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

Modulatory Effect of Lifestyle-Related, Environmental and Genetic Factors on Paraoxonase-1 Activity: A Review

Paraoxonase-1 (PON1) is a calcium-dependent, HDL-bound serum hydrolase active toward a wide variety of substrates. PON1 displays three types of activities, among which lactonase, paraoxonase, arylesterase and phosphotriesterase can be distinguished. Not only is this enzyme a major organophosphate compound detoxifier, but it is also an important constituent of the cellular antioxidant system and has anti-inflammatory and antiatherogenic functions. The concentration and activity of PON1 is highly variable among individuals, and these differences can be both of genetic origin and be a subject of epigenetic regulation. Owing to the fact that, in recent decades, the exposure of humans to an increasing number of different xenobiotics has been continuously rising, the issues concerning the role and activity of PON1 shall be reconsidered with particular attention to growing pharmaceuticals intake, dietary habits and environmental awareness. In the following manuscript, the current state of knowledge concerning the influence of certain modifiable and unmodifiable factors, including smoking, alcohol intake, gender, age and genotype variation on PON1 activity, along with pathways through which these could interfere with the enzyme's protective functions, is presented and discussed. Since exposure to certain xenobiotics plays a key role in PON1 activity, the influence of organophosphates, heavy metals and several pharmaceutical agents is also specified.

Biological evaluation and in silico study of benzohydrazide derivatives as paraoxonase 1 inhibitors

Serum paraoxonase 1 (PON1) is found in all mammalian species and is a calcium-dependent hydrolytic enzyme. PON1 hydrolyze several substrates, including carbonates, esters, and organophosphates. In the current study, we aimed to investigate the effect of the presynthesized benzohydrazide derivatives (1-9) on PON1 activity. Benzohydrazide compounds moderate inhibited PON1 with the half-maximal inhibitory concentration values ranging from 76.04 ± 13.51 to 221.70 ± 13.59 μM and K_I values ranging from 38.75 ± 12.21 to 543.50 ± 69.76 μM. Compound 4 (2-amino-4-chlorobenzohydrazide) showed the best inhibition (K_I  = 38.75 ± 12.21 μM). Molecular docking and ADME-Tox studies of benzohydrazide derivatives were also carried out. In this context, we hope that the results obtained in this study contribute to the determination of the side effects of current and new benzohydrazide-based pharmacological compounds to be developed.

Methyl benzoate derivatives: in vitro Paraoxonase 1 inhibition and in silico studies

Paraoxonase 1 (PON1) can metabolize some compounds such as aromatic carboxylic acid and unsaturated aliphatic esters, arylesters, cyclic carbonate, plucuronide drugs, some carbamate insecticide classes, nerve gases, and lactone compounds. Methyl benzoate has recently been shown to display potent toxicity against several insect species. In the current study, we aimed to investigate the effect of the methyl benzoate compounds (1-17) on PON1 activity. Methyl benzoate compounds inhibited PON1 with K_I values ranging from 25.10 ± 4.73 to 502.10 ± 64.72 μM. Compound 10 (methyl 4-amino-2-bromo benzoate) showed the best inhibition (K_I  = 25.10 ± 4.73 μM). Furthermore, using the ADME-Tox, Glide XP, and MM-GBSA tools of the Schrödinger Suite 2021-4, a complete ligand-receptor interaction prediction was performed to characterize the methyl benzoates (1-17), probable binding modalities versus the PON1.

