Soluble Epoxide Hydrolase Inhibition Attenuates Proteinuria by Alleviating Renal Inflammation and Podocyte Injuries in Adriamycin-Induced Nephropathy.

Soluble epoxide hydrolase (sEH) has previously been demonstrated to play an important part in kidney diseases by hydrolyzing renoprotective epoxyeicosatrienoic acids to their less active diols. However, little is known about the role of sEH in primary glomerular diseases. Here, we investigated the effects of sEH inhibition on proteinuria in primary glomerular diseases and the underlying mechanism. The expression of sEH in the renal tubules of patients with minimal change disease, IgA nephropathy, and membranous nephropathy was significantly increased. Renal sEH expression level was positively correlated with the 24 h urine protein excretion and negatively correlated with serum albumin. In the animal model of Adriamycin (ADR)-induced nephropathy, renal sEH mRNA and protein expression increased significantly. Pharmacological inhibition of sEH with AUDA effectively reduced urine protein excretion and attenuated renal pathological damage. Furthermore, sEH inhibition markedly abrogated the abnormal expressions of nephrin and desmin in glomerular podocytes induced by ADR. More importantly, AUDA treatment inhibited renal NF-κB activation and reduced TNF-α levels in rats with ADR-induced nephropathy. Overall, our findings suggest that sEH inhibition ameliorates renal inflammation and podocyte injury, thus reducing proteinuria and exerting renoprotective effects. Targeting sEH might be a potential strategy for the treatment of proteinuria in primary glomerular diseases.

Improving Hydrolytic Activity and Enantioselectivity of Epoxide Hydrolase from Phanerochaete chrysosporium by Directed Evolution.

Epoxide hydrolases (EHs) catalyze the conversion of epoxides into vicinal diols. The epoxide hydrolase gene from P. chrysosporium was previously cloned and subjected to site-directed mutation to study its enzyme activity, but the results were unsatisfactory. This study used error prone PCR and DNA shuffling to construct a PchEHA mutation library. We performed mutation-site combinations on PchEHA based on enzyme activity measurement results combined with directed evolution technology. More than 15,000 mutants were randomly selected for the preliminary screening of PchEHA enzyme activity alongside 38 mutant strains with increased enzyme activity or enantioselectivity. Protein expression and purification were conducted to determine the hydrolytic activity of PchEHA, and three mutants increased their activity by more than 95% compared with that of the wt. After multiple rounds of screening and site-specific mutagenesis, we found that F3 offers the best enzyme activity and enantioselectivity; furthermore, the molecular docking results confirmed this result. Overall, this study uncovered novel mutants with potential value as industrial biocatalysts.

Discovery of Orally Active Phenylquinoline-Based Soluble Epoxide Hydrolase Inhibitors with Anti-Inflammatory and Analgesic Activity.

Currently, there are no specific drugs for treating acute pancreatitis. Soluble epoxide hydrolase (sEH) inhibitors show promise, but face challenges like low blood drug concentrations and potential adverse effects on CYP enzymes and the human ether-a-go-go-related gene (hERG). In this study, an approach involving scaffold hopping and structure-activity guided optimization was employed to design a series of phenylquinoline-based sEH inhibitors. Among these compounds, DJ-53 exhibited potent in vitro and in vivo effects in alleviating pain and reducing inflammation. The in vivo mechanism of action involved inhibiting sEH enzyme activity, thereby increasing levels of anti-inflammatory epoxyeicosatrienoic acids (EETs) and decreasing levels of proinflammatory dihydroxyeicosatrienoic acids (DHETs). Importantly, DJ-53 showed exceptional oral bioavailability and pharmacokinetics, while avoiding inhibition of CYP enzymes or the hERG channel. These results highlight DJ-53's potential as a new lead compound for anti-inflammatory and analgesic applications and provide a safe and effective scaffold for developing sEH inhibitors.

Restoration of ARA metabolic disorders in vascular smooth muscle cells alleviates intimal hyperplasia.

