Preferential inhibition of paraoxonase activity of human paraoxonase 1 by negatively charged lipids

Capsaicin Exerts Anti-convulsant and Neuroprotective Effects in Pentylenetetrazole-Induced Seizures

The transient receptor potential vanilloid-1 (TRPV1) receptor has been implicated in the development of epileptic seizures. We examined the effect of the TRPV1 agonist capsaicin on epileptic seizures, neuronal injury and oxidative stress in a model of status epilepticus induced in the rat by intraperitoneal (i.p.) injections of pentylenetetrazole (PTZ). Capsaicin was i.p. given at 1 or 2 mg/kg, 30 min before the first PTZ injection. Other groups were i.p. treated with the vehicle or the anti-epileptic drug phenytoin (30 mg/kg) alone or co-administered with capsaicin at 2 mg/kg. Brain levels of malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide, and paraoxonase-1 (PON-1) activity, seizure scores, latency time and PTZ dose required to reach status epilepticus were determined. Histopathological assessment of neuronal damage was done. Results showed that brain MDA decreased by treatment with capsaicin, phenytoin or capsaicin/phenytoin. Nitric oxide decreased by capsaicin or capsaicin/phenytoin. GSH and PON-1 activity increased after capsaicin, phenytoin or capsaicin/phenytoin. Mean total seizure score decreased by 48.8% and 66.3% by capsaicin compared with 78.7% for phenytoin and 69.8% for capsaicin/phenytoin treatment. Only phenytoin increased the latency (115.7%) and threshold dose of PTZ (78.3%). Capsaicin did not decrease the anti-convulsive effect of phenytoin but prevented the phenytoin-induced increase in latency time and threshold dose. Neuronal damage decreased by phenytoin or capsaicin at 2 mg/kg but almost completely prevented by capsaicin/phenytoin. Thus in this model of status epilepticus, capsaicin decreased brain oxidative stress, the severity of seizures and neuronal injury and its co-administration with phenytoin afforded neuronal protection.

Bougainvillea spectabilis flowers extract protects against the rotenone-induced toxicity

OBJECTIVE

To investigate the effect of two extracts of Bougainvillea spectabilis (B. spectabilis) flowers with yellow and pink/purple on brain oxidative stress and neuronal damage caused in rats by systemic rotenone injection.

METHODS

Rotenone 1.5 mg/kg was given three times per week alone or in combination with B. spectabilis flowers extracts (25 mg or 50 mg) via the subcutaneous route for 2 weeks. Brain concentrations of the lipid peroxidation marker malondialdehyde (MDA), reduced glutathione, nitric oxide (nitrite), the pro-inflammatory cytokine interleukin-1beta (Il-1β) as well as butyrylcholinesterase, and paraoxonase-1 (PON-1) activities, were determined. Histopathology and caspase-3 immunohistochemistry were also performed.

RESULTS

Rotenone resulted in significant increases of brain MDA (the product of lipid peroxidation), and nitric oxide content along with decreased brain reduced glutathione. There were also marked and significant inhibition of brain PON-1 and BChE activities and increased Il-1β in brain of rotenone-treated rats. B. spectabilis flowers extract itself resulted in brain oxidative stress increasing both lipid peroxidation and nitrite content whilst inhibiting PON-1 activity. The yellow flowers extract inhibited BChE activity and increased brain Il-1β. When given to rotenone-treated rats, B. spectabilis extracts, however, decreased lipid peroxidation while their low administered doses increased brain GSH. Brain nitrite decreased by the pink extract but showed further increase by the yellow extract. Either extract, however, caused further inhibition of PON-1 activity while the yellow extract resulted in further inhibition of BChE activity. Histopathological studies indicated that both extracts protected against brain, liver and kidney damage caused by the toxicant.

CONCLUSIONS

These data indicate that B. spectabilis flowers extracts exert protective effect against the toxic effects of rotenone on brain, liver and kidney. B. spectabilis flowers extracts decreased brain lipid peroxidation and prevented neuronal death due to rotenone and might thus prove the value in treatment of Parkinson's disease.