Paraoxonase and oxidative stress changes in left and right ventricles of exhaustively exercised rats

Exhaustive exercise can cause subclinical inflammation to the heart, as it is an oxidative tissue that works continuously. The effect of exhaustive exercise on left and right ventricles (LVs, RVs) may be different. It is claimed that paraoxonase-1 (PON1), an antioxidant enzyme, has a cardioprotective effect on oxidative stress. Rats were separated as non-exercised controls (Con), those euthanized immediately after (E-0) and 24 h after exhaustive exercise (E-24). Cardiac troponin-I (cTnI), total antioxidant status (TAS), total oxidant status (TOS), PON1 activities, and histological findings in LV and RV of the exhausted rats were evaluated. TAS and PON1 levels were lower in LVs compared with RVs of all groups. TOS levels were high in LVs compared with RVs of all groups. In LVs, TAS levels decreased significantly in the E-0 group while PON1 activity decreased in E-0 and E-24 groups compared with controls. In LVs, TOS levels decreased significantly in E-0 and E-24 groups, but in RVs a decrease was seen only in the E-0 group. cTnI levels increased significantly in the E-0 group and decreased to control levels in the E-24 group. Considering the histological and biochemical findings, exhaustive exercise affected the heart to the maximum during and just after exhaustion, and LV was influenced more than RV.

Molecular Docking Studies and Inhibition Properties of Some Antineoplastic Agents against Paraoxonase-I

Background:

Currently, most of the drugs used in clinical applications show their pharmacological influences by inhibiting or activating enzymes. Therefore, enzyme inhibitors have an essential place in the drug design for many diseases.

Objective:

The current study aimed to contribute to this growing drug design field (i.e., medicine discovery and development) by analyzing enzyme-drug interactions.

Methods:

For this reason, Paraoxonase-I (PON1) enzyme was purified from fresh human serum by using rapid chromatographic techniques. Additionally, the inhibition effects of some antineoplastic agents were researched on the PON1.

Results:

The enzyme was obtained with a specific activity of 2603.57 EU/mg protein. IC50 values for pemetrexed disodium, irinotecan hydrochloride, dacarbazine, and azacitidine were determined to be 9.63μM, 30.13μM, 53.31μM, and 21.00mM, respectively. These agents found to strongly inhibit PON1, with Ki constants ranging from 8.29±1.47μM to 23.34±2.71mM. Dacarbazine and azacitidine showed non-competitive inhibition, while other drugs showed competitive inhibition. Furthermore, molecular docking was performed using maestro for these agents. Among these, irinotecan hydrochloride and pemetrexed disodium possess the binding energy of -5.46 and -8.43 kcal/mol, respectively.

Conclusion:

The interaction studies indicated that these agents with the PON1 possess binding affinity.

Paraoxonase-1: Characteristics and Role in Atherosclerosis and Carotid Artery Disease

Paraoxonase-1 (PON-1) is a calcium-dependent enzyme that is synthesized in the liver and then secreted in blood where it is bound to high density lipoprotein (HDL). PON-1 is a hydrolase with a wide range of substrates, including lipid peroxides. It is considered responsible for many of the antiatherogenic properties of HDL. PON-1 prevents low density lipoprotein (LDL) oxidation, a process that is considered to contribute to the initiation and development of atherosclerosis. PON-1 activity and levels are influenced by gene polymorphisms; of the 2 common variants, one is in position 192 (Q192R) and one in position 55 (M55L). Also, many drugs affect PON-1 activity. The role of PON-1 in carotid atherosclerosis is inconsistent. Some studies show an association of PON-1 polymorphisms with carotid plaque formation, whereas others do not. The aim of this review is to summarize the characteristics of PON-1, its interactions with drugs and its role in atherosclerosis and especially its relationship with carotid artery disease.

Benzenesulfonamide derivatives containing imine and amine groups: Inhibition on human paraoxonase and molecular docking studies

Sulfonamides known as inhibitors of many metabolic enzymes have been widely used as antimicrobial drugs for a long time. In the present study, we investigated in vitro inhibitory activities of benzenesulfonamide derivatives on human paraoxonase-I (hPON1). For this aim, PON1 was purified from human serum with a specific activity of 2603.57 EU/mg and 8.34% yield using simple chromatographic methods. The various concentrations of early-synthesized sixteen sulfonamide derivatives were tested on the paraoxonase activity. Ki values of compounds were found in the range of 0.28-357.70 µM. Compound H4 had the highest inhibitory activity on hPON1 as competitive. Estimated structure-activity relationship (SAR) for compounds was done based on different substituents and their positions in the compounds. Besides, the molecular docking analysis of compound H4 was performed to understand the binding interactions on the active site of the enzyme. According to these experimental results, compound H4 was a potential inhibitor of PON1.

