Lipoxygenase Research Articles

A review on the relationship between Arachidonic acid 15-Lipoxygenase (ALOX15) and diabetes mellitus.

Arachidonic acid 15-lipoxygenase (ALOX15), as one of the lipoxygenase family, is mainly responsible for catalyzing the oxidation of various fatty acids to produce a variety of lipid components, contributing to the pathophysiological processes of various immune and inflammatory diseases. Studies have shown that ALOX15 and its related products are widely distributed in human tissues and related to multiple diseases such as liver, cardiovascular, cerebrovascular diseases, diabetes mellitus and other diseases. Diabetes mellitus (DM), the disease studied in this article, is a metabolic disease characterized by a chronic increase in blood glucose levels, which is significantly related to inflammation, oxidative stress, ferroptosis and other mechanisms, and it has a high incidence in the population, accompanied by a variety of complications. Figuring out how ALOX15 is involved in DM is critical to understanding its role in diseases. Therefore, ALOX15 inhibitors or combination therapy containing inhibitors may deliver a novel research direction for the treatment of DM and its complications. This article aims to review the biological effect and the possible function of ALOX15 in the pathogenesis of DM.

SAT071 Inhibition Of 12 Lipoxygenase In A Humanized Mouse Model Of Type 1 Diabetes Delays Progression Of Hyperglycemia

Abstract Disclosure: T. Nargis: None. A. Chakraborty: None. K. Figatner: None. D. Maloney: None. M. Boxer: None. S.A. Tersey: None. R.G. Mirmira: None. Type 1 diabetes (T1D) is an autoimmune disorder characterized by islet inflammation (insulitis). We have recently shown that a key mediator of inflammatory signaling in the islet beta cell is the enzyme 12-lipoxygenase (12-LOX), which generates proinflammatory eicosanoids that augment dysfunctional insulin secretion and beta-cell visibility to the immune system. Whereas inhibition of 12-LOX offers an opportunity to modify T1D progression by altering how the beta cell responds to insulitis, a barrier to testing inhibitors in preclinical models is the specificity of next generation inhibitors toward the human enzyme. To generate a preclinical platform for the study of human-specific 12-LOX inhibitors, we developed a mouse model in which the mouse-equivalent Alox15 coding region was replaced with the human ALOX12 gene, while retaining the mouse upstream control region. These mice (hALOX12) were developed on both the C57BL/6J and NOD genetic backgrounds, then subjected to treatment with the human 12-LOX inhibitor VLX-1005 to evaluate diabetes progression. C57BL/6J-wildtype and C57BL/6J-hALOX12 mice were confirmed to express exclusively mouse Alox15 and human ALOX12, respectively, using RNA isolated from islets. To test susceptibility to toxin-induced diabetes, C57BL/6J-wildtype and C57BL/6J-hALOX12 were subjected to multiple low-dose streptozotocin (STZ) to induce diabetes. Both wildtype and humanized mice exhibited gradual and equivalent hyperglycemia (within 25 days) following STZ injection. Following intraperitoneal VLX-1005 therapy (30 mg/kg), whereas C57BL/6J-wildtype mice developed diabetes (with a delay of 10 days) following STZ, C57BL/6J-hALOX12 mice showed complete protection against STZ-induced diabetes and exhibited significantly better glucose tolerance compared to vehicle- or VLX-1005-injected wildtype controls and vehicle-injected C57BL/6J-hALOX12 mice. Next, hALOX12 mice were backcrossed onto the NOD.ShiltJ background model of autoimmune T1D. NOD-hALOX12 mice received either vehicle or VLX-1005 (30 mg/kg) orally during the prediabetic phase (6-10 weeks of age) and were followed for diabetes incidence. Mice receiving VLX-1005 showed a significant delay with only 30% of female and 7% of male mice developing diabetes over 25 weeks of age. Pancreatic sections from the mice treated with VLX-1005 showed reduced insulitis and increased beta cell mass compared to vehicle controls. In summary, the hALOX12 mouse model serves as a preclinical translational platform to interrogate effects of next generation 12-LOX inhibitors and demonstrates the potential of VLX-1005 to modify T1D disease progression. Presentation: Saturday, June 17, 2023

NMR Structure Elucidation and Molecular Modeling of Lipoxygenase and Cholinesterase Inhibiting Steroids from Hypericum oblongifolium