Intimal hyperplasia (IH) is an innegligible issue for patients undergoing interventional therapy. The proliferation and migration of vascular smooth muscle cells (VSMCs) induced by platelet-derived growth factor-BB (PDGF-BB) are critical events in the development of IH. While the exact mechanism and effective target for IH needs further investigation. Metabolic disorders of arachidonic acid (ARA) are involved in the occurrence and progression of various diseases. In this study, we found that the expressions of soluble epoxide hydrolase (sEH) and cyclooxygenase-2 (COX-2) were significantly increased in the VSMCs during balloon injury-induced IH. Then, we employed a COX-2/sEH dual inhibitor PTUPB to increase the concentration of epoxyeicosatrienoic acids (EETs) while prevent the release of pro-inflammatory prostaglandins. Results showed that PTUPB treatment significantly reduced neointimal thickening induced by balloon injury in rats in vivo and inhibited PDGF-BB-induced proliferation and migration of VSMCs in vitro. Our results showed that PTUPB may reverse the phenotypic transition of VSMCs by inhibiting Pttg1 expression. In conclusion, we found that the dysfunction of ARA metabolism in VSMCs contributes to IH, and the COX-2/sEH dual inhibitor PTUPB attenuates IH progression by reversing the phenotypic switch in VSMC through the Sirt1/Pttg1 pathway.

Engineering an Epoxide Hydrolase for Chemoenzymatic Asymmetric Synthesis of Chiral Triazole Fungicide (S)- and (R)-Flutriafol.

Flutriafol, a globally utilized triazole fungicide in agriculture, is typically applied as a racemic mixture, but its enantiomers differ in bioactivity and environmental impact. The synthesis of flutriafol enantiomers is critically dependent on chiral precursors: 2,2-bisaryl-substituted oxirane [(2-fluorophenyl)-2-(4-fluorophenyl)oxirane, 1a] and 1,2-diol [1-(2-fluorophenyl)-1-(4-fluorophenyl)ethane-1,2-diol, 1b]. Here, we engineered a Rhodotorula paludigensis epoxide hydrolase (RpEH), obtaining mutant Escherichia coli/RpehH336W/L360F with a 6.4-fold enhanced enantiomeric ratio (E) from 5.5 to 35.4. This enabled a gram-scale resolution of rac-1a by E. coli/RpehH336W/L360F, producing (S)-1a (98.2% ees) and (R)-1b (75.0% eep) with 44.3 and 55.7% analytical yields, respectively. As follows, chiral (S)-flutriafol (98.2% ee) and (R)-flutriafol (75.0% ee) were easily synthesized by a one-step chemocatalytic process from (S)-1a and a two-step chemocatalytic process from (R)-1b, respectively. This chemoenzymatic approach offers a superior alternative for the asymmetric synthesis of flutriafol enantiomers. Furthermore, molecular dynamics simulations revealed insight into the enantioselectivity improvement of RpEH toward bulky 2,2-bisaryl-substituted oxirane 1a.

Gasdermin D-mediated metabolic crosstalk promotes tissue repair.

The establishment of an early pro-regenerative niche is crucial for tissue regeneration1,2. Gasdermin D (GSDMD)-dependent pyroptosis accounts for the release of inflammatory cytokines upon various insults3-5. However, little is known about its role in tissue regeneration followed by homeostatic maintenance. Here we show that macrophage GSDMD deficiency delays tissue recovery but has little effect on the local inflammatory milieu or the lytic pyroptosis process. Profiling of the metabolite secretome of hyperactivated macrophages revealed a non-canonical metabolite-secreting function of GSDMD. We further identified 11,12-epoxyeicosatrienoic acid (11,12-EET) as a bioactive, pro-healing oxylipin that is secreted from hyperactive macrophages in a GSDMD-dependent manner. Accumulation of 11,12-EET by direct supplementation or deletion of Ephx2, which encodes a 11,12-EET-hydrolytic enzyme, accelerated muscle regeneration. We further demonstrated that EPHX2 accumulated within aged muscle, and that consecutive 11,12-EET treatment rejuvenated aged muscle. Mechanistically, 11,12-EET amplifies fibroblast growth factor signalling by modulating liquid-liquid phase separation of fibroblast growth factors, thereby boosting the activation and proliferation of muscle stem cells. These data depict a GSDMD-guided metabolite crosstalk between macrophages and muscle stem cells that governs the repair process, which offers insights with therapeutic implications for the regeneration of injured or aged tissues.