Paraoxonases function as unique protectors against cardiovascular diseases and diabetes: Updated experimental and clinical data

Paraoxonase (PON) refers to a family of three enzymes, namely PON1, PON2, and PON3. PON1 and PON3 are found in circulation bound to high-density lipoprotein, whereas PON2 is an intracellular protein. PON1 was first discovered as an enzyme to hydrolyze the organophosphate pesticide paraoxon, an activity that both PON2 and PON3 lack. All three PON enzymes are able to degrade oxidized lipids and protect against oxidative stress. PON enzymes also act to suppress inflammation. Animal studies show a critical role for PON enzymes, especially PON1 in protecting against cardiovascular diseases and related disorders, including diabetes and metabolic syndrome. In line with the findings in experimental animals, accumulating evidence from clinical research also indicates that PON enzymes function as potential protectors in human cardiovascular diseases and related disorders. Identification of PON enzymes as important players in cardiovascular health will facilitate the development of novel preventive and therapeutic modalities targeting PON enzymes to combat cardiovascular diseases and related disorders, which collectively constitute the chief contributors to the global burden of disease. This review describes the biochemical properties and molecular regulation of PON and summarizes the major recent findings on the functions of PON in protecting against cardiovascular diseases and related disorders.

Dietary fatty acid intake is associated with paraoxonase 1 activity in a cohort-based analysis of 1,548 subjects

BACKGROUND

Paraoxonase 1 (PON1) is a cardioprotective, HDL-associated glycoprotein enzyme with broad substrate specificity. Our previous work found associations between dietary cholesterol and vitamin C with PON1 activity. The goal of this study was to determine the effect of specific dietary fatty acid (DFA) intake on PON1 activity.

METHODS

1,548 participants with paraoxonase activity measures completed the Harvard Standardized Food Frequency Questionnaire to determine their daily nutrient intake over the past year. Eight saturated, 3 monounsaturated, and 6 polyunsaturated DFAs were measured by the questionnaire. To reduce the number of observations tested, only specific fatty acids that were not highly correlated (r < 0.8) with other DFAs or that were representative of other DFAs through high correlation within each respective group (saturated, monounsaturated, or polyunsaturated) were retained for analysis. Six specific DFA intakes - myristic acid (14 carbon atoms, no double bonds - 14:0), oleic acid (18:1), gadoleic acid (20:1), α-linolenic acid (18:3), arachidonic acid (20:4), and eicosapentaenoic acid (20:5) - were carried forward to stepwise linear regression, which evaluated the effect of each specific DFA on covariate-adjusted PON1 enzyme activity.

RESULTS

Four of the 6 tested DFA intakes - myristic acid (p = 0.038), gadoleic acid (p = 6.68 × 10(-7)), arachidonic acid (p = 0.0007), and eicosapentaenoic acid (p = 0.013) - were independently associated with covariate-adjusted PON1 enzyme activity. Myristic acid, a saturated fat, and gadoleic acid, a monounsaturated fat, were both positively associated with PON1 activity. Both of the tested polyunsaturated fats, arachidonic acid and eicosapentaenoic acid, were negatively associated with PON1 activity.

CONCLUSIONS

This study presents the largest cohort-based analysis of the relationship between dietary lipids and PON1 enzyme activity. Further research is necessary to elucidate and understand the specific biological mechanisms, whether direct or regulatory, through which DFAs affect PON1 activity.

Interactions between negative energy balance, metabolic diseases, uterine health and immune response in transition dairy cows

The biological cycles of milk production and reproduction determine dairying profitability thus making management decisions dynamic and time-dependent. Diseases also negatively impact on net earnings of a dairy enterprise. Transition cows in particular face the challenge of negative energy balance (NEB) and/or disproportional energy metabolism (fatty liver, ketosis, subacute, acute ruminal acidosis); disturbed mineral utilization (milk fever, sub-clinical hypocalcemia); and perturbed immune function (retained placenta, metritis, mastitis). Consequently NEB and reduced dry matter intake are aggravated. The combined effects of all these challenges are reduced fertility and milk production resulting in diminishing profits. Risk factors such as NEB, inflammation and impairment of the immune response are highly cause-and-effect related. Thus, managing cows during the transition period should be geared toward reducing NEB or feeding specially formulated diets to improve immunity. Given that all cows experience a reduced feed intake and body condition, infection and inflammation of the uterus after calving, there is a need for further research on the immunology of transition dairy cows. Integrative approaches at the molecular, cellular and animal level may unravel the complex interactions between disturbed metabolism and immune function that predispose cows to periparturient diseases.