Abstract: Hypericum oblongifolium is a potent source of bioactive constituents. A series of pharmacological properties, ranging from wound healing and antiseptic to antiviral, anti-inflammatory, anticancer, ethanol intake inhibition, and apoptosis-inducing activities have been associated with this plant. The current research project was designed to investigate the new secondary metabolites in H. oblongifolium having excellent pharmaceutical potential. In the present investigation two new cholestane-type steroids, hyperinoate A (1) and hyperinoate B (2) were isolated from a chloroform soluble fraction of the whole plant of H. oblongifolium. Structures of isolated new compounds were elucidated based on spectroscopic data including 1D (1HNMR, 13CNMR) and 2D (HMBC, COSY, NOESY) NMR and mass spectrometry (EIMS, HREIMS) data. After structure elucidation, new compounds were named 6α-hydroxy-14α-methyl Cholestan-3-yl-acetate and 6α,25-dihydroxy-14α-methyl Cholestane-3-yl-acetate. Both steroids showed promising inhibitory activity against lipoxygenase (LOX) and acetylcholinesterase (AChE) enzymes. Especially hyperinoate A (1) inhibited the lipoxygenase (LOX) enzyme with IC50 41.7± 0.15 µM whereas Baicalein (positive control) had IC50 42.3 ± 0.20 µM. Similarly, Hyperinoate B (2) (56.3 ± 0.33 µM) showed higher inhibition than Galantamine (positive control) 53.8 ± 0.54 µM. These results were validated with in-silico molecular docking investigations. The greater binding affinity of hyperinoate A (1) (-9.2 Kcal/mol) against LOX-5(PDB ID 3V99) showed higher inhibition as compared to baicalein (positive control) (-7.7 Kcal/mol). The binding affinities of hyperinoate B (2) (-10.5 Kcal/mol) were close to galantamine (-10.6 Kcal/mol). All in-vitro and in-silico results revealed that both newly isolated compounds showed moderate inhibition against lipoxygenase (LOX) and acetylcholinesterase (AChE) enzymes.

Arbuscular mycorrhizal fungi as an effective approach to enhance the growth and metabolism of soybean plants under thallium (TI) toxicity

Thallium (TI) is a toxic metal that can trigger harmful impacts on growth and metabolism of plants. Utilizing arbuscular mycorrhizal fungi (AMF) proves to be an effective strategy for alleviating heavy metal toxicity in plants. To this end, AMF were applied to mitigate TI toxic effects on the growth, primary and secondary metabolism of soybean plants. Here, TI stress inhibited the growth and photosynthetic parameters of soybean plants. It also increased the oxidative damage as demonstrated by increased levels of oxidative markers, (MDA and lipoxygenase (LOX) activity). However, AMF could mitigate the reduction in growth and photosynthesis induced by TI, as well as the induction of oxidative damage. To overcome TI toxicity, AMF increased the levels and metabolism of osmolytes such as proline in soybean plants. This was in line with the increased activities of key enzymes that involved in proline biosynthesis (e.g., P5CS (pyrroline-5-carboxylate synthetase), P5CR (pyrroline-5-carboxylate reductase) and OAT (ornithine aminotransferase) under the AMF and/or TI treatments. Furthermore, soybean plants could benefit from the synergism between AMF and TI to enhance the contents of individual (e.g., spermine and spermidine) and total polyamines as well as their metabolic enzymes (e.g., arginine decarboxylase and ornithine decarboxylase). Overall, the combined application of AMF emerges as a viable approach for alleviating TI toxicity in soybean plants.

Self-fueling ferroptosis-inducing microreactors based on pH-responsive Lipiodol Pickering emulsions enable transarterial ferro-embolization therapy.

Lipiodol chemotherapeutic emulsions remain one of the main choices for the treatment of unresectable hepatocellular carcinoma (HCC) via transarterial chemoembolization (TACE). However, the limited stability of Lipiodol chemotherapeutic emulsions would lead to rapid drug diffusion, which would reduce the therapeutic benefit and cause systemic toxicity of administrated chemotherapeutics. Therefore, the development of enhanced Lipiodol-based formulations is of great significance to enable effective and safe TACE treatment. Herein, a stable water-in-oil Lipiodol Pickering emulsion (LPE) stabilized by pH-dissociable calcium carbonate nanoparticles and hemin is prepared and utilized for efficient encapsulation of lipoxygenase (LOX). The obtained LOX-loaded CaCO3&hemin-stabilized LPE (LHCa-LPE) showing greatly improved emulsion stability could work as a pH-responsive and self-fueling microreactor to convert polyunsaturated fatty acids (PUFAs), a main component of Lipiodol, to cytotoxic lipid radicals through the cascading catalytic reaction driven by LOX and hemin, thus inducing ferroptosis of cancer cells. As a result, such LHCa-LPE upon transcatheter embolization can effectively suppress the progression of orthotopic N1S1 HCC in rats. This study highlights a concise strategy to prepare pH-responsive and stable LPE-based self-fueling microreactors, which could serve as bifunctional embolic and ferroptosis-inducing agents to enable proof-of-concept transarterial ferro-embolization therapy of HCC.

