Oxidation Of Polyunsaturated Fatty Acids Research Articles

Apolipoprotein E and Apolipoprotein E receptor 2 signaling as drug targets in Alzheimer’s disease

AbstractBackgroundAllelic variation in apolipoprotein E (APOE) is by far the greatest contributor to Alzheimer’s disease (AD) after age, but the mechanisms underlying how APOE impacts on the pathology of AD remain undefined. While most research is focusing on mechanisms associated with the presence of the APOE risk allele, several aspects of APOE biology remain poorly understood. In particular, the physiological relevance of APOE receptors and their impact on disease progression have been overlooked.MethodFerroptosis was induced in N27 neurons using multiple agents (erastin, RSL3) and toxicity was evaluated using different viability assays (MTT, Propidium iodide, LDH) and ferroptosis. N27 neurons were transfected with a plasmid encoding APOER2‐GFP fusion protein or a GFP‐expressing control vector, while recombinantly expressed and purified APOE was used as an APOE source.ResultHere, we present data supporting a function of APOE in tandem with APOER2 in protecting neurons from ferroptosis. Ferroptosis is a cell death pathway characterized by the accumulation of lethal lipid hydroperoxides resulting from iron‐dependent oxidation of polyunsaturated fatty acids. APOER2 expression in neurons resulted in increase in glutathione peroxidase 4 (GPX4) expression, which functions by converting toxic lipid peroxides into non‐toxic lipid alcohol and thus increases resistance to ferroptosis. We further report that APOER2 expression potentiates APOE‐mediated protection from ferroptotic cell death in in N27 neurons. Further mechanistic studies are ongoing to validate the underlying mechanism and the involved signaling cascades.ConclusionWe present evidence for the involvement of APOE and APOER2 in neuronal protection from ferroptotic cell death. These findings represent new drug targets that can be explored to slowdown neurodegeneration in AD.Funding: This study was supported by grants from the Alzheimer’s Association and National Health & Medical Research Council of Australia.

Abstract 029: Malondialdehyde as a Clinical Indicator for Oxidative Stress and Functional Outcomes in Acute Ischemic Stroke

Introduction Acute Ischemic stroke (AIS) is a leading cause of death and disability worldwide, with Social Isolation (SI) being a contributing factor to worse functional outcomes. The molecular and metabolic changes that occur after AIS are not fully understood. One mechanism known to trigger systemic inflammatory responses and neuronal death characteristic of stroke is the rapid increase in Reactive Oxygen Species (ROS), leading to oxidative stress (OS). New data reports that SI has been shown to increase OS in mouse models. One emerging biomarker able to reliably measure OS is Malondialdehyde (MDA), a reactive carbonyl compound originating from polyunsaturated fatty acid oxidation and lipid peroxidation. Due to its composition, MDA readily reacts with lipid membranes, making it a sensitive OS biomarker. This study assessed MDA levels in the plasma of AIS patients to evaluate its ability to predict long‐term functional outcomes and complications arising from SI. Hypothesis We hypothesized that OS levels correlate with long‐term functional outcomes in AIS patients and varies based on non‐modifiable risk factors such as sex and race. Methods In this study, we used peripheral blood plasma from healthy volunteers (HV, N=24), and from AIS patients (N=27) at 3d and 7d post‐stroke to capture the temporal profile of MDA after injury. Social Isolation was measured utilizing ULCA Loneliness scale and Lubben Social Network Scale collected during patients’ hospitalization. Results AIS patients had an increase in MDA levels compared to the control group, as seen in prior literature. We found a significant positive correlation with age of AIS patients and higher levels of MDA (p<0.05). There was a positive trend with BMI and levels of MDA. As expected, non‐lonely AIS patients had increased levels of MDA when compared to non‐lonely HV (p<0.05). Interestingly, lonely AIS patients had a decrease in MDA when compared to their lonely HV counterparts (p<0.001). Stroke patients with larger social networks had decreased MDA levels. There was no relationship between levels of MDA during hospitalization and functional outcome at 3 months post discharge. Conclusion MDA appears to be a promising biomarker for oxidative stress in AIS patients, with notable associations with age, BMI, and social network and isolation. These findings underscore the complex relationship between OS, social factors, and stroke outcomes. Further research is needed to understand the impact of OS and its correlation with SI so that new treatment plans can be developed for stroke survivors.

