isoenzymes.

Synthesis of two phloroglucinol derivatives with cinnamyl moieties as inhibitors of the carbonic anhydrase isozymes I and II: an in vitro study.

Two cinnamyl-substituted phloroglucinols, 4-p-methoxycinnamyl phloroglucinol (9) and 4,6-bis-p-methoxycinnamyl phloroglucinol (10) were synthesized. Two carbonic anhydrases, human carbonic anhydrase I and II (hCA I and II), were purified. Kinetic interactions between these isozymes with 9 and 10 were investigated. These new compounds exhibited inhibitory effects on the hCA I and II enzymes' activity in vitro. The combination of the inhibitory effects of both phloroglucinol and p-coumaric acid groups in a single compound was explored. However, relative to the inhibitory effects of the two groups separately, compounds 9 and 10 demonstrated comparable inhibitory effects. More effective inhibitors of CAs could be created by testing these compounds on other CA isozymes.

In Vitro Inhibition Of Three Different Drugs Used In Rheumatoid Arthritis Treatment On Human Serum Paraoxanase 1 Enzyme Activity.

We studied in vitro effects of three different drugs (ibuprofen, meloxicam and methotrexate) which are often used in rheumatoid arthritis (RA) treatment on human serum paraoxanase1 (PON1) enzyme activity. The drugs used in RA treatment decreased the in vitro PON1 activity. The inhibition mechanism of ibuprofen and methotrexate were noncompetitive whereas meloxicam was a competitive inhibitor. The IC50 values for ibuprofen, meloxicam and methotrexate were calculated to be 0.35 mM, 0.10 mM, and 0.18 mM, respectively, and the Ki constants were calculated to be 0.890 mM, 0.125 mM, and 0.260 mM, respectively. The IC50 and Ki values showed the maximum inhibition of meloxicam drugs. We propose a prediction scheme for the interaction of meloxicam with the PON1 active site because we thought that meloxicam interacts with the amino acids which are in the PON1 enzyme active site. The results we found showed that these drugs which are often used in RA treatment in vitro inhibit the activity of the enzyme with different inhibition mechanisms at low doses.

Impacts of some antibiotics on human serum paraoxonase 1 activity.

Some enzymes are known to be drug target inhibitions of which can be critical for organisms. PON has a critical role to prevent atherogenesis by inhibiting lipid peroxidation. It is well known that paraoxonase 1 (PON1) plays an important function on high-density lipoprotein (HDL) structure to prevent lipid oxidation not only of low-density lipoprotein, but also of HDL itself. We investigated in vitro effects of some medical drugs on PON1 activity from human serum. Ki constants for oxytetracycline hydrochloride, netilmycin sulfate, lincomycin hydrochloride, clindamycin phosphate, and streptomycin sulfate were found as 0.2, 3.73, 18.30, 35.80, and 56.30 mM, respectively. Our results indicate that these commonly used drugs inhibit the activity of the enzyme at very low doses with different inhibition mechanisms.