[Proficiency Testing Schemes for Food Nutrition Analysis in Japan (2017-2018)].

This paper deals with proficiency testing schemes for food nutrition analysis in Japan. In schemes in 2017 and 2018, 65 and 73 organizations participated, respectively, and more than 70% of the participants were public organizations responsible for a nutrition-labeling compliance test. The food matrices were pork and chicken sausages, and analytes were protein, fat, ash, moisture, carbohydrate, energy, sodium, salt equivalent, calcium (2018 only), and iron (2018 only). The organizations reporting inadequate laboratory values in one or more nutrients for mandatory declaration (energy, protein, fat, carbohydrate, or salt equivalent) were 11 and 15% of all organizations and 9 and 13% of public organizations in the 2017 and 2018 schemes, respectively. The approximate relative standard deviations for proficiency assessment (RSDr) were as follows: protein, 2%; fat, 3%; ash, 2%; moisture, 0.5%; carbohydrate, 9%; energy, 1%; sodium (salt equivalent), 4%; calcium, 7%; and iron, 7%. Notably, the large RSDr value for carbohydrate may cause inconsistency among laboratories in compliance tests for foods containing several grams or less of carbohydrate per 100 grams.

Development of Enzyme-Linked Immunosorbent Assay for Analysis of Total Aflatoxins Based on Monoclonal Antibody Reactive with Aflatoxins B1, B2, G1 and G2.

A direct competitive enzyme-linked immunosorbent assay (dc-ELISA) was developed for the determination of total amount of aflatoxin B1, B2, G1 and G2 (AFB1, AFB2, AFG1 and AFG2), using a mouse monoclonal antibody that shows similar reactivity to each of these AFs. The working range of the developed dc-ELISA was 50-230 pg/mL for AFB1, 50-270 pg/mL for AFB2, 60-390 pg/mL for AFG1 and 65-700 pg/mL for AFG2. The recovery of AFs from spiked roasted peanuts was 98％. Further, when 4 samples actually contaminated with AFB1, AFB2, AFG1 and AFG2 were examined, the results of dc-ELISA were highly correlated with the values assigned by the Food Analysis Performance Assessment Scheme. The developed dc-ELISA appears to be suitable for the determination of total AFs at concentrations around the maximum permitted level (10 µg/kg for all foods) in Japan.

[Enhancement of Pesticide Peak Response in GC-MS in the Presence of Multiple Co-Existing Reference Pesticides].

We carried out a collaborative study in six laboratories to confirm the universality of the enhancing effect of co-existing reference pesticides on the GC-MS peak response to a target pesticide (malathion, procymidone, or flucythrinate). First, we confirmed the response enhancement of the target pesticides with increasing numbers of co-existing reference pesticides in solution. Then, using diluted green soybean matrix, we analyzed the target pesticides with two types of matrix-matched calibration, containing the target pesticides or 166 other pesticides. In both cases, the response-enhancing effect of co-existing pesticides was confirmed in all laboratories. The enhancement was reduced by addition of green soybean matrix to the sample and calibration solutions. Our results show that it is necessary to estimate the peak response-enhancing effect of co-existing pesticides in the calibration solution to obtain accurate results with GC-MS determination. The enhancing effect could be reduced by addition of food matrix to the sample and calibration solutions.

Comparison of Assigned Values from Participants' Results, Spiked Concentrations of Test Samples, and Isotope Dilution Mass Spectrometric Results in Proficiency Testing for Pesticide Residue Analysis.

The Hatano Research Institute (HRI) at the Food and Drug Safety Center has recently organized a series of proficiency-testing (PT) programs called the "External Quality Control for Food Hygiene" in order to evaluate the analytical capability of testing laboratories that inspect food samples in accordance with the Food Sanitation Act. In one of these programs, Pesticide I, consensus values calculated from the participants' analytical results were used as assigned values, and the spiked concentrations of the prepared test samples were used for evaluating variation among individual participants. In the present study, the values obtained in the 2013-2015 rounds have been assessed by comparing the analytical results of the target pesticides obtained by using two different isotope-dilution MS (IDMS) methods. These two IDMS methods are based on a combination of different pretreatment protocols and different GC separation columns. The weighted means of the observed analytical results were higher than the corresponding assigned values, but showed good agreement with the spiked concentrations. These results indicate that the spiking concentrations of the test sample from HRI are reliable, and therefore, these values can be used to evaluate the trueness of the participants' analytical method.