Impact of formulation and home storage conditions on the content of furan and derivatives in powdered infant formula

While autoxidation of Polyunsaturated Fatty Acids (PUFAs) is a potential source of furan and its derivatives, the regulatory obligation to enrich powdered infant formulae (PIF) with some of these compounds might raise safety issues. The aim of this study was to investigate the impact of formulation and home storage conditions on the generation of furan and its derivatives in PIF. Furan, 2-methylfuran (2-MF) and 3-methylfuran (3-MF) were monitored by a validated SHS-GC-Q Exactive-Orbitrap MS method in six PIF formulated with high or low concentrations of different PUFAs (ALA, ARA, DHA), pro-oxidants (iron) and anti-oxidants (vitamins) and stored for 21 days under more or less oxidizing home storage conditions, including temperature (19 °C or 40 °C) and oxygen exposure (protected or not from ambient air). For the three compounds, the quality of the measurements in PIF was first confirmed with suitable linearity, limits of quantification, precision and recoveries. In a second step, the impact of the formulation was evaluated on six PIF commercial samples differing significantly in their composition in ALA, ARA, DHA, iron and/or vitamin E and C. While furan was quantifiable (2.8 µg/kg) in only one PIF with high content of DHA and iron and low level of vitamins, 2-MF was only quantifiable in two other PIF which were distinguished by a 15 to 20 % higher ALA content and 3-MF was not detected in any of the six PIF studied. In a third step, the effect of storage conditions was studied on the six PIF and the increase in storage temperature to 40 °C led to an increase of up to 33 % in the 2-MF concentration in the two PIF formulations where it was quantifiable. Nevertheless, the estimation of the Margin of Exposure (MOE) showed that the risk related to furan and its derivatives could be ruled out regardless of the formulation or storage conditions. Finally, in order to explore other derivatives and to investigate the mechanisms involved in the generation of furan compounds in PIF, a suspect screening approach was implemented on the SHS-GC-Q Exactive-Orbitrap MS data. It made it possible on the one hand to point out two additional furan derivatives in PIF, 2-ethylfuran and 2-pentylfuran. On the other hand, it enabled to discuss the oxidation pathways involved in the generation of furan compounds in PIF from profiling of known PUFA oxidation markers also detected in the samples.

Stress biomarker response in Aporrectodea caliginosa earthworms exposed to single and combined pesticide treatments (Prosaro and Decis).

This study aims to assess the impact of two pesticides commonly used in Algeria (Prosaro XRT and Decis 25 EC), as well as their combinations at recommended doses, on a non-target species bioindicator of soil pollution, the earthworm Aporrectodea caliginosa, using physiological (mortality and growth) and biochemical parameters (proteins, glutathione, catalase activity and glutathione S-transferase, acetylcholine esterase, lipoxygenase). The recommended dose and its double were tested individually and in combination for this. It should be noted that the protocol used and the initial concentrations selected are the same as those used in the field. After 7 and 14 days (7D/14D) of exposure, all dosages were administered. Our findings show that the pesticides tested had no effect on earthworm survival. However, a significant decrease in their growth rates depending on the different concentrations was observed for the different treatments over the entire exposure period of 7 or 14 D. The greatest reductions (31.62%, 35.04%) are reported after 14D for the high concentrations of Decis alone (D2) as well as for the combined treatment Prosaro/Decis (P2/D2). At the same time, an increase in total protein contents (more than 50% after 14D) as well as a decrease in acetylcholine esterase activity were reported for all treatments. We were also able to identify the induction of oxidative stress after xenobiotic exposure, which is more pronounced at the end of the treatment (14D), resulting in the stimulation of the antioxidant system (gluthione, glutathione S-transférase, catalase) as well as the induction of lipoxygenase, which is responsible for the oxidation of polyunsaturated fatty acids as well as the generation of reactive oxygen species (ROS) involved in the inflammatory phenomenon. Finally, it turns out that the species Aporrectodea caliginosa is sensitive to the different concentrations applied, even those used in the open field, and that Decis (deltamethrin) seems to be more toxic than Prosaro and that the combinaison P2/D2 is as toxic as Decis alone (D2).

FGF21 inhibits ferroptosis caused by mitochondrial damage to promote the repair of peripheral nerve injury.