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 K_i 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.

Differential effects of selective serotonin reuptake inhibitors on paraoxonase-1 enzyme activity: An in vitro study

Paraoxonase-I (PON1) is a calcium-dependent hydrolytic enzyme, plays an important role in most antioxidant properties related to high-density lipoprotein (HDL). Antidepressant drugs are commonly employed in treatment of mood disorders and anxiety treatment. In this study, human serum PON1 was purified using simple reproducible procedures and the effects of some antidepressant drugs on its activity were determined. It was found that mirtazapine, aripiprazole, escitalopram, and risperidone exhibited potential inhibitory properties on the purified PON1 activity with IC₅₀ values in the range of 115.50-231.00 μM and K_i values in the range of 41.66 ± 4.27 μM-276.36 ± 35.28 μM. Both risperidone and escitalopram inhibited PON1 activity competitively, while both aripiprazole and mirtazapine inhibited PON1 activity non-competitively. Chlorpromazine did not affect PON1 activity. Usage of drugs with significant biological activity may be hazardous in some cases.

Investigation of Potential Paraoxonase-I Inhibitors by Kinetic and Molecular Docking Studies: Chemotherapeutic Drugs

BACKGROUND

Metabolic processes in living organisms are closely related to the catalytic activity of enzymes. Changes in enzyme activity cause various diseases e.g., neurological, cancer, metabolic and cardiovascular. Most of the current therapeutic drugs available in clinical utilization function as enzyme inhibitors.

OBJECTIVE

The main goal of the current study to contribute to this growing drug design area (such as medication discovery and development) by investigating protein-drug interactions.

METHODS

The paraoxonase-I (PON1) enzyme was purified from human serum by using different and simple chromatographic techniques. Additionally, it was investigated inhibition effects of some chemotherapeutic drugs on the PON1.

RESULTS

The purification results for PON1 depicted a 3880.83 EU/mg proteins specific activity and the molecular weight was calculated as 43 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These drugs found to strongly inhibit PON1, with IC50 values ranging from 0.222±0.002 to 688.300±0.897 µM. Ki constants for vincristine sulfate, epirubicin hydrochloride, and doxorubicin hydrochloride were determined to be 0.235±0.032 µM, 221.400±29.270 µM, and 913.300±201.000 µM, respectively.

CONCLUSION

These drugs showed in competitive inhibition. Also, the molecular docking poses of these agents inside the catalytic sites of 1V04 and 3SRE were analysis.

A potential risk factor for paraoxonase 1: in silico and in-vitro analysis of the biological activity of proton-pump inhibitors†

Objectives

Proton-pump inhibitors (PPIs) are drugs commonly utilized by about 7% of adults in the world. Recent researches have shown that there are countless and severe side effects of these drugs. This situation has raised concern among clinicians and patients alike. The purpose of this study is to contribute the novel drug discovery and development technology and toxicology field by researching interactions of PPIs on paraoxonase 1.

Methods

In this study, the paraoxonase 1 enzyme was purified from human serum by using rapid and straightforward chromatographic techniques. Subsequently, the inhibition effects of pantoprazole, omeprazole, and esomeprazole, PPIs, were investigated on paraoxonase 1. Besides, molecular docking studies were performed to unravel the binding mechanism between the enzyme and drugs.

