Influence of Chirality of Benzimidazole Amine Hybrids on Inhibition of Human Erythrocytes Carbonic Anhydrase I, II and Acetylcholinesterase.

Novel chiral benzimidazole amine hybrids (4a-4d) were synthesized from commercially available amine [(R)- (+)-phenylethylamine, (-) (S)-(-)-phenylethylamine, (-) (R)-(-)-cyclohexylethylamine, (S)-(+)-cyclohexylethylamine] and 2-(chloromethyl)-N-tosyl-1H-benzimidazole. The synthesized compounds (4a-4d) were characterized by IR, NMR, and LC/MS analysis. The inhibitory effect of 4a-4d on human erythrocytes carbonic anhydrase I (hCA-I), II (hCA-II), and acetylcholinesterase (AChE) activity was investigated. For hCA-I, the IC50 values of 4a-4d were found to be 4.895 µM, 1.750 µM, 0.173 µM, and 0.620 µM, respectively, and for hCA-II, the IC50 values of 4a-4d were found to be 0.469 µM, 0.380 µM, 0.233 µM, 0.635 µM, respectively. Furthermore, IC50 values of 4a-4d on AChE were found as 87.5 nM, 100 nM, 26.92 nM, and 100 nM, respectively. In addition, molecular docking analysis was performed to evaluate the affinity of 4a-4d against hCA-I, hCA-II, and AChE and explain their binding interactions.

Some indazoles as alternative inhibitors for potato polyphenol oxidase.

Fresh-cut vegetables and fruits have gained attention among consumers because of their fresh appearance, lack of pollution, nutrition, and convenience. However, in fresh-cut foods, enzymatic browning is the main problem. Polyphenol oxidase (PPO) is a vital enzyme involved in the process of enzymatic browning. In this study, PPO was purified from potato using Sepharose 4B-l-tyrosine-p-aminobenzoic acid affinity chromatography and the effect of some indazoles on the enzyme was determined. The enzyme was purified with a specific activity of 52,857.14 EU/mg protein and 21.26-purification fold. Indazoles exhibited inhibitor properties for PPO with IC50 values in the range of 0.11-1.12 mM and Ki values in the range of 0.15 ± 0.04-3.55 ± 0.88 mM. Among these compounds, 7-chloro-1H-indazole was shown as the most potent PPO inhibitor (Ki : 0.15 ± 0.04 mM). Determination of the enzyme's inhibition kinetics will simplify the testing of candidate PPO inhibitors.

Evaluation of some thiophene-based sulfonamides as potent inhibitors of carbonic anhydrase I and II isoenzymes isolated from human erythrocytes by kinetic and molecular modelling studies.

BACKGROUND: Thiophene(s) are an important group in therapeutic applications, and sulfonamides are the most important class of carbonic anhydrase (CA) inhibitors. In this study, inhibition effects of some thiophene-based sulfonamides on human erythrocytes carbonic anhydrase I and II isoenzymes (hCA-I and hCA-II) were investigated. Thiophene-based sulfonamides used in this study showed potent inhibition effect on both isoenzymes at very small concentrations. MATERIALS AND METHODS: We report on the purification of the carbonic anhydrase I and II isoenzymes (hCA-I and hCA-II) using affinity chromatography method. The inhibition effect of the thiophene-based sulfonamides was determined by IC50 and Ki parameters. A molecular docking study was performed for each molecule. RESULTS: Thiophene-based sulfonamides showed IC50 values of in the range of 69 nM to 70 µM against hCA-I, 23.4 nM to 1.405 µM against hCA-II. Ki values were in the range of 66.49 ± 17.15 nM to 234.99 ± 15.44 µM against hCA-I, 74.88 ± 20.65 nM to 38.04 ± 12.97 µM against hCA-II. Thiophene-based sulfonamides studied in this research showed noncompetitive inhibitory properties on both isoenzymes. To elucidate the mechanism of inhibition, a molecular docking study was performed for molecules 1 and 4 exhibiting a strong inhibitory effect on hCA-I and hCA-II. The compounds inhibit the enzymes by interacting out of catalytic active site. The sulfonamide and thiophene moiety played a significant role in the inhibition of the enzymes. CONCLUSION: We hope that this study will contribute to the design of novel thiophene-based sulfonamide derived therapeutic agents that may be carbonic anhydrase inhibitors in inhibitor design studies.