Evaluation of the matrix-like effect in multiresidue pesticide analysis by gas chromatography with tandem mass spectrometry.

In multiresidue pesticide analysis using gas chromatography, it has long been recognized that an increase in the number of pesticides present in a standard solution can result in an enhancement of the peak responses of certain pesticides. Despite being widely acknowledged, this phenomenon has been rarely studied and is poorly understood. In this study, the authors have tentatively called this phenomenon the "matrix-like effect" and demonstrated it clearly using gas chromatography with tandem mass spectrometry. Five selected pesticides, namely, omethoate, terbufos, malathion, procymidone, and permethrin, and four internal standard candidates, namely, triphenyl phosphate, naphthalene-d8 , phenanthrene-d10 , and fluoranthene-d10 , were used to evaluate the matrix-like effect following the addition of 58, 108, and 166 other pesticides. With the exception of naphthalene-d8 , the responses of all evaluated pesticides and internal standard candidates were dramatically enhanced by the addition of up to 166 coexisting pesticides. The relative response factors of the five pesticides to each internal standard candidate were not constant under the conditions studied, meaning that these internal standard candidates did not adequately compensate for the matrix-like effect, at least for the five evaluated pesticides. The results revealed that the presence of various mixtures of pesticides in standard solutions might act as an unintentional analyte protectant, that is, some sort of troublesome "quasi-matrix."

In vitro and in vivo metabolism of N-adamantyl substituted urea-based soluble epoxide hydrolase inhibitors.

N,N'-disubstituted urea-based soluble epoxide hydrolase (sEH) inhibitors are promising therapeutics for hypertension, inflammation, and pain in multiple animal models. The drug absorption and pharmacological efficacy of these inhibitors have been reported extensively. However, the drug metabolism of these inhibitors is not well described. Here we reported the metabolic profile and associated biochemical studies of an N-adamantyl urea-based sEH inhibitor 1-adamantan-1-yl-3-(5-(2-(2-ethoxyethoxy)ethoxy)pentyl)urea (AEPU) in vitro and in vivo. The metabolites of AEPU were identified by interpretation of liquid chromatography-mass spectrometry (LC-MS), liquid chromatography-tandem mass spectrometry (LC-MS/MS) and/or NMR. In vitro, AEPU had three major positions for phase I metabolism including oxidations on the adamantyl moiety, urea nitrogen atoms, and cleavage of the polyethylene glycol chain. In a rodent model, the metabolites from the hydroxylation on the adamantyl group and nitrogen atom were existed in blood while the metabolites from cleavage of polyethylene glycol chain were not found in urine. The major metabolite found in rodent urine was 3-(3-adamantyl-ureido)-propanoic acid, a presumably from cleavage and oxidation of the polyethylene glycol moiety. All the metabolites found were active but less potent than AEPU at inhibiting human sEH. Furthermore, cytochrome P450 (CYP) 3A4 was found to be a major enzyme mediating AEPU metabolism. In conclusion, the metabolism of AEPU resulted from oxidation by CYP could be shared with other N-adamantyl-urea-based compounds. These findings suggest possible therapeutic roles for AEPU and new strategies for drug design in this series of possible drugs.

The complete control of murine pregnancy from embryo implantation to parturition.

The ovary is the main secretory source of progestin and estrogen and is indispensable to the maintenance of all events of pregnancy in mice. The purpose of this study was to control all processes of pregnancy in mice, from embryo implantation to parturition, without ovaries. The ovaries were removed before embryo implantation, and a single injection of medroxyprogesterone acetate (MPA) was given. Embryo implantation was induced by leukemia inhibitory factor, which can substitute 17ß-estradiol (E(2)). Continuous exposure to E(2) was necessary at mid-pregnancy, when placentation was completed. All mice sustained pregnancy without ovaries before parturition, which was initiated by the removal of E(2) and MPA. Murine pregnancy is a complicated process involving embryo implantation, placentation, and parturition. Complete control of pregnancy was achieved with the simple treatment of MPA and E(2) after induction of embryo implantation. Here, time-dependent events in the uterus during pregnancy could be realized without the ovaries, because the initiation of each event could be stringently controlled by hormonal treatments.

Nasal instillation of nanoparticle-rich diesel exhaust particles slightly affects emotional behavior and learning capability in rats.