Dietary fats and health: dietary recommendations in the context of scientific evidence

Although early studies showed that saturated fat diets with very low levels of PUFAs increase serum cholesterol, whereas other studies showed high serum cholesterol increased the risk of coronary artery disease (CAD), the evidence of dietary saturated fats increasing CAD or causing premature death was weak. Over the years, data revealed that dietary saturated fatty acids (SFAs) are not associated with CAD and other adverse health effects or at worst are weakly associated in some analyses when other contributing factors may be overlooked. Several recent analyses indicate that SFAs, particularly in dairy products and coconut oil, can improve health. The evidence of ω6 polyunsaturated fatty acids (PUFAs) promoting inflammation and augmenting many diseases continues to grow, whereas ω3 PUFAs seem to counter these adverse effects. The replacement of saturated fats in the diet with carbohydrates, especially sugars, has resulted in increased obesity and its associated health complications. Well-established mechanisms have been proposed for the adverse health effects of some alternative or replacement nutrients, such as simple carbohydrates and PUFAs. The focus on dietary manipulation of serum cholesterol may be moot in view of numerous other factors that increase the risk of heart disease. The adverse health effects that have been associated with saturated fats in the past are most likely due to factors other than SFAs, which are discussed here. This review calls for a rational reevaluation of existing dietary recommendations that focus on minimizing dietary SFAs, for which mechanisms for adverse health effects are lacking.

Paraoxonases: ancient substrate hunters and their evolving role in ischemic heart disease

Interest in the role of paraoxonases (PON) in cardiovascular research has increased substantially over the past two decades. These multifaceted and pleiotropic enzymes are encoded by three highly conserved genes (PON1, PON2, and PON3) located on chromosome 7q21.3-22.1. Phylogenetic analysis suggests that PON2 is the ancient gene from which PON1 and PON3 arose via gene duplication. Although PON are primarily lactonases with overlapping, but distinct specificities, their physiologic substrates remain poorly characterized. The most interesting characteristic of PON, however, is their multifunctional roles in various biochemical pathways. These include protection against oxidative damage and lipid peroxidation, contribution to innate immunity, detoxification of reactive molecules, bioactivation of drugs, modulation of endoplasmic reticulum stress, and regulation of cell proliferation/apoptosis. In general, PON appear as "hunters" of old and new substrates often involved in athero- and thrombogenesis. Although reduced PON activity appears associated with increased cardiovascular risk, the correlation between PON genotype and ischemic heart disease remains controversial. In this review, we examine the biochemical pathways impacted by these unique enzymes and investigate the potential use of PON as diagnostic tools and their impact on development of future therapeutic strategies.

Oxidative stress and autonomic nervous system functions in restless legs syndrome

BACKGROUND

Oxidative stress has been implicated in over 100 disorders in recent years; however, the situation in restless legs syndrome (RLS) has not been studied yet.

METHODS

Fifty patients with RLS not medicated for RLS and 50 sex- and age-matched, healthy controls and controls with no pathology except mild iron deficiency or iron deficiency anaemia were enrolled. Patients with secondary RLS other than iron deficiency were excluded. Total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), arylesterase (ARE), paraoxonase (PON), stimulated paraoxonase (stim-PON), lipid hydroperoxides (LOOHs), acetyl cholinesterase (AChE) and butyryl cholinesterase (BuChE) were measured. Heart rate variability (HRV) analysis was performed.

RESULTS

TOS, ARE and AChE were increased (P = 0·018, P < 0·001 and P < 0·001, respectively), whereas LOOHs were decreased (P < 0·001) in RLS group. TAS, OSI, PON and stim-PON were comparable. Erythrocyte sedimentation rate (ESR) and mean platelet volume (MPV) were increased (P = 0·021 and P = 0·037, respectively) in RLS group. HRV triangular index (HRVi) was lower (P = 0·012) in RLS group. Other HRV parameters were similar.

CONCLUSIONS

Increased AChE and decreased LOOHs, which were influenced by increased PON1, were considered as indicators of efforts towards the protection of dopaminergic activity in central nervous system in RLS group. Increased ESR, MPV and low HRVi indicate elevated sympathetic activity in RLS group. Elevated sympathetic activity might be beneficial in relieving RLS symptoms, also causing increases in TOS. The evidence we found regarding oxidative stress and autonomic nervous system might be seminal in RLS treatment.