Corn Peptides Alleviate Nonalcoholic Fatty Liver Fibrosis in Mice by Inhibiting NLRP3 Inflammasome Activation and Regulating Gut Microbiota.

This study aimed to investigate the effects of corn gluten-derived soluble epoxide hydrolase (sEH) inhibitory peptides on nonalcoholic fatty liver fibrosis induced by a high-fat diet and carbon tetrachloride in mice. Mice treated with corn peptides at doses of 500 or 1000 mg/kg/d for 4 weeks exhibited reduced sEH activity in serum and liver, enhanced lipid metabolism, and decreased lipid accumulation and oxidative stress. Corn peptides effectively downregulated the mRNA levels of Pro-IL-1ß, Pro-IL-18, NOD-like receptor protein 3 (NLRP3), ASC, Pro-caspase-1, Caspase-1, and GSDMD in the liver. This hepatoprotective effect of corn peptides by inhibiting NLRP3 inflammasome activation was further validated in H2O2-induced HepG2 cells. Moreover, corn peptides restored the composition of the gut microbiota and promoted short-chain fatty acid production. This study provides evidence that corn-derived sEH inhibitory peptides have hepatoprotective activity against nonalcoholic fatty liver fibrosis by suppressing NLRP3 inflammasome activation and modulating gut microbiota.

The role of soluble epoxide hydrolase in the intestine.

The soluble epoxide hydrolase (sEH; encoded by the EPHX2 gene) is an α/ß hydrolase fold protein that is, widely distributed throughout the body. Recent studies have highlighted that sEH, in the metabolism of polyunsaturated fatty acids, plays a part in the pathogenesis of various diseases, including cardiovascular disease, Alzheimer's disease and intestine-associated disease. This review discusses the current findings on the role of sEH in the development of intestine- and intestine-associated diseases, including colitis, colorectal cancer, and other intestinal diseases, as well as the potential underlying mechanisms involved.

Upregulated Nuclear Expression of Soluble Epoxide Hydrolase Predicts Poor Outcome in Breast Cancer Patients: Importance of the Digital Pathology Approach.

Breast cancer (BC) is the most common cancer in women, with incidence rates increasing globally in recent years. Therefore, it is important to find new molecules with prognostic and therapeutic value to improve therapeutic response and quality of life. The polyunsaturated fatty acids (PUFAs) metabolic pathway participates in various physiological processes, as well as in the development of malignancies. Although aberrancies in the PUFAs metabolic pathway have been implicated in carcinogenesis, the functional and clinical relevance of this pathway has not been well explored in BC. To evaluate the clinical significance of soluble epoxide hydrolase (EPHX2) expression in Mexican patients with BC using tissue microarrays (TMAs) and digital pathology (DP). Immunohistochemical analyses were performed on 11 TMAs with 267 BC samples to quantify this enzyme. Using DP, EPHX2 protein expression was evaluated solely in tumor areas. The association of EPHX2 with overall survival (OS) was detected through bioinformatic analysis in public databases and confirmed in our cohort via Cox regression analysis. Clear nuclear expression of EPHX2 was identified. Receiver operating characteristics (ROC) curves revealed the optimal cutoff point at 2.847062 × 10-3 pixels, with sensitivity of 69.2% and specificity of 67%. Stratification based on this cutoff value showed elevated EPHX2 expression in multiple clinicopathological features, including older age and nuclear grade, human epidermal growth factor receptor 2 (HER2) and triple negative breast cancer (TNBC) subtypes, and recurrence. Kaplan-Meier curves demonstrated how higher nuclear expression of EPHX2 predicts shorter OS. Consistently, multivariate analysis confirmed EPHX2 as an independent predictor of OS, with a hazard ratio (HR) of 3.483 and a 95% confidence interval of 1.804-6.724 (p < 0.001). Our study demonstrates for the first time that nuclear overexpression of EPHX2 is a predictor of poor prognosis in BC patients. The DP approach was instrumental in identifying this significant association. Our study provides valuable insights into the potential clinical utility of EPHX2 as a prognostic biomarker and therapeutic target in BC.