In the present study, in order to reveal novel adverse effects of ultrafine particles (UFP) on the central nervous system, the effects of nanoparticle-rich diesel exhaust particles (NRDEP; count mode diameter, 21.45 nm) on emotional behavior, learning capability and brain neurotransmitter levels were studied in rats by intranasal instillation (iNI). NRDEP (10 and 50 µg/rat) was instilled into 2-week old infant, male rats once a week for 4 weeks. Spontaneous motor activity measured was observed to be inverse to the dose level. In active avoidance tests using a shuttle box, NRDEP-treated animals showed a lower avoidance performance than control animals given air-instillation. The levels of dopamine and its metabolite (DOPAC) in the medial mammillary nucleus of the brain tended to be lower in the NRDEP-treated animals. From these results, although the effects of NRDEP by iNI on the emotionality and the brain neurotransmitter levels were not fully clear, the results obtained by avoidance testing suggested involvement of UFP in learning capability.

Attenuation of cisplatin nephrotoxicity by inhibition of soluble epoxide hydrolase.

Cisplatin is a highly effective chemotherapeutic agent against many tumors; however, it is also a potent nephrotoxicant. Given that there have been no significant advances in our ability to clinically manage acute renal failure since the advent of dialysis, the development of novel strategies to ablate nephrotoxicity would represent a significant development. In this study, we investigated the ability of an inhibitor of soluble epoxide hydrolase (sEH), n-butyl ester of 12-(3-adamantan-1-yl-ureiido)-dodecanoic acid (nbAUDA), to attenuate cisplatin-induced nephrotoxicity. nbAUDA is quickly converted to AUDA and results in maintenance of high AUDA levels in vivo. Subcutaneous administration of 40 mg/kg of nbAUDA to C3H mice every 24 h resulted in elevated blood levels of AUDA; this protocol was also associated with attenuation of nephrotoxicity induced by cisplatin (intraperitoneal injection) as assessed by BUN levels and histological evaluation of kidneys. This is the first report of the use of sEH inhibitors to protect against acute nephrotoxicity and suggests a therapeutic potential of these compounds.

Creatinine measurements in 24 h urine by liquid chromatography--tandem Mass Spectrometry.

A simple, sensitive, and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determining urinary creatinine was developed and used to evaluate 24 h urine samples collected during an exposure study. Urine (1 microL) was diluted with methanol and then directly applied to LC-MS/MS. Under electrospray ionization (ESI) conditions, the transition molecules of creatinine and creatinine- d3 were observed at m/ z 114 > 44 and m/ z 117 > 47, respectively. The retention time of creatinine was 0.59 min. The linear range was 1-2000 ng/mL, with a detection limit in urine of 1 ng/mL. LC-MS/MS and colorimetric end-point methods were significantly associated ( R2 = 0.8785, p < 0.0001). The LC-MS/MS method to determine creatinine in 24 h urine samples had shorter retention times, was more sensitive, reliable, reproducible, simple, selective, and used a smaller sample size than other LC-MS/MS or commercial methods.

Design of bioavailable derivatives of 12-(3-adamantan-1-yl-ureido)dodecanoic acid, a potent inhibitor of the soluble epoxide hydrolase.

The soluble epoxide hydrolase (sEH) plays an important role in the metabolism of endogenous chemical mediators involved in blood pressure regulation and vascular inflammation. 12-(3-Adamantan-1-yl-ureido)-dodecanoic acid (AUDA, 1) is a very active inhibitor of sEH both in vitro and in vivo. However, its relatively high melting point and limited solubility in either water or oil-based solvents leads to difficulties in formulating the compound and often results in poor in vivo availability. We investigated the effect of derivatization of the acid functional group of inhibitor 1 on the inhibition potencies, physical properties, and pharmacokinetic properties. For human sEH, similar inhibition potency was obtained when the acid of compound 1 was modified to esters (2-15). The resulting compounds exhibited improved physical properties (23-66 degrees C lower melting point and 5-fold better solubility in oil). Pharmacokinetic studies showed that the esters possess improved oral bioavailability in mice. On the other hand, amide derivatives of AUDA 1 did not show significant improvement in inhibition potencies or physical properties (higher melting points and lower solubility). The esterification of 1 results in compounds that are easier to formulate in animal food and in triglycerides for gavage and other routes of administration, making it easier to study the biological effects of sEH inhibition in vivo.