Ferroptosis is a new type of cell death characterized by lipid peroxidation and iron dependency, representing an emerging disease regulation mechanism. The limited understanding of ferroptosis in peripheral nerve injury (PNI) complicates the management of such injuries. Mitochondrial dysfunction, which contributes to ferroptosis, further exacerbates the challenges of peripheral nerve repair. In this study, we established an in vitro model of Schwann cells model treated with TBHP and an in vivo sciatic nerve crush injury model in rats. These models were used to investigate the effects of fibroblast growth factor 21 (FGF21) on PNI, both in vitro and in vivo, and to explore the potential mechanisms linking injury-induced ferroptosis and mitochondrial dysfunction. Our findings reveal that PNI triggers abnormal accumulation of lipid reactive oxygen species (ROS) and inactivates mitochondrial respiratory chain complex III, leading to mitochondrial dysfunction. This dysfunction catalyzes the oxidation of excessive polyunsaturated fatty acids, resulting in antioxidant imbalance and loss of ferroptosis suppressor protein 1 (FSP1), which drives lipid peroxidation. Additionally, irregular iron metabolism, defective mitophagy, and other factors contribute to the induction of ferroptosis. Importantly, we found that FGF21 attenuates the abnormal accumulation of lipid ROS, restores mitochondrial function, and suppresses ferroptosis, thus promoting PNI repair. Notably, glutathione peroxidase 4 (GPX4), a downstream target of nuclear factor E2-related factor 2 (Nrf2), and the ERK/Nrf2 pathway are involved in the regulation of ferroptosis by FGF21. FGF21 promotes peripheral nerve repair by inhibiting ferroptosis caused by mitochondrial dysfunction. Therefore, targeting mitochondria and ferroptosis represents a promising therapeutic strategy for effective PNI repair.

Oil polyunsaturated fatty acid composition but not tocopherol levels determine oxylipin formation in plant and algae oils during pan-frying

The oxidation of linoleic acid (LA) and α-linolenic acid (ALA) in plant oils results in primary oxidation products known as oxylipins. It is not known whether the mechanisms of oxidation are driven primarily by oil polyunsaturated fatty acid (PUFA) composition (i.e., more double bonds resulting in more rapid oxidation) or antioxidant (tocopherol) content. The present study addressed this unknown by measuring the effects of pan-frying on LA- and ALA-derived oxylipin concentrations in plant and algae oils with different baseline fatty acid and tocopherol concentrations. Oxylipins, free fatty acids and tocopherols were quantified in algae, olive, corn, canola, and soybean oils before and after 30 minutes of pan-frying. Fatty acid epoxides and hydroxides of LA or ALA were significantly elevated after pan-frying, whereas fatty acid diols were reduced. The level of change in oxylipins was lower in low-PUFA algae and extra virgin olive oils compared to soybean, canola and corn oils (high in PUFAs). Tocopherols decreased significantly after 30 minutes of pan-frying, particularly in oils with low PUFA composition. Minor changes were observed in free fatty acids. Our findings demonstrate that oil PUFA composition is a greater determinant of lipid oxidation than tocopherol content, and that PUFAs in high LA or ALA oils may spare tocopherol oxidation by acting as free radical scavengers.

The Effect of Prawns Shell Carotenoprotein Insertion on the Quality and Oxidative Stability of Tuna Eye Oil

The oxidation of polyunsaturated fatty acids (PUFAs) reduces the nutritional value of fish oil supplements and poses health risks due to the formation of free radicals and oxidative compounds. Consequently, preventing or minimizing oxidation in these supplements is a critical concern in the production industry. Tuna eye (TE) oil, similar to other fish oils, is highly prone to oxidation, leading to the need for antioxidant enhancement. Carotenoprotein, rich in astaxanthin from shrimp shells, is a powerful natural antioxidant that can potentially stabilize PUFAs in TE oil, but the application to TE oil has not been previously explored. Therefore, this study aimed to evaluate the effect of shrimp shell-derived carotenoprotein on the quality and oxidative stability of TE oil during storage. The proximate composition of tuna eye and shrimp by-products was analyzed during the investigation process. Initial TE oil and TE oil with added carotenoprotein were assessed for free fatty acid content, acid value, peroxide value, p-anisidine value, total oxidation value, and heavy metal content. Carotenoprotein was evaluated for its color and antioxidant activity. The TE oil was combined with 0.4%, 0.6%, and 0.8% (v/v) concentrations of carotenoprotein and examined for stability using the Schaal oven test method at 40°C. The variations in these concentrations were systematically selected to determine potential concentration-dependent effects on TE oil oxidative stability. The results showed that on day 60 of TE oil storage at room temperature, oxidative degradation was significantly influenced by carotenoprotein concentration. Free fatty acids increased to 1.39%, while the values of acid, peroxide, anisidine, and total oxidation identified at the 0.4, 0.6, and 0.8% concentrations were 1.61, 1.50, and 1.24 mg KOH/kg, 18.87, 15.98, and 13.29 meq/kg, 10.80, 11.40, and 9.70 meq/kg, as well as 48.54, 43.36, and 36.28 meq/kg, respectively. Moreover, 0.8% carotenoprotein addition was found to effectively prevent TE oil deterioration compared to the control group.