Targeting the soluble epoxide hydrolase pathway as a novel therapeutic approach for the treatment of pain.

Chronic pain is a major burden and the complexities of chronic pain pathophysiology, including both peripheral and central sensitisation mechanisms, involves multiple cell types (neuronal, immune, neuroimmune, and vascular) which substantially complicates the development of new effective analgesic treatments. The epoxy fatty acids (EpFAs), including the epoxyeicosatrienoic acids (EETs), are derived from the metabolism of polyunsaturated fatty acids (PUFAs) via the cytochrome P450 enzymatic pathway and act to shut-down inflammatory signalling and provide analgesia. The EpFAs are rapidly metabolised by the enzyme soluble epoxide hydrolase (sEH) into their corresponding diol metabolites, which recent studies suggest are pro-inflammatory and pro-nociceptive. This review discusses clinical and mechanistic evidence for targeting the sEH pathway for the treatment of pain.

Preclinical Evaluation of Soluble Epoxide Hydrolase Inhibitor AMHDU against Neuropathic Pain.

Inhibition of soluble epoxide hydrolase (sEH) is a promising therapeutic strategy for treating neuropathic pain. These inhibitors effectively reduce diabetic neuropathic pain and inflammation induced by Freund's adjuvant which makes them a suitable alternative to traditional opioids. This study showcased the notable analgesic effects of compound AMHDU (1,1'-(hexane-1,6-diyl)bis(3-((adamantan-1-yl)methyl)urea)) in both inflammatory and diabetic neuropathy models. While lacking anti-inflammatory properties in a paw edema model, AMHDU is comparable to celecoxib as an analgesic in 30 mg/kg dose administrated by intraperitoneal injection. In a diabetic tactile allodynia model, AMHDU showed a prominent analgesic activity in 10 mg/kg intraperitoneal dose (p < 0.05). The effect is comparable to that of gabapentin, but without the risk of dependence due to a different mechanism of action. Low acute oral toxicity (>2000 mg/kg) and a high therapeutic index makes AMHDU a promising candidate for further structure optimization and preclinical evaluation.

Multifaceted exploration of acylthiourea compounds: In vitro cytotoxicity, DFT calculations, molecular docking and dynamics simulation studies.

This study reports the synthesis and analysis of biologically active acylthiourea compounds (1 and 2) with a cyclohexyl moiety. The compounds were characterized using UV-Visible, FT-IR, 1H/13C NMR, and elemental analysis. The crystal structure of 2 was solved, revealing intra- and inter-molecular hydrogen bonds. Density functional theory (DFT) calculations provided insights into chemical reactivity and non-covalent interactions. Cytotoxicity assays showed the cyclohexyl group enhanced the activity of compound 2 compared to compound 1. Epoxide hydrolase 1 was predicted as the enzyme target for both compounds. We modeled the structure of epoxide hydrolase 1 and performed molecular dynamics simulation and docking studies. Additionally, in silico docking with SARS-CoV-2 main protease, human ACE2, and avian influenza H5N1 hemagglutinin indicated strong binding potential of the compounds. This integrated approach improves our understanding of the biological potential of acylthiourea derivatives.

Triazine herbicide prometryn alters epoxide hydrolase activity and increases cytochrome P450 metabolites in murine livers via lipidomic profiling.