Lactoperoxidase, an antimicrobial enzyme, is inhibited by some indazoles.

Lactoperoxidase (LPO) has bactericidal and bacteriostatic activity on various microorganisms and it creates a natural antimicrobial defense system. So, LPO is one of the essential enzyme in biological systems and the protection of the LPO activity is extremely important for the immune system. Because of these features, the protection of the activity of the LPO has vital importance for the health of the organisms. Also, LPO is used in various sectors from cosmetics industry to agriculture industry due to its broad antimicrobial properties. Therefore, the identification of inhibitors and activators of the LPO is becoming increasingly important. In present study we aimed to investigate the inhibitory effects of some indazoles [1H-indazole (1a), 4-Bromo-1H-indazole (2a), 6-Bromo-1H-indazole (3a), 7-Bromo-1H-indazole (4a), 4-chloro-1H-indazole (5a), 6-chloro-1H-indazole (6a), 7-chloro-1H-indazole (7a), 4-fluoro-1H-indazole (8a), 6-fluoro-1H-indazole (9a), 7-fluoro-1H-indazole (10a)] on bovine milk LPO. Indazole derivatives are heterocyclic organic molecules with a wide range of biological activity. For this aim, bovine milk LPO was purified using Sepharose-4B-l-tyrosine-5-amino-2-methyl benzenesulfonamide affinity chromatography method. Then, the potential inhibitory effects of indazoles on LPO activity were investigated. Ki values were calculated for each indazole molecule. Ki values were ranging from 4.10 to 252.78 µM for 1a to10a. All of the indazole molecules we studied showed strong inhibitory effect on LPO activity. Also we determined inhibition types of the indazoles to clarify the mechanisms of inhibition.

Purification of Polyphenol Oxidase from Potato and Investigation of the Inhibitory Effects of Phenolic Acids on Enzyme Activity.

BACKGROUND: Polyphenol Oxidase (PPO) belongs to the oxidoreductase enzyme family. METHODS: Here, PPO was purified from potato using Sepharose 4B-L-tyrosine-p-aminobenzoic acid affinity chromatography. It determined the interactions between some phenolic acids and the enzyme. RESULTS: The enzyme was obtained with a specific activity of 15333.33 EU/mg protein and 7.87- fold purification. It was found that phenolic acids exhibited inhibitory properties for PPO. The IC50 values of the phenolic acids were found in the range of 0.36-2.12 mM, and their Ki values were found in the range of 0.28± 0.07-1.72±0.32 mM. It was determined that all studied compounds displayed a competitive inhibition effect. Among these compounds, 3-hydroxybenzoic acid was found to be the most effective PPO inhibitor (Ki: 0.28±0.07 mM). CONCLUSION: Investigating the inhibition kinetics of the enzyme will simplify the testing of PPO inhibitor candidates.

Investigation of the effects of some sulfonamides on acetylcholinesterase and carbonic anhydrase enzymes.

Human carbonic anhydrase I and II isoenzymes (hCA I and II) and acetylcholinesterase (AChE) are important metabolic enzymes that are closely associated with various physiological and pathological processes. In this study, we investigated the inhibition effects of some sulfonamides on hCA I, hCA II, and AChE enzymes. Both hCA isoenzymes were purified by Sepharose-4B-L-Tyrosine-5-amino-2-methylbenzenesulfonamide affinity column chromatography with 1393.44 and 1223.09-folds, respectively. Also, some inhibition parameters including IC50 and Ki values were determined. Sulfonamide compounds showed IC 50 values of in the range of 55.14 to 562.62 nM against hCA I, 55.99 to 261.96 nM against hCA II, and 98.65 to 283.31 nM against AChE. Ki values were in the range of 23.40 ± 9.10 to 365.35 ± 24.42 nM against hCA I, 45.87 ± 5.04 to 230.08 ± 92.23 nM against hCA II, and 16.00 ± 45.53 to 157.00 ± 4.02 nM against AChE. As a result, sulfonamides had potent inhibition effects on these enzymes. Therefore, we believe that these results may contribute to the development of new drugs particularly in the treatment of some disorders.