Effect of fatty acid composition on the volatile compounds of pasteurized milk during low-temperature storage

The change in milk fat during storage greatly influences its flavor. This study investigates the effect of fatty acid composition on milk flavor by analyzing volatile compounds in pasteurized whole milk (PWM) and pasteurized skim milk (PSM) during storage at 4 °C. 33 types of volatile compounds were detected and the content of ketones was highest, followed by esters and aldehydes. Based on variable importance in projection and relative odor activity value, 2-hexenal dimer, acetic acid ethyl ester dimer, acetic acid ethyl ester, and butanal were identified as the key differential volatile compounds. These compounds were found in higher concentrations in PWM than in PSM, indicating a close relationship with the changes in the fatty acid composition of milk fat. Among 11 fatty acids detected in PWM, the content of saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) decreased by 0.69 % and 49.1 %, respectively, while the content of monounsaturated fatty acids increased by 46.8 % during 15 days storage, which suggests that the oxidation of SFA and PUFA contributed more to the volatile compound formation. Correlation analysis between fatty acid composition and volatile compounds found that fatty acid C18:2 and C16:0 were strongly associated for 2-hexenal, acetic acid ethyl ester, and butanal. These fatty acids were mainly derived from neutral lipids or phospholipids. These findings provide a new perspective for the formation pathway of milk flavor.

Isoniazid Derivatives as Potential Lipoxygenase‐15 Inhibitors: In‐vitro and In‐silico Studies

AbstractThe enzymatic oxidation of polyunsaturated fatty acids, particularly arachidonic acid, produces important lipid mediators such as leukotrienes and prostaglandins, which are critical for triggering inflammatory cascades in the body. The enzyme lipoxygenase‐15 (LOX‐15) plays a crucial role in the oxygenation of unsaturated fatty acids. Targeting this enzyme for inhibition is essential for diminishing inflammation and averting numerous potentially fatal diseases. Therefore, the inhibitory activity of a series of isoniazid derivatives, selected from our in‐house library, was assessed against LOX‐15 by employing both in vitro and in silico methods. Among the 23 compounds evaluated, 15 showed activity in vitro. Notably, compound 7 was the most effective, demonstrating an IC50 value of 1.4±0.1 μM while the standard inhibitor, NDGA, showed an inhibition at 9.4±0.6 μM. These compounds were found to competitively inhibit LOX‐15, with Ki values ranging from 1.2–7.1 μM. Molecular docking was utilized to investigate the intermolecular interactions among the active compounds. The thermodynamic stability of the compound 7 and NDGA in complex with LOX‐15 was verified through 100 ns of molecular dynamics simulations. Post‐simulation analyses involved RMSD, RMSF, RoG, free energy landscape, principal component analysis, and dynamic cross‐correlation matrix. Compound 7 and NDGA had MM/GBSA binding energies of −54.14±2.55 kcal/mol and −35.24±3.23 kcal/mol, respectively. The study underscores the significant potential of isoniazid derivatives in LOX‐15 inhibition and their role in managing inflammatory diseases.

Shelf Life Enhancement of Structured Lipids Rich in Omega-3 Fatty Acids Using Rosemary Extract: A Sustainable Approach.

This study investigates the efficacy of rosemary extract (RE) in stabilizing structured lipids (SL) developed using perilla seed oil (PSO) and palmolein (PO) under accelerated storage conditions. The oil samples, comprising PSO, Blend, and SL formulations with and without RE (1500 ppm) and BHT (200 ppm), were studied for their storage stability during a 30 day storage period at 65 °C, with the analysis carried out at 6 day intervals. Oxidative properties were comprehensively assessed, including both physical attributes (color, viscosity, and refractive index) and chemical parameters (peroxide value, free fatty acid (FFA), p-anisidine value, TOTOX value, conjugated dienes, and trienes). The results demonstrated that RE-enriched oil samples exhibited significantly higher oxidative stability (p < 0.05) compared to the control group. SL added with 1500 ppm of RE exhibited notable enhancements in quality parameters, showcasing reductions in FFA, TOTOX value, conjugated diene, and triene value by 44.01%, 35.42, 39.03, and 47.36, respectively, when compared to SL without any antioxidant. The RE at 1500 ppm concentration showed a similar effect as the synthetic antioxidant BHT at 200 ppm. Also, the RE demonstrated potent inhibition of the oxidation of polyunsaturated fatty acids, thereby contributing to the improved oxidative stability of the SLs. Furthermore, SL with RE also exhibited reduced degradation of the tocopherol content and total phenolic content during the storage period. Principal component analysis demonstrated that SL and blend followed similar oxidative characteristics as they fell within the same quadrant. These findings underscore RE as a potent source of antioxidants capable of scavenging free radicals and enhancing the oxidative stability of omega-3 fatty acid-rich SLs.