High-throughput pharmacokinetic method: cassette dosing in mice associated with minuscule serial bleedings and LC/MS/MS analysis.

A method for pharmacokinetic studies using cassette dosing associated with serial bleeding in mice is described. PK profiles of four soluble epoxide hydrolase inhibitors were determined following oral, subcutaneous or intraperitoneal administration individually or in cassette dosing. Parent analyses were performed on only 5 microL of whole blood from serial bleeds (up to 10 per animal), by LC/MS/MS. An accuracy (88-100%) and precision (<10% RSD) were observed, leading to reliable datum points for PK calculation. PK profiles, T(max), C(max) and half-life values after cassette dosing were similar to the individual PK results. This method dramatically increases speed of data collection while dramatically reducing cost and animal usage. The results presented here clearly indicate that this proposed method could be applicable to high-throughput PK studies.

An orally active epoxide hydrolase inhibitor lowers blood pressure and provides renal protection in salt-sensitive hypertension.

The present study tested the hypothesis that increasing epoxyeicosatrienoic acids by inhibition of soluble epoxide hydrolase (sEH) would lower blood pressure and ameliorate renal damage in salt-sensitive hypertension. Rats were infused with angiotensin and fed a normal-salt diet or an 8% NaCl diet for 14 days. The sEH inhibitor, 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA), was given orally to angiotensin-infused animals during the 14-day period. Plasma AUDA metabolite levels were measured, and they averaged 10+/-2 ng/mL in normal-salt angiotensin hypertension and 19+/-3 ng/mL in high-salt angiotensin hypertension on day 14 in the animals administered the sEH inhibitor. Mean arterial blood pressure averaged 161+/-4 mm Hg in normal-salt and 172+/-5 mm Hg in the high-salt angiotensin hypertension groups on day 14. EH inhibitor treatment significantly lowered blood pressure to 140+/-5 mm Hg in the normal-salt angiotensin hypertension group and to 151+/-6 mm Hg in the high-salt angiotensin hypertension group on day 14. The lower arterial blood pressures in the AUDA-treated groups were associated with increased urinary epoxide-to-diol ratios. Urinary microalbumin levels were measured, and ED-1 staining was used to determine renal damage and macrophage infiltration in the groups. Two weeks of AUDA treatment decreased urinary microalbumin excretion in the normal-salt and high-salt angiotensin hypertension groups and macrophage number in the high-salt angiotensin hypertension group. These data demonstrate that sEH inhibition lowers blood pressure and ameliorates renal damage in angiotensin-dependent, salt-sensitive hypertension.

Evaluation of alpha-cyano ethers as fluorescent substrates for assay of cytochrome P450 enzyme activity.

We have previously reported the synthesis of four alpha-cyano-containing ethers based on 2-naphthaldehyde (2-NA) as cytochrome P450 (P450) fluorescent substrates. Activity detection was based on the formation of fluorescent 2-NA following substrate hydrolysis. A major limitation of these substrates was the need to remove NADPH, a required cofactor for P450 oxidation, before measuring 2-NA fluorescence. In this article, we report the synthesis of a new series of novel P450 substrates using 6-dimethylamino-2-naphthaldehyde (6-DMANA), which has a green fluorescent emission that is well separated from the NADPH spectrum. A major advantage of the 6-DMANA substrates is that NADPH removal is not required before fluorescence detection. We used eight alpha-cyano ether-based substrates to determine the O-dealkylation activity of human, mouse, and rat liver microsomes. In addition, substrate activities were compared with the commercial substrate 7-ethoxyresorufin (7-ER). The catalytic turnover rates of both the 6-DMANA- and 2-NA-based substrates were in some cases threefold faster than the catalytic turnover rate of 7-ER. The 2-NA-based substrates had greater turnover than did the 6-DMANA-based substrates. Murine and rat liver microsomes prepared from animals that had been treated with various P450 inducers were used to examine for isozyme-selective turnover of the substrates. The vastly improved optical properties and synthetic flexibility of the alpha-cyano ether compounds suggest that they are possibly good general P450 substrates.

Activation of peroxisome proliferator-activated receptor alpha by substituted urea-derived soluble epoxide hydrolase inhibitors.