Some indazoles reduced the activity of human serum paraoxonase 1, an antioxidant enzyme: in vitro inhibition and molecular modeling studies.

Background: Paraoxonase 1 (PON1: EC 3.1.8.1) is a vital antioxidant enzyme against mainly atherosclerosis and many other diseases associated with oxidative stress. Thus, studies related to PON1 have an important place in the pharmacology. In this study, we aimed to evaluate the in vitro inhibition effects of some indazoles on the activity of human PON1. Methods: PON1 was purified from human serum with a specific activity of 5000 U/mg and 13.50% yield by using simple chromatographic methods. Results: The indazoles showed Ki values in a range of 26.0 ± 3.00-111 ± 31.0 µM against hPON1. All these indazoles exhibited competitive inhibition. In addition, molecular docking studies were performed in order to assess the probable binding mechanisms into the active site of hPON1. Molecular modeling studies confirmed our results. Conclusions: Inhibition of PON1 by indazoles supplies a verification to further consideration of limitation dosage of indazole molecule groups as drug.

1H-indazole molecules reduced the activity of human erythrocytes carbonic anhydrase I and II isoenzymes.

Carbonic anhydrase (CA) is an important metabolic enzyme family closely related to many physiological and pathological processes. Currently, carbonic anhydrase inhibitors are the target molecules in the treatment and diagnosis of many diseases. In present study, we investigated the inhibitory effects of some indazole molecules on the CA-I and CA-II isoenzymes isolated from human erythrocytes. We showed that human CA-I and CA-II activities were reduced by of some indazoles at low concentrations. IC50 values, Ki constants, and inhibition types for each indazole molecule were determined. The indazoles showed Ki constants in a range of 0.383 ± 0.021 to 2.317 ± 0.644 mM, 0.409 ± 0.083 to 3.030 ± 0.711 mM against CA-I and CA-II, respectively. Each indazole molecule exhibited a noncompetitive inhibition effect. Bromine- and chlorine-bonded indazoles were found to be more potent inhibitory effects on carbonic anhydrase isoenzymes. In conclusion, we conclude that these results may be useful in the synthesis of carbonic anhydrase inhibitors.

Assessment of the inhibitory effects and molecular docking of some sulfonamides on human serum paraoxonase 1.

Paraoxonase-1 (PON1) is an organophosphate hydrolyzer and antiatherogenic enzyme. Due to the PON1's crucial functions, inhibitors and activators of PON1 must be known for pharmacological applications. In this study, we investigated the in vitro effects of some sulfonamides compounds on human serum PON1 (hPON1). For this aim, we purified the hPON1 from human serum with high specific activity by using simple chromatographic methods, and after the purification processes, we investigated in vitro interactions between the enzyme and some sulfonamides (2-amino-5-methyl-1,3-benzenedisulfonamide, 2-chloro-4-sülfamoilaniline, 4-amino-3-methylbenzenesulfanilamide, sulfisoxazole, sulfisomidine, and 5-amino-2-methylbenzenesulfonamide). IC50 , Ki values, and inhibition types were calculated for each sulfonamide. 2-amino-5-methyl-1,3-benzenedisulfonamide and 2-chloro-4-sülfamoilaniline exhibited noncompetitive inhibition effect, whereas 4-amino-3-methylbenzenesulfanilamide, sulfisoxazole, and sulfisomidine exhibited mixed type inhibition. On the other hand, 5-amino-2-methylbenzenesulfonamide showed competitive inhibition and so molecular docking studies were performed for this compound in order to assess the probable binding mechanism into the active site of hPON1.

