In vitro inhibition effect of some coumarin compounds on purified human serum paraoxonase 1 (PON1)

Evaluation of in vitro effect, molecular docking, and molecular dynamics simulations of some dihydropyridine-class calcium channel blockers on human serum paraoxonase 1 (hPON1) enzyme activity

Paraoxonase 1 (PON1) was purified 148.80-fold in 37.92% yield by hydrophobic interaction chromatography technique. The purity of PON1 was checked by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with a single band of 43 kDa. The in vitro effects of nine different calcium channel blockers on PON1 activity were evaluated. All drugs strongly decreased PON1 activity, and IC50 levels were between 13.987 ± 0.59 and 238.104 ± 2.14 μM, Ki values between 8.58 ± 0.36 and 111 ± 1.27 μM. The drugs with the strongest inhibitory effect were nisoldipine with 13.987 ± 0.59 μM and nicardipine with 20.158 ± 0.43 μM. The mechanism of action for the inhibition of the enzyme by nisoldipine and nicardipine was investigated through molecular docking. The stability of enzyme-ligand complexes obtained from the docking was explored through molecular dynamics simulation. The binding affinity of the ligands toward the enzyme was also investigated through MMPBSA (molecular mechanics Poisson-Boltzmann surface area method). The computational analysis demonstrated these compounds could inhibit the enzyme. Nisoldipine had the strongest binding, and its complex was the most stable one. Furthermore, nicardipine was found to have the highest affinity toward the enzyme.

In vitro effects of thirty-eight cardiac drugs on human serum paraoxonase

In this study, the effects of 38 commonly used cardiac drugs on the human paraoxonase (PON1) were investigated. PON1 was purified from human serum blood by ammonium sulfate precipitation (60%-80%) and hydrophobic interaction chromatography (Sepharose-4B~L-tyrosine~1-napthylamine gel). All of the cardiac drugs inhibited PON1 at the micro molar level. IC₅₀ and K_i values were determined for each drug. The tested drugs displayed potent PON1 inhibitory activity. It was found that the weakest PON1 inhibitors are Irbesartan (K_i : 421.73 µM), Glyceryl Trinitrate (K_i : 351.48 µM), and Apixaban (K_i : 333.27 µM). Bisoprolol hemifumarate (K_i : 269.31 µM) is also other weak PON1 inhibitor. Therefore, these drugs, having weak PON1 inhibitory activity, may be preferred primarily in patients with atheroclerotic heart disease compared to other drugs due to the protective effect of PON1 on atherosclerosis. Conversely, the most potent inhibitors against PON1 were propafenone (K_i : 0.35 µM), Lacidipine (K_i : 0.78 µM), Lidocaine HCl (K_i : 1.78 µM), and Propranolol (K_i : 1.86 µM). Molecular docking was also applied to confirm the activity of some cardiac drugs on PON1.

Coumarin-benzimidazole hybrids: A review of developments in medicinal chemistry

Coumarin and benzimidazole are privileged structures in medicinal chemistry and are widely used in drug discovery and development due to their vast biological properties. The pharmacokinetic and pharmacodynamic properties of the individual scaffolds can be improved by developing coumarin-benzimidazole chimeric molecules via molecular hybridization approach. The three major classes of coumarin-benzimidazole hybrids are merged, fused and spacer-linked hybrids. Depending on the substitution position, fused hybrids and spacer-linked hybrids can be further classified as coumarin-C3 hybrids, coumarin-C4 hybrids and coumarin-C5/6/7/8 hybrids. Most of the coumarin-benzimidazole hybrid molecules exhibited potent anticancer, antiviral, antimicrobial, antitubercular, anthelmintic, anti-inflammatory, antioxidant, anticonvulsant and carbonic anhydrase inhibitory activities. The fused coumarin-C3 hybrid (2), thiomethylene-linked coumarin-C3 hybrid (45), N-glucoside substituted thiomethylene-linked coumarin-C3 hybrid (37c), amide-linked coumarin-C3 hybrid (50a), and sulfonylmethylene-linked coumarin-C4 hybrid (63) were identified as the representative potent anticancer, antimicrobial, antiviral, antioxidant and antitubercular agents respectively. The biological properties of the different classes of coumarin-benzimidazole hybrids with their structure-activity relationship studies and the mechanism of action studies were presented in this review, aiming to help the researchers across the globe to generate future hybrid molecules as potential drug candidates.

Association of human serum paraoxonase-1 with some respiratory drugs

In this study, we investigated the effects of certain respiratory drugs, which are mainly used on human serum paraoxonase-1 (hPON1; EC 3.1.8.1). hPON1 was purified from human serum, with 354.91 fold and 45% yield by using two simple step procedures including, first, ammonium sulfate precipitation, then, Sepharose-4B-l-tyrosine-1-naphthylamine hydrophobic interaction chromatography. SDS-polyacrylamide gel electrophoresis showed a single protein band belonging to hPON1 with 43 kDa. All the pharmaceutical compounds inhibited the PON1 enzyme highly at the micromolar level. The obtained IC₅₀ values for nine different pharmaceutics ranged from 0.219 μM (salbutamol sulfate) to 67.205 μM (montelukast sodium). So, all drugs could be considered as potent hPON1 inhibitors. K_i values and inhibition types were determined by Lineweaver-Burk graphs. While varenicline tartrate and moxifloxacin hydrochloride inhibited the enzyme in a noncompetitive manner, others inhibited it in a mixed manner.

Relationship between internal and external factors and the activity of PON1

Paraoxonase 1 (PON1) is an A-esterase calcium-dependent enzyme that is associated with high-density lipoprotein (HDL) and capable of hydrolyzing a wide variety of substrates, including organophosphate (OP) pesticides. The PON1 phenotype can be modulated by multiple internal and external factors, thereby affecting the catalytic capacity of the enzyme. The aim of this study was to evaluate factors that could modulate PON1 activity in a sample occupationally exposed to pesticides. A cross-sectional, descriptive, and analytical study was carried out with 240 workers. The participants were stratified according to their level of pesticide exposure as reference, moderate-exposure, and high-exposure groups. PON1 activities (arylesterase/AREase, CMPAase, and ssPONase (salt-stimulated)) were determined by spectrophotometry, and the Q192R and L55MPON1 genotypes by real-time PCR. The most frequent genotypes were heterozygous (QR) and homozygous (LL) for PON1Q192R and PON1L55M polymorphisms, respectively. The internal factors associated with the activity of PON1 were the PON1 genotypes (55 and 192) and biochemical parameters related to the lipid profile, in contrast, various external factors related to diet and harmful habits as well as with exposure to pesticides were associated with the activity of PON1. However, using a multivariate mixed ordinal regression model, we found a significant reduction of ssPONase activity in the high-exposure group compared with the reference group only in haplotypes QQLL and RRLL.