Oxylipins are a group of bioactive fatty acid metabolites generated via enzymatic oxygenation. They are notably involved in inflammation, pain, vascular tone, hemostasis, thrombosis, immunity, and coagulation. Oxylipins have become the focus of therapeutic intervention since they are implicated in many conditions, such as nonalcoholic fatty liver disease, cardiovascular disease, and aging. The liver plays a crucial role in lipid metabolism and distribution throughout the organism. Long-term exposure to pesticides is suspected to contribute to hepatic carcinogenesis via notable disruption of lipid metabolism. Prometryn is a methylthio-s-triazine herbicide used to control the growth of annual broadleaf and grass weeds in many cultivated plants. The amounts of prometryn documented in the environment, mainly waters, soil and plants used for human and domestic consumption are significantly high. Previous research revealed that prometryn decreased liver development during zebrafish embryogenesis. To understand the mechanisms by which prometryn could induce hepatotoxicity, the effect of prometryn (185 mg/kg every 48 h for seven days) was investigated on hepatic and plasma oxylipin levels in mice. Using an unbiased LC-MS/MS-based lipidomics approach, prometryn was found to alter oxylipins metabolites that are mainly derived from cytochrome P450 (CYP) and lipoxygenase (LOX) in both mice liver and plasma. Lipidomic analysis revealed that the hepatotoxic effects of prometryn are associated with increased epoxide hydrolase (EH) products, increased sEH and mEH enzymatic activities, and induction of oxidative stress. Furthermore, 9-HODE and 13-HODE levels were significantly increased in prometryn treated mice liver, suggesting increased levels of oxidation products. Together, these results support that sEH may be an important component of pesticide-induced liver toxicity.

Tomato Spotted Wilt Virus Suppresses the Antiviral Response of the Insect Vector, Frankliniella occidentalis, by Elevating an Immunosuppressive C18 Oxylipin Level Using Its Virulent Factor, NSs.

Orthotospovirus tomatomaculae (tomato spotted wilt virus, TSWV) is transmitted by the western flower thrips, Frankliniella occidentalis. Epoxyoctadecamonoenoic acids (EpOMEs) function as immune-suppressive factors, particularly in insects infected by viral pathogens. These oxylipins are produced by cytochrome P450 monooxygenases (CYPs) and are degraded by soluble epoxide hydrolase (sEH). In this study, we tested the hypothesis that TSWV modulates the EpOME level in the thrips to suppress antiviral responses and enhance its replication. TSWV infection significantly elevated both 9,10-EpOME and 12,13-EpOME levels. Following TSWV infection, the larvae displayed apoptosis in the midgut along with the upregulated expression of four caspase genes. However, the addition of EpOME to the viral treatment notably reduced apoptosis and downregulated caspase gene expressions, which led to a marked increase in TSWV titers. The CYP and sEH genes of F. occidentalis were identified, and their expression manipulation using RNA interference (RNAi) treatments led to significant alternations in the insect's immune responses and TSWV viral titers. To ascertain which viral factor influences the host EpOME levels, specialized RNAi treatments targeting genes encoded by TSWV were administered to larvae infected with TSWV. These treatments demonstrated that NSS expression is pivotal in manipulating the genes involved in EpOME metabolism. These results indicate that NSs of TSWV are crucially linked with the elevation of host insect EpOME levels and play a key role in suppressing the antiviral responses of F. occidentalis.

Inhibition of Soluble Epoxide Hydrolase by Cembranoid Diterpenes from Soft Coral Sinularia maxima: Enzyme Kinetics, Molecular Docking, and Molecular Dynamics.