Mechanism of capsaicin inhibition of aldose reductase activity.

Aldose reductase (AR) inhibitors play a vital importance as a potential therapeutic and preventive medicine when it comes to hyperglycemia associated diabetic complications. Additionally, capsaicin is used as a food additive and a drug in a number of diverse clinical trials. The aim of this study is to determine the in vitro inhibition behavior of capsaicin on AR enzyme activity, which was obtained from different rat tissues (heart, kidney, liver, and brain). We showed that AR was inhibited by capsaicin in the micromolar range and noncompetitive manner in all of the tissues. Ki values of capsaicin were found to be 8.87, 264, 535, and 597, respectively, in heart AR, kidney AR, liver AR, and brain AR. In conclusion, capsaicin may be an effective molecule when used in low concentrations to prevent diabetic complications associated with the polyol pathway.

Inhibition behaviours of some phenolic acids on rat kidney aldose reductase enzyme: an in vitro study.

Aldose reductase (AR) inhibitors have vital importance in the treatment and prevention of diabetic complications. In this study, rat kidney AR was purified 19.34-fold with a yield of 3.49% and a specific activity of 0.88 U/mg using DE-52 Cellulose anion exchange chromatography, gel filtration chromatography and 2'5' ADP Sepharose-4B affinity chromatography, respectively. After purification, the in vitro inhibition effects of some phenolic acids (tannic acid, chlorogenic acid, sinapic acid, protocatechuic acid, 4-hydroxybenzoic acid, p-coumaric acid, ferulic acid, vanillic acid, syringic acid, α-resorcylic acid, 3-hydroxybenzoic acid and gallic acid) were investigated on purified enzyme. We determined IC50, Ki values and inhibition types of these phenolic acids. As a result, tannic and chlorogenic acid had a strong inhibition effect. On the other hand, gallic acid had a weak inhibition effect. In this study, all phenolic acids except for chlorogenic acid and p-coumaric acid showed non-competitive inhibition effects on rat kidney AR.

The synthesis of novel pyrazole-3,4-dicarboxamides bearing 5-amino-1,3,4-thiadiazole-2-sulfonamide moiety with effective inhibitory activity against the isoforms of human cytosolic carbonic anhydrase I and II.

A series of 1-(3-substituted-phenyl)-5-phenyl-N(3),N(4)-bis(5-sulfamoyl-1,3,4-thiadiazol-2-yl)-1H-pyrazole-3,4-dicarboxamides (4-15) were synthesized. The structures of these pyrazole-sulfonamides were confirmed by FT-IR, (1)H NMR, (13)C NMR and elemental analysis methods. Human cytosolic carbonic anhydrase (CA, EC 4.2.1.1) isozymes (hCA I and II) were purified from erythrocyte cells by affinity chromatography. The inhibitory effects of newly synthesized derivatives (4-15) were investigated in vitro on esterase activities of these isozymes. The Ki values were determined as 0.119-3.999µM for hCA I and 0.084-0.878µM for hCA II. The results showed that the compound 6 for hCA I and the compound 11 for hCA II had the highest inhibitory effect. Beside that, the compound 8 had the lowest inhibition effect on both isozymes.

Potent Inhibitory Effects of Some Phenolic Acids on Lactoperoxidase.

Lactoperoxidase (LPO) plays a key role in immune response against pathogens. In this study, we examined the effects of some phenolic acids on LPO. For this purpose, bovine milk LPO was purified 380.85-fold with a specific activity of 26.66 EU/mg and overall yield of 73.33% by using Amberlite CG-50 H+ resin and CNBr-activated Sepharose-4B-l-tyrosine-sulfanilamide affinity chromatography. After purification, the in vitro effects of phenolic acids (tannic acid, 3,4-dihydroxybenzoic acid, 3,5- dihydroxybenzoic acid, chlorogenic acid, sinapic acid, 4-hydroxybenzoic acid, vanillic acid, salicylic acid, and 3-hydroxybenzoic acid) were investigated on LPO. These phenolic acids showed potent inhibitory effect on LPO. Ki values for these phenolic acids were found as 0.0129 nM, 0.132 µM, 0.225 µM, 0.286 µM, 0.333 µM, 2.33 µM, 10.82 µM, 0.076 mM, and 0.405 mM, respectively. Sinapic acid and 4-hydroxybenzoic acid exhibited noncompetitive inhibition; 3,4-dihydroxybenzoic acid showed uncompetitive inhibition, and other phenolic acids showed competitive inhibition.