Soluble epoxide hydrolase (sEH) plays a major role in regulating vascular epoxyeicosatrienoic acid metabolism and function, and substituted urea derivatives that inhibit sEH activity reduce blood pressure in hypertensive rats. We found that substituted urea derivatives containing a dodecanoic acid group, besides effectively inhibiting sEH, increased peroxisome proliferator-activated receptor (PPAR) alpha activity. In PPARalpha transfected COS-7 cells, treatment with 10 microM N-cyclohexyl-N'-dodecanoic acid urea (CUDA) or N-adamantanyl-N'-dodecanoic acid urea (AUDA) produced 6- and 3-fold increases, respectively, in PPARalpha activation. Neither CUDA nor AUDA activated PPARdelta or PPARgamma directly, indicating selectivity for PPARalpha. CUDA did not alter PPARalpha protein expression, and it competitively inhibited the binding of Wy-14643 (pirinixic acid) to the ligand binding domain of PPARalpha, suggesting that it functions as a PPARalpha ligand. CUDA and AUDA were metabolized to chain-shortened beta-oxidation products, a process that reduced their potency as sEH inhibitors and their ability to bind and activate PPARalpha. N,N'-Dicylclohexylurea and N-cyclohexyl-N'-dodecylurea, sEH inhibitors that do not contain a carboxylic acid group, did not activate PPARalpha. In HepG2 cells, CUDA increased the expression of the PPARalpha-responsive gene carnitine palmitoyltransferase 1A. We conclude that CUDA and AUDA, by virtue of their carboxylic acid substitution, activate PPARalpha in addition to potently inhibiting sEH. Further development of these compounds could lead to a class of agents with hypotensive and lipid-lowering properties that may be valuable for the prevention and treatment of cardiovascular disease.

Attenuation of tobacco smoke-induced lung inflammation by treatment with a soluble epoxide hydrolase inhibitor.

Changes in the lungs due to smoking include inflammation, epithelial damage, and remodeling of the airways. Airway inflammation is likely to play a critical role in the genesis and progression of tobacco smoke-induced airway disease. Soluble epoxide hydrolase (sEH) is involved in the metabolism of endogenous chemical mediators that play an important role in inflammation. Epoxyeicosatrienoic acids (EETs) have demonstrated antiinflammatory properties, and hydrolysis of these epoxides by sEH is known to diminish this activity. To examine whether acute tobacco smoke-induced inflammation could be reduced by a sEH inhibitor, 12-(3-adamantane-1-yl-ureido)-dodecanoic acid n-butyl ester was given by daily s.c. injection to spontaneously hypertensive rats exposed to filtered air or tobacco smoke for a period of 3 days (6 h/day). Acute exposure to tobacco smoke significantly increased by 3.2-fold (P <0.05) the number of cells recovered by bronchoalveolar lavage. The sEH inhibitor significantly decreased total bronchoalveolar lavage cell number by 37% in tobacco smoke-exposed rats with significant reductions noted in neutrophils, alveolar macrophages, and lymphocytes. A combination of sEH inhibitor and EETs was more significant in its ability to further reduce tobacco smoke-induced inflammation compared with the sEH inhibitor alone. The sEH inhibitor led to a shift in some plasma epoxides and diols that are consistent with the hypothetical action of these compounds. We conclude that an sEH inhibitor, in the presence or absence of EETs, can attenuate, in part, inflammation associated with acute exposure to tobacco smoke.

Determination of pyrethroid residues in agricultural products by an enzyme-linked immunosorbent assay.

To determine cypermethrin and permethrin in agricultural products, a competitive enzyme-linked immunosorbent assay (ELISA) method was employed. The matrix interferences were minimized by direct dilution of the extracts. No further cleanup was needed. A minimum matrix effect with a 1:10 dilution of white wine for cypermethrin and a 1:200 dilution of red and white wines, fruits, and vegetables for permethrin was found when phosphate-buffered saline containing 40% methanol was employed as the diluent. Good recoveries of spiked levels were observed. The mean percentage recoveries of cypermethrin spiked in white wine and permethrin spiked in red and white wines were 99.7, 74, and 78%, respectively. The mean percentage recoveries of permethrin spiked in apple, banana, cucumber, lettuce, onion, and peach were 99.2, 105, 70.2, 97.5, 94.4, and 89.4%, respectively. Validation of the ELISA method with permethrin-spiked lettuce and peach was carried out using gas chromatography with mass spectrometry, resulting in a good recovery and correlation.

Hapten and antibody production for a sensitive immunoassay determining a human urinary metabolite of the pyrethroid insecticide permethrin.