Selenium-Priming mediated growth and yield improvement of turnip under saline conditions

Salt toxicity is one of the foremost environmental stresses that declines nutrient uptake, photosynthetic activity and growth of plants resulting in a decrease in crop yield and quality. Seed priming has become an emergent strategy to alleviate abiotic stress and improve plant growth. During the current study, turnip seed priming with sodium selenite (Na2SeO3) was investigated for its ability to mitigate salt stress. Turnip (Brassica rapa L. var. Purple Top White Globe) seeds primed with 75, 100, and 125 μML−1 of Se were subjected to 200 mM salt stress under field conditions. Findings of the current field research demonstrated that salt toxicity declined seed germination, chlorophyll content, and gas exchange characteristics of B. rapa seedling. Whereas, Se-primed seeds showed higher germination rate and plant growth which may be attributed to the decreased level of hydrogen peroxide (H2O2) and malondialdehyde (MDA) decreased synthesis of proline (36%) and besides increased total chlorophyll (46%) in applied turnip plants. Higher expression levels of genes encoding antioxidative activities (CAT, POD, SO,D and APX) mitigated oxidative stress induced by the salt toxicity. Additionally, Se treatment decreased Na+ content and enhanced K+ content resulting in elevated K+/Na+ ratio in the treated plants. The in-silico assessment revealed the interactive superiority of Se with antioxidant enzymes including CAT, POD, SOD, and APX as compared to sodium chloride (NaCl). Computational study of enzymes-Se and enzymes-NaCl molecules also revealed the stress ameliorative potential of Se through the presence of more Ramachandran-favored regions (94%) and higher docking affinities of Se (-6.3). The in-silico studies through molecular docking of Na2SeO3, NaCl, and ROS synthesizing enzymes (receptors) including cytochrome P450 (CYP), lipoxygenase (LOX), and xanthine oxidase (XO), also confirmed the salt stress ameliorative potential of Se in B. rapa. The increased Ca, P, Mg, and Zn nutrients uptake nutrients uptake in 100 μML−1 Se primed seedlings helped to adjust the stomatal conductivity (35%) intercellular CO2 concentration (32%), and photosynthetic activity (41%) resulting in enhancement of the yield attributes. More number of seeds per plant (6%), increased turnip weight (115 gm) root length (17.24 cm), root diameter (12 cm) as well as turnip yield increased by (9%tons ha−1) were recorded for 100 μML−1 Se treatment under salinity stress. Findings of the current research judiciously advocate the potential of Se seed priming for salt stress alleviation and growth improvement in B. rapa.

Multidrug resistance phenotype and its relation to stem cell characteristics in chronic myeloid leukemia

The present work aimed to evaluate the expression profile of genes related to stem cells (SC) characteristics during the acquisition of the multidrug resistance (MDR) phenotype in the chronic myeloid leukemia (CML). For this, the K562 (non MDR) and FEPS (MDR) cell lines were used. K562 cells had resistance induced by exposure to daunorubicin (DNR), and induction was confirmed by flow cytometry with an increase in ABCB1 expression in K562 cells treated at the highest concentration. Real-time PCR gene expression analysis showed a direct relationship in the expression of OCT4 and ABCB1 genes, with an increase in ABCB1 expression after exposure to DNR, followed by an increase in OCT4 gene expression. This direct relationship was confirmed in the MDR FEPS cells that had the ABCB1 gene silenced. For the ALOX5 gene, we observed an inverse relationship with ABCB1, with a decrease in the expression of ALOX5 in the DNR-transformed K562 cells, and an increase in the expression of this gene when ABCB1 was silenced in the FEPS cells. Thus, during the acquisition of the MDR phenotype by the K562 cells, it was possible to observe that there is an increase in the expression of ABCB1, accompanied by the expression of OCT4, while the expression of ALOX5 is decreased.

12/15-lipoxygenase inhibition attenuates neuroinflammation by suppressing inflammasomes.