Some Anticancer Agents Act on Human Serum Paraoxonase-1 to Reduce Its Activity.

Human serum paraoxonase (hPON1) is an important antioxidant enzyme. It protects low-density lipoproteins against oxidative stress and prevents atherosclerosis development. Anticancer agents have cardiotoxic effects, and this situation can lead to significant complications. Our aim was to evaluate the in vitro effects of some of the anticancer agents such as cetuximab, paclitaxel, etoposide, docetaxel, and ifosfamide on the activity of hPON1 in this study. For this reason, PON1 was purified from human serum with a specific activity of 3654.2 EU/mg and 16.84% yield using simple chromatographic methods. The five chemotherapeutic agents dose dependently decreased in vitro hPON1 activity. IC50 values for cetuximab, paclitaxel, etoposide, docetaxel, and ifosfamide were 0.0111, 0.042, 0.226, 0.665, and 23.3 mm, respectively. Ki constants were 0.0194, 0.0165, 0.131, 0.291, and 8.973 mm, respectively. The inhibition mechanisms of cetuximab, etoposide, docetaxel, and ifosfamide were non-competitive, and for paclitaxel was competitive. Consequently, inhibition of hPON1 by these anticancer agents may explain some of the cardiotoxic actions of these drugs.

Some Anti-Inflammatory Agents Inhibit Esterase Activities of Human Carbonic Anhydrase Isoforms I and II: An In Vitro Study.

Carbonic anhydrases (CAs) are known as a drug-target enzymes. The inhibitors of the enzyme are important compounds for discovering new therapeutic agents and understanding in detail protein-drug interactions at the molecular level. For this purpose, the in vitro effects of some anti-inflammatory agents such as tenoxicam, fluorometholone acetate, and dexamethasone were investigated on esterase activity of human erythrocyte CA-I and CA-II in this study. hCA-I and hCA-II were purified by affinity chromatography with a yield of 47.25% and 87%, and a specific activity of 642.8 EU/mg proteins and 5576.9 EU/mg proteins, respectively. SDS-PAGE was performed to determine the purity of the enzymes. Inhibitory effects of the drugs on hCA-I and hCA-II were determined by spectrophotometric method. IC50 values for hCA-I and hCA-II were 0.198, 2.18, 11.7, 0.11, 17.5 and 14 µm using tenoxicam, fluorometholone acetate, and dexamethasone, respectively. For fluorometholone acetate and dexamethasone, Ki values from Lineweaver-Burk plots were obtained as 1.044 and 21.2 µm (noncompetitive) for hCA-I and 9.98 and 8.66 µm (non-competitive) for hCA-II. In conclusion, tenoxicam, fluorometholone acetate, and dexamethasone showed potent inhibitory effects on esterase activity of hCA-I and hCA-II isozymes under in vitro conditions.

Inhibitory effect of novel pyrazole carboxamide derivatives on human carbonic anhydrase enzyme.

The synthesis, characterization and biological evaluation of novel pyrazole carboxamide derivatives (2-9) are presented. (1)H and (13)C NMR have been used for the structure description, possible tautomeric structures determination and hydrogen bonding observation. FT-IR results have confirmed the synthesis of the pyrazole derivatives while thermal gravimetric analysis has confirmed thermal stability up to 300°C. The melting temperatures are strongly dependent on their crystal structure as confirmed by differential scanning calorimetry and X-ray diffraction measurements. Impacts of 2-9 as possible antiglaucoma agents were investigated on carbonic anhydrase I and II (CA-I and II) isozymes purified from human erythrocytes in vitro. Compounds 3 and 9 had the highest inhibitory effect while compounds 6 and 8 showed the lowest inhibition.