Soluble epoxide hydrolase (sEH) is essential for converting epoxy fatty acids, such as epoxyeicosatrienoic acids (EETs), into their dihydroxy forms. EETs play a crucial role in regulating blood pressure, mediating anti-inflammatory responses, and modulating pain, making sEH a key target for therapeutic interventions. Current research is increasingly focused on identifying sEH inhibitors from natural sources, particularly marine environments, which are rich in bioactive compounds due to their unique metabolic adaptations. In this study, the sEH inhibitory activities of ten cembranoid diterpenes (1-10) isolated from the soft coral Sinularia maxima were evaluated. Among them, compounds 3 and 9 exhibited considerable sEH inhibition, with IC50 values of 70.68 µM and 78.83 µM, respectively. Enzyme kinetics analysis revealed that these two active compounds inhibit sEH through a non-competitive mode. Additionally, in silico approaches, including molecular docking and molecular dynamics simulations, confirmed their stability and interactions with sEH, highlighting their potential as natural therapeutic agents for managing cardiovascular and inflammatory diseases.

Airway extracellular LTA4H concentrations are governed by release from liver hepatocytes and changes in lung vascular permeability.

Leukotriene A4 hydrolase (LTA4H) is a bifunctional enzyme, with dual activities critical in defining the scale of tissue inflammation and pathology. LTA4H classically operates intracellularly, primarily within myeloid cells, to generate pro-inflammatory leukotriene B4. However, LTA4H also operates extracellularly to degrade the bioactive collagen fragment proline-glycine-proline to limit neutrophilic inflammation and pathological tissue remodeling. While the dichotomous functions of LTA4H are dictated by location, the cellular source of extracellular enzyme remains unknown. We demonstrate that airway extracellular LTA4H concentrations are governed by the level of pulmonary vascular permeability and influx of an abundant repository of blood-borne enzyme. In turn, blood LTA4H originates from liver hepatocytes, being released constitutively but further upregulated during an acute phase response. These findings have implications for our understanding of how inflammation and repair are regulated and how perturbations to the LTA4H axis may manifest in pathologies of chronic diseases.

Structure of epoxide hydrolase 2 from Mangifera indica throws light on the substrate specificity determinants of plant epoxide hydrolases.

Epoxide hydrolases (EHs) are a group of ubiquitous enzymes that catalyze hydrolysis of chemically reactive epoxides to yield corresponding dihydrodiols. Despite extensive studies on EHs from different clades, generic rules governing their substrate specificity determinants have remained elusive. Here, we present structural, biochemical and molecular dynamics simulation studies on MiEH2, a plant epoxide hydrolase from Mangifera indica. Comparative structure-function analysis of nine homologs of MiEH2, which include a few AlphaFold structural models, show that the two conserved tyrosines (MiEH2Y152 and MiEH2Y232) from the lid domain dissect substrate binding tunnel into two halves, forming substrate-binding-pocket one (BP1) and two (BP2). This compartmentalization offers diverse binding modes to their substrates, as exemplified by the binding of smaller aromatic substrates, such as styrene oxide (SO). Docking and molecular dynamics simulations reveal that the linear epoxy fatty acid substrates predominantly occupy BP1, while the aromatic substrates can bind to either BP1 or BP2. Furthermore, SO preferentially binds to BP2, by stacking against catalytically important histidine (MiEH2H297) with the conserved lid tyrosines engaging its epoxide oxygen. Residue (MiEH2L263) next to the catalytic aspartate (MiEH2D262) modulates substrate binding modes. Thus, the divergent binding modes correlate with the differential affinities of the EHs for their substrates. Furthermore, long-range dynamical coupling between the lid and core domains critically influences substrate enantioselectivity in plant EHs.

Design and Synthesis of sEH/HDAC6 Dual-Targeting Inhibitors for the Treatment of Inflammatory Pain.