Permethrin is the most popular synthetic pyrethroid insecticide in agriculture and public health. For the development of the enzyme-linked immunosorbent assay (ELISA) to evaluate human exposure to permethrin, the glycine conjugate (DCCA-glycine) of a major metabolite, cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (DCCA), of permethrin was established as the target analyte. Four different types of the cis- and trans-isomers of immunizing haptens were synthesized as follows: N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)glycine (hapten 3), N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)-4-amino-l-phenylalanine (hapten 5), N-(N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)glycine)amino-6-(2,4-dinitrophenyl)aminohexanoic acid (hapten 9), and N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)glycine-4-oxobutanoic acid (hapten 24). Sixteen polyclonal antibodies produced against each cis- or trans-hapten-thyroglobulin conjugate as immunogens were screened against numerous hapten-bovine serum albumin conjugates as coating antigens. Six ELISAs with both a heterologous hapten structure and a heterologous hapten configuration (cis/trans or trans/cis) between antibody and coating antigen showed a high sensitivity for the target analyte. The IC50 was 1.3, 2.1, and 2.2 microg/L for the trans-target analyte and 0.4, 2.3, and 2.8 microg/L for the cis-target analyte. The immunizing haptens, except for hapten 5, provided the target specific antibodies. Molecular modeling of the haptens supported the selection of reasonable immunizing haptens that best mimicked the target analyte. Hapten 5 was suitable as a coating antigen rather than as an immunogen since it had a different geometry. Very low cross-reactivities were measured to permethrin, its free metabolite (DCCA), PBA-glycine conjugate, and glycine. The ELISA will be optimized for the detection of total cis/trans-DCCA-glycine in human urine samples.

Soluble epoxide hydrolase inhibition protects the kidney from hypertension-induced damage.

Epoxyeicosatrienoic acids (EET) have antihypertensive and anti-inflammatory properties and play a role in the maintenance of renal vascular function. A novel approach to increase EET levels is to inhibit epoxide hydrolase enzymes that are responsible for conversion of biologically active EET to dihydroxyeicosatrienoic acids (DHET). We hypothesized that soluble epoxide hydrolase (SEH) inhibition would improve renal vascular function and ameliorate hypertension induced renal damage. Chronic administration of the specific SEH inhibitor 1-cyclohexyl-3-dodecylurea (CDU, 3 mg/d) for 10 d lowered BP in angiotensin hypertensive rats. The contribution of renal vascular SEH to afferent arteriolar function in angiotensin hypertension was also assessed. SEH protein expression was increased in renal microvessels from hypertensive rats. Although CDU did not change afferent arteriolar responsiveness to angiotensin in normotensive animals, CDU treatment significantly attenuated afferent arteriolar diameter responses to angiotensin in hypertensive kidneys from 51% +/- 8% to 28% +/- 7%. Protection of the renal vasculature and glomerulus during chronic CDU administration was demonstrated by histology. Urinary albumin excretion, an index of renal damage, was also lower in CDU-treated hypertensive rats. These data demonstrate that SEH inhibition has antihypertensive and renal vascular protective effects in angiotensin hypertension and suggests that SEH inhibitors may be a useful therapeutic intervention for cardiovascular diseases.

Design, synthesis, and biological activity of 1,3-disubstituted ureas as potent inhibitors of the soluble epoxide hydrolase of increased water solubility.

The soluble epoxide hydrolase (sEH) is involved in the metabolism of endogenous chemical mediators that play an important role in blood pressure regulation and inflammation. 1,3-Disubstituted ureas are potent inhibitors of sEH that are active both in vitro and in vivo. However, their poor solubility in either water or lipid reduces their in vivo efficacy and makes them difficult to formulate. To improve these physical properties, the effect of incorporating polar functional groups into one of the alkyl chains was evaluated on their inhibitor potencies, water solubility, octanol/water partition coefficients (log P), and melting points. No loss of inhibition potency was observed when a polar functional group was incorporated at least five atoms ( approximately 7.5 A) from the central urea carbonyl. In addition, the presence of a polar group at least 11 atoms away from the urea carbonyl group for the mouse and human sEHs, respectively, did not alter the inhibitor potency. The resulting compounds have better water solubility and generally lower log P values and melting points than nonfunctionalized liphophilic ureas. These properties will make the compounds more bioavailable and more soluble in either water- or oil-based formulations.