Collective Total Synthesis of Ecklonialactones, Eiseniachlorides and Analogs.

Ecklonialactones, Eiseniachlorides, and Egregiachlorides are synthesized in living organisms via the lipoxygenase-mediated oxidation of polyunsaturated fatty acids. Originally isolated and identified from brown seaweed (Ecklonia stolonifera, Eisenia bicyclis, and Egregia menziesii), and later replicated on milligram scale through chemical synthesis, the full biological activities of these compounds remain to be elucidated. To bridge this gap in knowledge, we propose a unified methodology to synthesize the 14-membered macrocyclic structures of Ecklonialactones, Eiseniachlorides and analogs using a versatile and convergent approach. This study delineates the synthesis of Ecklonialactone A, B, C, D, and Eiseniachlorides A and B, as well as ent-Ecklonialactone B, 16-epi-Ecklonialactone B and 12,13-diepi-Ecklonialactone B.

A multifunctional nanoplatform for chemotherapy and nanocatalytic synergistic cancer therapy achieved by amplified lipid peroxidation

Traditional cancer chemotherapy suffers from low efficacy and severe side effects, limiting its use as a first-line treatment. To address this issue, we investigated a novel way to induce lipid peroxidation (LPO), which plays an essential role in ferroptosis and may be useful against cancer cells and tumors. In this study, a pH-responsive synergistic cancer therapy nanoplatform was prepared using CaCO3 co-loaded with oleanolic acid (OA) and lipoxygenase (LOX), resulting in the formation OLCaP NP. This nanoplatform exhibited good drug release properties in an acidic tumor environment owing to the presence of CaCO3. As a result of acidic stimulation at tumor sites, the OLCaP NP released OA and LOX. OA, a chemotherapeutic drug with anticancer activity, is already known to promote the apoptosis of cancer cells, and LOX is a natural enzyme that catalyzes the oxidation of polyunsaturated fatty acids, leading to the accumulation of lipid peroxides and promoting the apoptosis of cancer cells. More importantly, OA upregulated the expression of acyl-coenzyme A synthetase long-chain family member 4 (ACSL4), which promoted enzyme-mediated LPO. Based on our combined chemotherapy and nanocatalytic therapy, the OLCaP NP not only had remarkable antitumor ability but also upregulated ACSL4 expression, allowing further amplification of LPO to inhibit tumor growth. These findings demonstrate the potential of this nanoplatform to enhance the therapeutic efficacy against tumors by inducing oxidative stress and disrupting lipid metabolism, highlighting its clinical potential for improved cancer treatment. Statement of significanceThis study presents a novel nanoplatform that combines oleanolic acid (OA), a chemotherapeutic drug, and lipoxygenase (LOX), which oxidizes polyunsaturated fatty acids to trigger apoptosis, for targeted cancer therapy. Unlike traditional treatments, our nanoplatform exhibits pH-responsive drug release, specifically in acidic tumor environments. This innovation enhances the therapeutic effects of OA and LOX, upregulating acyl-CoA synthetase long-chain family member 4 expression and amplifying lipid peroxidation to promote tumor cell apoptosis. Our findings significantly advance the existing literature by demonstrating a synergistic approach that combines chemotherapy and nanocatalytic therapy. The scientific impact of this work lies in its potential to improve cancer treatment efficacy and specificity, offering a promising strategy for clinical applications and future research in cancer therapy.

Bcl-xL regulates radiation-induced ferroptosis through chaperone-mediated autophagy of GPX4 in tumor cells