Human carotid lesion linoleic acid hydroperoxide inhibits paraoxonase 1 (PON1) activity via reaction with PON1 free sulfhydryl cysteine 284

Paraoxonase 1 (PON1) is an HDL-associated lactonase with antiatherogenic properties. These include dampening the oxidation properties of human carotid lesion lipid extract (LLE), which in turn inactivates the enzyme. The aims of this study were to identify the PON1 inhibitor in LLE and explore the mechanism of inhibition. LLE inhibited both recombinant PON1 and HDL-PON1 lactonase activity in a dose- and time-dependent manner. Addition of antioxidants or electrophiles to LLE did not prevent PON1 inhibition. LLE was unable to inhibit a PON1 mutant lacking Cys284, whereas it did inhibit all other PON1 mutants tested. The inhibitor in the LLE was identified as linoleic acid hydroperoxide (LA-OOH) and inhibition was specific to this hydroperoxide. During its inhibition, PON1 acted like a peroxidase enzyme, reducing LA-OOH to LA-hydroxide via its Cys284. A similar reaction occurred with external thiols, such as DDT or cysteine, which also prevented PON1 inhibition and restored enzyme activity after inhibition. Thus, the antiatherogenic properties of HDL could be, at least in part, related to the sulfhydryl-reducing characteristics of its associated PON1, which are further protected and recycled by the sulfhydryl amino acid cysteine.

Pharmacological and dietary modulators of paraoxonase 1 (PON1) activity and expression: the hunt goes on

Paraoxonase 1 (PON1) is a high density lipoprotein (HDL)-associated enzyme displaying esterase and lactonase activity. PON1 hydrolyzes several organophosphorus (OP) insecticides and nerve agents, a number of exogenous and endogenous lactones, and metabolizes toxic oxidized lipids of low density lipoproteins (LDL) and HDL. As such, PON1 plays a relevant role in determining susceptibility to OP toxicity, cardiovascular diseases and several other diseases. Serum PON1 activity in a given population can vary by at least 40-fold. Most of this variation can be accounted for by genetic polymorphisms in the coding region (Q192R, L55M) and in the promoter region (T-108C). However, exogenous factors may also modulate PON1 activity and/or level of expression. This paper examines various factors that have been found to positively modulate PON1. Certain drugs (e.g. hypolipemic and anti-diabetic compounds), dietary factors (antioxidants, polyphenols), and life-style factors (moderate alcohol consumption) appear to increase PON1 activity. Given the relevance of PON1 in protecting from certain environmental exposure and from cardiovascular and other diseases, there is a need for further mechanistic, animal, and clinical research in this area, and for consideration of possible alternative strategies for increasing the levels and activity of PON1.

Broad-spectrum antioxidant peptides derived from His residue-containing sequences present in human paraoxonase 1

Hydroxyl or peroxyl radicals and hypochlorous acid (HOCl) are known to cause the oxidation of lipoproteins. Here, we examined Cu(2+)-binding property of paraoxonase 1 (PON1), and antioxidant actions of peptides, resembling His residue-containing sequences in PON1, against oxidations by Cu(2+), peroxyl radicals or HOCl. When Cu(2+)-binding property of PON1 was examined spectrophotometrically, the maximal Cu(2+) binding was achieved at 1:1 molar ratio of PON1: Cu(2+). Additionally, Cu(2+)-catalyzed oxidative inactivation of PON1 was prevented by Ca(2+)-depleted PON1 at 1:1 ratio, but not diethylpyrocarbonate (DEPC)-modified PON1, suggesting the participation of His residue in Cu(2+)-binding. When His-containing peptides were examined for antioxidant actions, those with either His residue at N-terminal position 2 or 3, or His-Pro sequence at C-terminal remarkably prevented Cu(2+)-mediated low density lipoprotein (LDL) oxidation and PON1 inactivation. Especially, FHKALY, FHKY or NHP efficiently prevented Cu(2+)-induced LDL oxidation (24 h), indicating a tight binding of Cu(2+) by peptides. In support of this, the peptide/Cu(2+) complexes exhibited a superoxide-scavenging activity. Separately, in oxidations by 2,2'-azobis-2-amidinopropane hydrochloride or HOCl, the presence of Tyrosine (Tyr) or Cysteine (Cys) residue markedly enhanced antioxidant action of His-containing peptides. These results indicate that His-containing peptides with Tys or Cys residues correspond to broad spectrum antioxidants in oxidation models employing Cu(2+), 2,2'-azobis-2-amidinopropane hydrochloride (AAPH) or HOCl.