Key findings

All drugs showed potent inhibitory activities. IC50 of the drugs values were 54.780 ± 0.524, 86.470 ± 0.818 and 93.390 ± 0.885 mm and Ki constants were found as 39.895 ± 0.005 mm, 70.112 ± 0.010 mm and 78.868 ± 0.008 mm, respectively. The binding scores observed in silico studies were found to agree with the obtained from in-vitro experimental results.

Conclusions

We observed that the drugs decreased PON1 activity at low concentrations. The results show that adjusting the dosages of these medications is a crucial case for each patient. The physicians should more carefully interpret whether there is an essential indication before prescribing PPIs and, if there is, to approve the proper dosing for the situation.

The behaviour of some antihypertension drugs on human serum paraoxonase-1: an important protector enzyme against atherosclerosis

Objectives

Paraoxonase-1 (PON1) enzyme is related to high-density lipoprotein (HDL), which is calcium dependent. It has essential roles such as protecting LDL against oxidation and detoxification of highly toxic substances. It is a significant risk to reduce the levels of this enzyme in patients with diabetes mellitus, cardiovascular diseases, hyperthyroidism and chronic renal failure.

Methods

Here, it was reported that the purification of human serum PON1 using straightforward methods and determination of the interactions between some antihypertension drugs and the enzyme.

Key finding

It was found that these drugs exhibit potential inhibitor properties for human serum PON1 with IC50 values in the range of 131.40–369.40 μm and Ki values in the range of 56.24 ± 6.75–286.74 ± 28.28 μm. These drugs showed different inhibition mechanisms. It was determined that midodrine and nadolol were exhibited competitive inhibition, but atenolol and pindolol were exhibited non-competitive inhibition.

Conclusion

Usage of these drugs would be hazardous in some cases.

Investigation of Potential Paraoxonase-I Inhibitors by Kinetic and Molecular Docking Studies: Chemotherapeutic Drugs

Background:

Metabolic processes in living organisms are closely related to the catalytic activity of enzymes. Changes in enzyme activity cause various diseases e.g., neurological, cancer, metabolic and cardiovascular. Most of the current therapeutic drugs available in clinical utilization function as enzyme inhibitors.

Objective:

The main goal of the current study to contribute to this growing drug design area (such as medication discovery and development) by investigating protein-drug interactions.

Methods:

The paraoxonase-I (PON1) enzyme was purified from human serum by using different and simple chromatographic techniques. Additionally, it was investigated inhibition effects of some chemotherapeutic drugs on the PON1.

Results:

The purification results for PON1 depicted a 3880.83 EU/mg proteins specific activity and the molecular weight was calculated as 43 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These drugs found to strongly inhibit PON1, with IC50 values ranging from 0.222±0.002 to 688.300±0.897 µM. Ki constants for vincristine sulfate, epirubicin hydrochloride, and doxorubicin hydrochloride were determined to be 0.235±0.032 µM, 221.400±29.270 µM, and 913.300±201.000 µM, respectively.

Conclusion:

These drugs showed in competitive inhibition. Also, the molecular docking poses of these agents inside the catalytic sites of 1V04 and 3SRE were analysis.

Gadolinium-based contrast agents: in vitro paraoxonase 1 inhibition, in silico studies

Medications show their biological effects by interaction with enzymes, which have been known to play an essential role in the pathogenesis of many diseases. Inhibition or induction of drug metabolizing enzymes has an essential place in the drug design for many kinds of diseases including cardiovascular, neurological, metabolic, and cancer. The main goal of the current study is to contribute to this growing drug design field by observing PON1-drug interactions. In recent years, the safety of gadolinium-based contrast agents (GBCAs) used in magnetic resonance imaging (MRI) has discussed. In the present study, paraoxonase 1 (PON1) enzyme was purified from human serum by simple chromatographic methods with 4095.24 EU mg^-1 protein specific activity. The inhibitory activities of gadoteric acid, gadopentetic acid, gadoxetate disodium, and gadodiamide were investigated on PON1 activity of the enzyme. IC₅₀ values were found in the range of 51.28 ± 0.14 to 285.80 ± 0.96 mM. K_i constants were found as 67.95 ± 0.60 mM, 104.97 ± 0.96 mM, 202.33 ± 1.75 mM, and 299.43 ± 2.64 mM for gadoteric acid, gadopentetic acid, gadoxetate disodium, and gadodiamide, respectively. While the inhibition types are determined as competitive of gadoxetate disodium and gadodiamide by the Lineweaver-Burk curves, it was noncompetitive for other compounds. In addition, the molecular docking analyses of gadoxetate disodium and gadodiamide were carried out to understand the binding interactions on the active site of the PON1 enzyme. The structure-activity relationship (SAR) of the drugs was established on the basis of different substituents and their positions in the compounds.