Facile synthesis and characterization of novel pyrazole-sulfonamides and their inhibition effects on human carbonic anhydrase isoenzymes.

In the current study, a series of pyrazole-sulfonamide derivatives (2-14) were synthesized, characterized, and the inhibition effects of the derivatives on human carbonic anhydrases (hCA I and hCA II) were investigated as in vitro. Structures of these sulfonamides were confirmed by FT-IR, (1)H NMR, (13)C NMR and LC-MS analysis. (1)H NMR and (13)C NMR revealed the tautomeric structures. hCA I and hCA II isozymes were purified from human erythrocytes and inhibitory effects of newly synthesized sulfonamides on esterase activities of these isoenzymes have been studied. The K(i) values of compounds were 0.062-1.278 µM for hCA I and 0.012-0.379 µM for hCA II. The inhibition effects of 7 for hCA I and 4 for hCA II isozymes were almost in nanomolar concentration range.

Effects of some anti-neoplastic drugs on sheep liver sorbitol dehydrogenase.

Stress is an important factor for many diseases in living metabolisms. The mini pathway named as polyol is a critical junction for stress factors. This pathway has two enzymes: aldose reductase (AR) and sorbitol dehydrogenase (SDH). It is linked with some diseases such as diabetes mellitus and some cancer types. In particular, SDH is very sensitive and unstable in in vitro conditions. In this study, SDH was purified by using simple and rapid chromatographic methods such as DEAE-Sephadex and CM-Sephadex C-50 columns. Subunit and active form molecular weights were found as 39.8 kDa and 150 kDa, respectively. The in vitro effects of some antineoplastic drugs were investigated. IC(50) values were 0.025, 0.081, 0.291, 1.62, 4.86, 6.54 mM for dacarbazine, methotrexate, epirubicin hydrochloride, calcium folinate, gemcitabine hydrochloride, oxaliplatin, respectively. From these results, dacarbazine was lowest IC(50) value and it is the strongest inhibitor for liver SDH enzyme activity compared to the other drugs.

Some drugs inhibit in vitro hydratase and esterase activities of human carbonic anhydrase-I and II.

In this study, we determined the in vitro inhibitory effects of ceftriaxone sodium, imipenem and ornidazole on hydratase and esterase activities of human erythrocyte carbonic anhydrase-I and II isozymes (CA I and II). Human erythrocyte CAI and II isozymes were purified by Sepharose-4B L-tyrosine affinity chromatography column with a yield of 30% and 40%, a specific activity of 920 and 8,000 EU/mg protein, respectively. In the overall purification procedure, human carbonic anhydrase (hCA)-I and (hCA)-II were purified 104 and 900-fold, respectively. In order to determine the purity of the enzymes, SDS-PAGE was performed. Inhibitory effects of the drugs on hCA-I and hCA-II were determined by using colorimetric method for CO2-hydratase activity assay and spectrophotometric method for esterase activity assay. P-Nitrophenyl acetate was used as a substrate in the spectrophotometric esterase activity assay. The obtained IC50 values (inhibitor concentrations which cause 50% inhibition of in vitro enzyme activity) for esterase activity were 1.900, 0.008, 0.318 mM for hCA-I and 2.542, 0.0258, 0.343 mM for hCA-II for ceftriaxone sodium, imipenem and ornidazole, respectively. IC50 values for CO2-hydratase activity were 0.864, 0.00354, 0.131 mM for hCA-I and 1.118, 0.0214, 0.263 mM for hCA-II for ceftriaxone sodium, imipenem and ornidazole, respectively. In conclusion, ceftriaxone sodium, imipenem and ornidazole showed inhibitory effects on human erythrocte carbonic anhydrase-I and II isozyme activities under in vitro conditions.