Oxidation–reduction potential and paraoxonase–arylesterase activity in trauma patients

The amount of oxidative stress in severely traumatized patients is usually based on various individual parameters such as total antioxidants and lipid peroxidation. Serial measurements of plasma oxidation-reduction potential (ORP) in severely traumatized patients as a simple mean of assessing overall oxidative stress is described. Serial whole blood samples were obtained from multi-trauma patients (N=39) and healthy individuals (N=10). Plasma ORP in multi-trauma patients increased during the first few days of hospitalization and approached normal ORP levels upon discharge. On the ORP maxima day (5.8 days+/-0.5 SEM), a statistically significant decrease (p<0.05) was observed for negative acute phase reactants such as plasma paraoxonase-arylesterase (PON-AE) activity and total plasma protein in comparison with admission plasma levels. Monitoring ORP could be a useful tool for assessing the degree of oxidative stress, inflammation, severity of injury, and potential efficacy of treatment.

Paraoxonase 1 response to a high-fat diet: gender differences in the factors involved

Diets consumed in industrialized countries are rich in fat and increase the incidence of atherosclerosis, a process reported to be influenced by gender. Considering the anti-atherogenic role attributed to serum Paraoxonase 1 (PON1) activity, and given the pro-atherogenic effects described for saturated fatty acids (SFA), as opposed to the beneficial ones conferred to monounsaturated fatty acids (MUFA), the aim of this study was to investigate the response of male and female rat serum PON1 activity and its related factors to a high-fat (HF), hypercaloric diet (fat representing 55.2% of the energy) containing similar amounts of SFA and MUFA. The HF diet feeding did not alter total body weight, but increased adiposity. Nevertheless, and in spite of the increased adiposity, the HF diet did not entail a more pro-inflammatory serum adipokine or lipid profile or increased lipid peroxidation. Paraoxonase activity was reduced in both male and female HF fed rats, due to a reduction of PON1 mRNA levels in males and to a reduced stability and/or number of HDL particles responsible for PON1 transport in females. Both the maintenance of body weight and the MUFA content in the diet would be among the factors responsible for the attenuation of the negative effects usually related to excessive fat intake and for the reduction in PON activity, whose antioxidant activity would be less necessary in this situation.

Severe systemic immune response syndrome, low plasma paraoxonase activity, and a new albumin species in a traumatized patient with Gaucher's disease

INTRODUCTION

Gaucher's disease (GD) is an inborn error, autosomal recessive lysosomal lipid storage disorder characterized by the lack of the enzyme glucocerebrosidase. We observed some abnormalities in the plasma of a traumatized patient with GD.

CASE REPORT

We report of a traumatized patient with GD that developed a severe systemic immune response during the course of an extended hospital stay. Plasma paraoxonase (PON) activity was assayed and found to be extremely low possibly due to the existence of GD in this particular patient. Also, a potentially novel post-translational modification (PTM) of albumin was noticed in the patient's plasma that coincided with enzyme replacement therapy (ERT) with Cerezyme.

CONCLUSIONS

The decreased plasma PON activity measured might be a contributive factor in the development of an accentuated systemic immune response in a traumatized patient with GD. A modified albumin species could serve as a biomarker for ERT in Gaucher patients.

Differential effect of lysophospholipids on activities of human plasma paraoxonase1, either soluble or lipid-bound