Inhibitory Effects of Usnic and Carnosic Acid on Some Metabolic Enzymes: An In vitro Study

Background:

Natural products are produced via primary and secondary metabolism in different organisms. The compounds obtained via secondary metabolism are not essential for the survival of the organism, but they can have a different value for humans.

Objective:

The objective of this study was to examine inhibitory effects of Usnic Acid (UA), a well-known lichen secondary metabolite, and Carnosic Acid (CA), the primary antioxidant compound of Rosmarinus officinalis L., on purified Human Paraoxonase, (PON1), Glutathione Reductase (GR) and Glutathione S-Transferase (GST). These enzymes have antioxidant properties and a protective effect on the oxidation of free radicals. Hence, deficiencies of such enzymes inside cells can result in a buildup of toxic substances and cause some metabolic disorders.

Methods:

UA and CA were tested in various concentrations against human GST, PON1, and GR activity in vitro and they reduced human GST, PON1, and GR activity.

Results:

UA Ki constants were calculated as 0.012±0.0019, 0.107±0.06 and 0.21±0.1 mM for GST, PON1, and GR enzymes. CA Ki constants were determined as 0.028±0.009, 0.094±0.03 and 0.79±0.33 mM, for GST, PON1, and GR enzymes. UA and CA showed competitive inhibition for GR and GST enzymes, while they exhibited non-competitive inhibition for PON1.

Conclusion:

These findings indicate that UA and CA could be useful in drug development studies.

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.

The role of paraoxonase in cancer

The paraoxonase (PON) gene family includes three proteins, PON1, PON2 and PON3. PON1 and PON3 are both associated with high-density lipoprotein (HDL) particles and exert anti-oxidant and anti-inflammatory properties. PON2 and PON3 are intracellular enzymes which modulate mitochondrial superoxide anion production and endoplasmic reticulum (ER) stress-induced apoptosis. The pleiotropic roles exerted by PONs have been mainly investigated in cardiovascular and neurodegenerative diseases. In recent years, overexpression of PON2 and PON3 has been observed in cancer cells and it has been proposed that both enzymes could be involved in tumor survival and stress resistance. Moreover, a lower activity of serum PON1 has been reported in cancer patients. This review summarizes literature data on the role of PONs in human cancers and their potential role as a target for antitumor drugs.

An alternative purification method for human serum paraoxonase 1 and its interaction with methidathion

In this study, an alternative purification method for human Paraoxonase 1 (hPON1) enzyme was developed using two-step procedures, namely ammonium sulphate precipitation and Sepharose-4B-L-tyrosine-1-aminoanthracene hydrophobic interaction chromatography. SDS-polyacrylamide gel electrophoresis of the enzyme indicates a single band with an apparent MW of 43 kDa. The enzyme was purified 674-fold with a yield of 16%. Furthermore, we examined the in vitro effect of methidathion on the enzyme activity to understand the better inhibitory properties of the compound. Methidathion is a highly toxic insecticide used to control a broad spectrum of agricultural insect and mite pests. IC₅₀ value was found to be 0.130 mM for the pesticide. Methidathion showed a competitive inhibition with Ki of 0.119 mM for paraoxon.