ObjectiveTo investigate the role and the molecular mechanisms of apoptotic signaling in ferroptosis to regulate tumor radiosensitivity. MethodsReactive oxygen species (ROS) and lipid peroxide levels were detected in Mouse embryonic fibroblasts(MEFs) with Bcl-xL or Mcl-1 deficiency induced by erastin. Colony formation, ROS, lipid peroxidation and the transcription/translation levels of PTGS2 were measured in Bcl-xL knockdown tumor cells induced by 5 ​Gy γ-rays or co-treated with ferrostatin-1 (Ferr-1). The protein levels of LPCAT3, ACSL4 and PEBP1 in Bcl-xL knockout MEF cells were evaluated in Bcl-xL knockout MEF cells post-radiation. Moreover, the interaction of heat shock protein 90 (HSP90) with Bcl-xL, GPX4, or LAMP2A was detected by protein mass spectrometry and immunoprecipitation assays. ResultsManipulating Bcl-xL levels facilitated radiation-induced ferroptosis by augmenting the enzymatic oxidation of polyunsaturated fatty acids (PUFAs) and enhancing chaperone-mediated autophagy (CMA) of glutathione peroxidase 4 (GPX4) (MEF cell line: t=4.540, P＜0.01; A549 ​cell line: t=56.16, P＜0.0001; t=4.885, P＜0.01; HCT116 ​cell line: t=14.75, P＜0.01; t=7.363, P＜0.05). Downregulating Bcl-xL expression promoted the activity of acyl-CoA synthetase long-chain family member 4 (ACSL4), thus increasing the enzymatic oxidation of PUFAs (t=4.258, P＜0.01). Moreover, depletion of Bcl-xL expedited the CMA process targeting GPX4 by facilitating the association of GPX4 with heat shock protein 90 (HSP90) and LAMP2A following radiation exposure. Subsequent degradation of GPX4 led to the accumulation of lipid peroxides, ultimately triggering ferroptosis. ConclusionsOur study provides initial insights into the regulatory role of Bcl-xL in ferroptosis and underscores the potential of targeting Bcl-xL as a promising therapeutic strategy for cancer by modulating both apoptotic and ferroptotic pathways.

Identification of the Thermal Activation Network in Human 15-Lipoxygenase-2: Divergence from Plant Orthologs and Its Relationship to Hydrogen Tunneling Activation Barriers.

The oxidation of polyunsaturated fatty acids by lipoxygenases (LOXs) is initiated by a C-H cleavage step in which the hydrogen atom is transferred quantum mechanically (i.e., via tunneling). In these reactions, protein thermal motions facilitate the conversion of ground-state enzyme-substrate complexes to tunneling-ready configurations and are thus important for transferring energy from the solvent to the active site for the activation of catalysis. In this report, we employed temperature-dependent hydrogen-deuterium exchange mass spectrometry (TDHDX-MS) to identify catalytically linked, thermally activated peptides in a representative animal LOX, human epithelial 15-LOX-2. TDHDX-MS of wild-type 15-LOX-2 was compared to two active site mutations that retain structural stability but have increased activation energies (Ea) of catalysis. The Ea value of one variant, V427L, is implicated to arise from suboptimal substrate positioning by increased active-site side chain rotamer dynamics, as determined by X-ray crystallography and ensemble refinement. The resolved thermal network from the comparative Eas of TDHDX-MS between wild-type and V426A is localized along the front face of the 15-LOX-2 catalytic domain. The network contains a clustering of isoleucine, leucine, and valine side chains within the helical peptides. This thermal network of 15-LOX-2 is different in location, area, and backbone structure compared to a model plant lipoxygenase from soybean that exhibits a low Ea value of catalysis compared to the human ortholog. The presented data provide insights into the divergence of thermally activated protein motions in plant and animal LOXs and their relationships to the enthalpic barriers for facilitating hydrogen tunneling.