Soluble epoxide hydrolase (sEH) and HDAC6 mediate the NF-κB pathway in inflammatory responses, and their inhibitors exhibit powerful anti-inflammatory and analgesic activities in treating both inflammation and pain. Therefore, a series of dual-targeting inhibitors containing urea or squaramide and hydroxamic acid moieties were designed and synthesized, and their role as a new sEH/HDAC6 dual-targeting inhibitor in inflammatory pain was evaluated in a formalin-induced mice model and a xylene-induced mouse ear swelling model. Among them, compounds 28g and 28j showed the best inhibitory and selectivity of sEH and HDAC6. Compound 28g had satisfactory pharmacokinetic characteristics in rats. Following administration at 30 mg/kg, compound 28g exhibited more effective analgesic activity than either an sEH inhibitor (GL-B437) or an HDAC6 inhibitor (Rocilinostat) alone and coadministration of both inhibitors. Thus, these novel sEH/HDAC6 dual-targeting inhibitors exhibited powerful analgesic activity in nociceptive behavior and are worthy of further development.

Evaluation of the Therapeutic Potential of Sulfonyl Urea Derivatives as Soluble Epoxide Hydrolase (sEH) Inhibitors.

The inhibition of soluble epoxide hydrolase (sEH) can reduce the level of dihydroxyeicosatrienoic acids (DHETs) effectively maintaining endogenous epoxyeicosatrienoic acids (EETs) levels, resulting in the amelioration of inflammation and pain. Consequently, the development of sEH inhibitors has been a prominent research area for over two decades. In the present study, we synthesized and evaluated sulfonyl urea derivatives for their potential to inhibit sEH. These compounds underwent extensive in vitro investigation, revealing their potency against human and mouse sEH, with 4f showing the most promising sEH inhibitory potential. When subjected to lipopolysaccharide (LPS)-induced acute lung injury (ALI) in studies in mice, compound 4f manifested promising anti-inflammatory efficacy. We investigated the analgesic efficacy of sEH inhibitor 4f in a murine pain model of tail-flick reflex. These results validate the role of sEH inhibition in inflammatory diseases and pave the way for the rational design and optimization of sEH inhibitors based on a sulfonyl urea template.

Cytochrome P450-soluble epoxide hydrolase oxylipins, depression and cognition in type 2 diabetes.

AIMS: This study examined serum cytochrome P450-soluble epoxide hydrolase (CYP450-sEH) oxylipins and depressive symptoms together in relation to cognitive performance in individuals with type 2 diabetes mellitus (T2DM). METHODS: Clinically cognitively normal T2DM individuals were recruited (NCT04455867). Depressive symptom severity was assessed using the Beck Depression Inventory-II (BDI-II; total scores ≤13 indicated minimal depressive symptoms and ≥ 14 indicated significant depressive symptoms). Executive function and verbal memory were assessed. Fasting serum oxylipins were quantified by ultra-high-performance liquid chromatography tandem mass-spectrometry. RESULTS: The study included 85 participants with minimal depressive symptoms and 27 with significant symptoms (mean age: 63.3 ± 9.8 years, 49 % women). In all participants, higher concentrations of linoleic acid derived sEH (12,13-dihydroxyoctadecamonoenoic acid; DiHOME) and CYP450 (12(13)-epoxyoctadecamonoenoic acid; EpOME) metabolites were associated with poorer executive function (F1,101 = 6.094, p = 0.015 and F1,101 = 5.598, p = 0.020, respectively). Concentrations of multiple sEH substrates interacted with depressive symptoms to predict 1) poorer executive function, including 9(10)-EpOME (F1,100 = 12.137, p < 0.001), 5(6)-epoxyeicosatrienoic acid (5(6)-EpETrE; F1,100 = 6.481, p = 0.012) and 11(12)-EpETrE (F1,100 = 4.409, p = 0.038), and 2) verbal memory, including 9(10)-EpOME (F1,100 = 4.286, p = 0.041), 5(6)-EpETrE (F1,100 = 6.845, p = 0.010), 11(12)-EpETrE (F1,100 = 3.981, p = 0.049) and 14(15)-EpETrE (F1,100 = 5.019, p = 0.027). CONCLUSIONS: Associations of CYP450-sEH metabolites and depressive symptoms with cognition highlight the biomarker and therapeutic potential of the CYP450-sEH pathway in T2DM.