Interaction of paraoxonase1 (PON1) with lysophospholipids was examined with respect to activity regulation and binding property. Paraoxonase activity of purified PON1 was partially inhibited by palmitoyl-lysophosphatidyl-glycerol (palmitoyl-lysoPG) and lysophosphatidylinositol (lysoPI), which had a stimulatory effect on arylesterase and diazoxonase activities. The selective inhibition of paraoxonase activity by palmitoyl-lysoPG, characterized by noncompetitiveness and charge interaction, was also observed with HDL- or dimyristoylphosphatidylcholine (DMPC)-bound PON1. Meanwhile, lysophosphatidylcholine (lysoPC) stimulated all three activities of purified PON1, although it stimulated DMPC-bound or HDL-bound PON1 to a lesser extent. The stimulatory action of lysophospholipids was observed around their CMC, suggesting that micelle formation of lysophospholpids might be involved in the stimulation of PON1 activity. Presumably in support of this, the tryptophan fluorescence intensity of PON1 was increased by lysophospholipids at concentrations required for the stimulation of PON1 activity. Separately, lysoPC stimulation was less remarkable for DMPC-bound PON1 than for either dimyristoylphosphatidylserine (DMPS)- or dimyristoylphosphatidylglycerol-bound PON1, suggesting a tight association between PON1 and DMPC. In support of this, the stimulatory role of apolipoprotein A-I was less prominent for DMPC-bound PON1 than for DMPS-bound PON1. Taken together, these data suggest that the inhibition of paraoxonase activity by lysoPG or lysoPI may be due to binding to a site distinct from the active center, whereas the stimulation by lysophospholipid may be ascribed to the micelle formation around the lipid-associable region of PON1.

Preferable stimulation of PON1 arylesterase activity by phosphatidylcholines with unsaturated acyl chains or oxidized acyl chains at sn-2 position

To examine the effect of phospholipids on PON1 activities, purified PON1 was exposed to phospholipids prior to the determination of arylesterase and paraoxonase activities. Phosphatidylcholines with saturated acyl chains (C10-C16) showed a stimulation of both activities, chain length-dependent, with a greater stimulation of arylesterase activity, suggesting the implication of lipid bilayer in the stimulatory action. Such a preferable stimulation of arylesterase activity was more remarkable with phosphatidylcholines with polyunsaturated acyl chains or oxidized chains at sn-2 position, implying that the packing degree of acyl chain may be also important for the preferable stimulation of arylesterase activity. Separately, 1-palmitoyl-lysoPC also stimulated arylesterase activity preferably, indicating that the micellar formation of lipids around PON1 also contributes to the stimulatory action. Additionally, phosphatidylglycerols slightly enhanced arylesterase activity, but not paraoxonase activity. In contrast, phosphatidylserine and phosphatidic acid (> or =0.1 mM) inhibited both activities Further, such a preferable stimulation of arylesterase activity by phosphatidylcholines was also reproduced with VLDL-bound PON1, although to a less extent. These data indicate that phosphatidylcholines with polyunsaturated acyl chains or oxidized chain, or lysophosphatidylcholine cause a preferable stimulation of arylesterase activity, thereby contributing to the decrease in the ratio of paraoxonase activity to arylesterase activity.

Paraoxonases and cardiovascular diseases: pharmacological and nutritional influences

PURPOSE OF REVIEW

To summarize the new articles published in the last year on paraoxonases, including their expression in cardiovascular diseases, and regulation by pharmacological and nutritional means.

RECENT FINDINGS

The elucidation of the crystal structure of the paraoxonase 1 (PON1) gene, obtained by directed evolution, shows that it consists of a six-bladed beta-propeller with a unique active site. PON1 is present in HDL but also in lipoprotein-deficient serum, in VLDL and in chylomicrons. PON1 protects lipids in lipoproteins, in macrophages and in erythrocytes from oxidation. Cellular PON2 and PON3 were also shown to reduce oxidative stress. Beyond its antioxidative properties, PON1 possesses additional antiatherogenic properties against macrophage foam cell formation: attenuation of cholesterol and oxidized lipids influx, inhibition of macrophage cholesterol biosynthesis and stimulation of macrophage cholesterol efflux. The PON1 gene is regulated by Sp1 and protein kinase C, whereas the PON2 gene in macrophages is regulated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. PON1 activity and mass are both reduced in cardiovascular diseases and the hypocholesterolemic drugs, statins, increase serum PON1 activity (by reducing oxidative stress, or by upregulating hepatic PON1 expression). Expression of cellular PON2, like PON1, was upregulated by statins. Nutritional antioxidants, such as polyphenols, increase PON1 mRNA expression and activity, by an aryl hydrocarbon receptor-dependent mechanism.

SUMMARY

The elucidation of PON1 structure and its active center has enabled a better understanding of its mechanism of action, including its physio-pathological substrate(s). Some drugs and nutrients including dietary antioxidants and polyphenols considerably increase the activities of paraoxonases which, in turn, can reduce oxidative stress and atherosclerosis development.