Abstract 4451: Regulation of lipid metabolism and ferroptosis by DAXX

Abstract Intracellular lipid production in cancer cells supplies lipids to synthesize cell membranes and signaling molecules during rapid cell proliferation and tumor growth. Cancer cells also utilize fatty acid oxidation (FAO) to generate ATP to meet their energy demand. Notably, lipid metabolites can inhibit and trigger ferroptosis due to iron-dependent oxidation of polyunsaturated fatty acids (PUFAs). Therefore, identifying regulators that maintain the intricate balance of lipid biosynthesis required for cell proliferation and survival is critical in cancer biology and therapy. Lipid metabolism is regulated by two oncogenic signaling pathways: the RAS-RAF-MEK-MAPK and the mammalian target of rapamycin (mTOR) pathways. About 30% of all cancers harbor constitutively active mutations in KRAS, HRAS, or NRAS, resulting in hyperactive RAS-RAF-MEK-MAPK signaling to drive tumorigenesis, metastatic progression, immune evasion, and resistance to therapy. KRAS regulates lipid uptake, lipid synthesis, and FAO. mTOR is a serine/threonine kinase acting as a key intracellular signaling hub to regulate nutrient homeostasis, metabolism, protein synthesis, and autophagy. The mTORC1 complex promotes lipogenesis. The RAS and mTOR signaling pathways exhibit both positive and negative cross-regulation. The coordinated activity of both pathways is critical to sustained tumor growth. Notably, mTORC1 signaling inhibition enhances RAS-RAF-MEK-MAPK signaling to promote cancer cell survival and proliferation. Furthermore, constitutive mTORC1 signaling induces cell death when the supply of unsaturated FAs is limited. However, the molecular link for coordinating the activity of the RAS and mTOR signaling pathways remains poorly defined. Death domain-associated protein (DAXX) is essential for mouse embryonic development and has ill-defined pro-cell survival functions. Our lab has a long-standing interest in deciphering DAXX’s complex biological functions. Our recent study shows that DAXX drives tumorigenesis by promoting lipogenic gene expression and lipid synthesis through interacting with sterol regulatory element-binding proteins SREBP1 and SREBP2 (SREBP1/2) (Mahmud et al., 2023, PMID 37045819). Unexpectedly, our new data reveal that DAXX inhibits ferroptosis. Significantly, phosphorylation via RAS signaling appears to regulate DAXX’s activity in lipid synthesis and resistance to ferroptosis. Remarkably, disruption of DAXX-mediated lipid synthesis potentiates ferroptosis due to mTORC1 activity. Based on these observations, we propose that stimulated by the RAS-RAF-MEK-MAPK oncogenic signaling, DAXX promotes tumorigenesis through upregulating genes for lipid synthesis and resistance to ferroptosis, and that the lack of DAXX-mediated lipid synthesis leads to sensitization of cells to ferroptosis due to mTORC1’s proliferative effects. (Supported by FDOH grant 23K03). Citation Format: Wenlin Yang, Nikee Awasthee, Qi Chen, Seth Hale, Daiqing Liao. Regulation of lipid metabolism and ferroptosis by DAXX [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4451.

The Potential of Acorn Extract Treatment on PUFAs Oxidative Stability: A Case Study on Fish Cooking Wastewater.

Fish byproducts are valuable sources of Ω-3 polyunsaturated fatty acids (PUFAs). Their valorization potentially alleviates pressure on this sector. This study uses a circular economy approach to investigate the oil fraction from sardine cooking wastewater (SCW). Analysis of its fatty acid (FA) profile revealed promising PUFA levels. However, PUFAs are highly susceptible to oxidation, prompting the exploration of effective and natural strategies to replace synthetic antioxidants and mitigate their associated risks and concerns. An antioxidant extract from acorn shells was developed and evaluated for its efficacy in preventing oxidative degradation. The extract exhibited significant levels of total phenolic compounds (TPC: 49.94 and 22.99 mg TAE or GAE/g DW) and antioxidant activities (ABTS: 72.46; ORAC: 59.60; DPPH: 248.24 mg TE/g DW), with tannins comprising a significant portion of phenolics (20.61 mg TAE/g DW). LC-ESI-UHR-QqTOF-MS identified ellagic acid, epicatechin, procyanidin B2 and azelaic acid as the predominant phenolic compounds. The extract demonstrated the ability to significantly reduce the peroxide index and inhibit PUFA oxidation, including linoleic acid (LA), eicosapentaenoic (EPA), and docosahexaenoic acid (DHA). This approach holds promise for developing stable, functional ingredients rich in PUFAs. Future research will focus on refining oil extraction procedures and conducting stability tests towards the development of specific applications.

Dielectric barrier discharge cold plasma collaborated with coconut exocarp flavonoids: A promising technology for oyster preservation under refrigerated storage

The effect of coconut exocarp flavonoids (CF) combined with cold plasma (CP) treatment on oyster preservation during refrigerated storage was investigated. It was observed oyster without preservation suffered the most serious microbial spoilage and chemical changes during storage. CP significantly inhibited spoilage bacteria, inactivated endogenous lipid hydrolases and LOX activities (P < 0.05). Simultaneously, it caused undesirable polyunsaturated fatty acid (PUFA) oxidation and glycerophospholipid species depletion, while extended CP processing aggravated them. CF marinating collaborated with 10 min CP exposure exhibited least bacterial count, total volatile base nitrogen, peroxide and thiobarbituric acid values with 5.16 logCFU/g, 19.62 mg/100 g, 22.05 meq/kg and 801.8 μg MDAeq/kg, respectively, thus extending the shelf-life. Moreover, it enhanced the inhibition ability toward LOX activity and alleviated PUFA oxidation triggered by CP. Therefore, the collaboration of CF and CP serve as effective technology for oyster preservation, while the CP processing time should be optimized from the nutritional value perspective.

ACOX1 deficiency-induced lipid metabolic disorder facilitates chronic interstitial fibrosis development in renal allografts

Chronic interstitial fibrosis presents a significant challenge to the long-term survival of transplanted kidneys. Our research has shown that reduced expression of acyl-coenzyme A oxidase 1 (ACOX1), which is the rate-limiting enzyme in the peroxisomal fatty acid β-oxidation pathway, contributes to the development of fibrosis in renal allografts. ACOX1 deficiency leads to lipid accumulation and excessive oxidation of polyunsaturated fatty acids (PUFAs), which mediate epithelial–mesenchymal transition (EMT) and extracellular matrix (ECM) reorganization respectively, thus causing fibrosis in renal allografts. Furthermore, activation of Toll-like receptor 4 (TLR4)-nuclear factor kappa-B (NF-κB) signaling induced ACOX1 downregulation in a DNA methyltransferase 1 (DNMT1)-dependent manner. Overconsumption of PUFA resulted in endoplasmic reticulum (ER) stress, which played a vital role in facilitating ECM reorganization. Supplementation with PUFAs contributed to delayed fibrosis in a rat model of renal transplantation. The study provides a novel therapeutic approach that can delay chronic interstitial fibrosis in renal allografts by targeting the disorder of lipid metabolism.

From MS/MS library implementation to molecular networks: Exploring oxylipin diversity with NEO-MSMS

Oxylipins, small polar molecules derived from the peroxidation of polyunsaturated fatty acids (PUFAs), serve as biomarkers for many diseases and play crucial roles in human physiology and inflammation. Despite their significance, many non-enzymatic oxygenated metabolites of PUFAs (NEO-PUFAs) remain poorly reported, resulting in a lack of public datasets of experimental data and limiting their dereplication in further studies. To overcome this limitation, we constructed a high-resolution tandem mass spectrometry (MS/MS) dataset comprising pure NEO-PUFAs (both commercial and self-synthesized) and in vitro free radical-induced oxidation of diverse PUFAs. By employing molecular networking techniques with this dataset and the existent ones in public repositories, we successfully mapped a wide range of NEO-PUFAs, expanding the strategies for annotating oxylipins, and NEO-PUFAs and offering a novel workflow for profiling these molecules in biological samples.

Optimization of Ultrasound-Assisted Microwave Encapsulation of Peanut Oil in Protein-Polysaccharide Complex.

Peanut oil (Arachis hypogaea L.) is a rich source of unsaturated fatty acids. Its consumption has been reported to have biological effects on human health. Unsaturated, especially polyunsaturated fatty acids (PUFA) found in peanut oil are highly susceptible to oxidation, leading to the formation of harmful compounds during processing and storage. The aim of this study is to prevent the oxidation of peanut oil PUFA by encapsulation in a protein-polysaccharide complex using microwave drying. The combined effect of corn starch (CS) and whey protein isolate (WPI) was evaluated for ultrasound-assisted microwave encapsulation of peanut oil to prevent oxidative degradation. The effect of independent parameters, viz. CS:WPI mass ratio (1:1 to 5:1), lecithin mass fraction (0-5 %), ultrasonication time (0-10 min) and microwave power (150-750 W) on the encapsulation of peanut oil was evaluated using response surface methodology (RSM). The process responses, viz. viscosity and stability of the emulsion, encapsulation efficiency, peroxide value, antioxidant activity, free fatty acids (FFA), moisture, angle of repose and flowability (Hausner ratio (HR) and Carr's Index (CI)) were recorded and analysed to optimize the independent variables. The viscosity of all emulsions prepared for encapsulation by ultrasonication ranged from 0.0069 to 0.0144 Pa·s and more than 90 % of prepared combinations were stable over 7 days. The observed encapsulation efficiency of peanut oil was 21.82-74.25 %. The encapsulation efficiency was significantly affected by the CS:WPI mass ratio and ultrasonication. The peroxide value, antioxidant activity and FFA ranged from 1.789 to 3.723 mg/kg oil, 19.81-72.62 % and 0.042-0.127 %, respectively. Physical properties such as moisture content, angle of repose, HR and CI were 1.94-8.70 %, 46.5-58.3°, 1.117-1.246 and 10.48-22.14 %, respectively. The physical properties were significantly affected by surface properties of the capsules. The higher efficiency (74.25 %) of peanut oil encapsulation was achieved under optimised conditions of CS:WPI mass ratio 1.25, 0.25 % lecithin, 9.99 min ultrasonication and 355.41 W microwave power. The results of this work contribute to the fields of food science and technology by providing a practical approach to preserving the nutritional quality of peanut oil and improving its stability through encapsulation, thereby promoting its potential health benefits to consumers and applications in various industries such as dairy and bakery.