Lipoxygenases (LOXs) have essential roles in stroke, atherosclerosis, diabetes, and hypertension. 12/15-LOX inhibition was shown to reduce infarct size and brain edema in the acute phase of experimental stroke. However, the significance of 12/15-LOX on neuroinflammation, which has an essential role in the pathophysiology of stroke, has not been clarified yet. In this study, ischemia/recanalization (I/R) was performed by occluding the proximal middle cerebral artery (pMCAo) in mice. Either the 12/15-LOX inhibitor (ML351, 50 mg/kg) or its solvent (DMSO) was injected i.p. at recanalization after 1 h of occlusion. Mice were sacrificed at 6, 24, and 72-h after ischemia induction. Infarct volumes were calculated on Nissl-stained sections. Neurological deficit scoring was used for functional analysis. Lipid peroxidation was determined by the MDA assay, and the inflammatory cytokines IL-6, TNF-alpha, IL-1beta, IL-10, and TGF-beta were quantified by ELISA. The inflammasome proteins NLRP1 and NLRP3, 12/15-LOX, and caspase-1 were detected with immunofluorescence staining. Infarct volumes, neurological deficit scores, and lipid peroxidation were significantly attenuated in ML351-treated groups at 6, 24, and 72-h. ELISA results revealed that the pro-inflammatory cytokines IL-1beta, IL-6, and TNF-alpha were significantly decreased at 6-h and/or 24-h of I/R, while the anti-inflammatory cytokines IL-10 and TNF-alpha were increased at 24-h or 72-h of ML351 treatment. NLRP1 and NLRP3 immunosignaling were enhanced at three time points after I/R, which were significantly diminished by the ML351 application. Interestingly, NLRP3 immunoreactivity was more pronounced than NLRP1. Hence, we proceeded to study the co-localization of NLRP3 immunoreactivity with 12/15-LOX and caspase-1, which indicated that NLRP3 was co-localized with 12/15-LOX and caspase-1 signaling. Additionally, NLRP3 was found in neurons at all time points but in non-neuronal cells 72 h after I/R. These results suggest that 12/15-LOX inhibition suppresses ischemia-induced inflammation in the acute and subacute phases of stroke via suppressing inflammasome activation. Understanding the mechanisms underlying lipid peroxidation and its associated pathways, like inflammasome activation, may have broader implications for the treatment of stroke and other neurological diseases characterized by neuroinflammation.

An Overview of Arachidonic Acid Metabolic Pathway and Recent Updates on a Few Heterocyclic Derivatives showing COX-2 Inhibition

Inflammation crucial part of the immune response associated with a broad range of immunological diseases. The arachidonic acid (AA) pathway, which is an essential inflammatory mediator present at the internal surface of the cellular matrix, is hydrolyzed by phospholipase A2, which leads to the development of metabolites such as cytochrome P450 (CYP), lipoxygenases (LOXs), cyclooxygenases (Coxs) and enzymes which further develops into bioactive mediators such as prostanoids, leukotrienes (LTs) and more. Cyclooxygenases produce prostaglandins, available as 2 isomorphs, COX-1(constitutive) & COX-2(inducible), targeted by NSAIDs used to treat inflammation. Yet, they have a number of negative effects that lead to market withdrawal. Research has been done to look at novel COX-2 inhibitors and safety precautions. By structural alteration at COX-2 strong receiving site, structural along with functional research on a number of selective COX-2 blockers results in the creation of novel structures that are more potent and selective against inflammation while having a very low risk of side effects. This is made possible by computer-assisted medication design. This review gives an explanation regarding the biological functionalization of several COX-2 derivatives obtained by the help of in vitro, in vivo & molecular docking for better understanding of the structures and bonding accountable for an action

Variations of quality and volatile components of morels (Morchella sextelata) during storage

The postharvest senescence of morels was observed to be easily affected by temperature fluctuations. The objective of this study was to examine the influence of various storage temperatures on the postharvest senescence of morels. The study evaluated the variations of water content, respiration, nutrients substances, cell membrane permeability, and volatile compounds in morels stored at 20 °C and 4 °C. Results showed that low-temperature storage suppressed the loss of water and firmness, delayed the time of respiration and ethylene peak, and reduced the loss of nutrients and cell membrane permeability. Furthermore, the content of volatile compounds increased and then decreased during storage. The characteristic aroma substances of 1-octen-3-ol were identified using odor activity values and OPLS-DA analysis. The study observed a decrease in the content and changes of aroma compounds during low-temperature storage. This decrease may be attributed to the decreased activities of lipoxygenase (LOX) and alcohol dehydrogenase (ADH).

Transcriptome analysis reveals the mechanism of polyethylene atmosphere packaging delaying browning of postharvest Pleurotus eryngii

To elucidate the mechanism of low-density polyethylene(LDPE) atmosphere packaging on delaying browning of Pleurotus eryngii under a postharvest low-temperature storage, this study focused on exploring the effects of two thicknesses (0.02 and 0.05 mm) LDPE packaging on some antioxidant enzymes, and stress markers in P. eryngii. The results showed that LDPE atmosphere packaging maintained the phenolic content and higher superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) levels, reduced malondialdehyde (MDA) content, electrolyte leakage rate and polyphenol oxidase (PPO) levels in the mushroom. Also, transcriptome analyses showed that LDPE atmosphere packaging regulated the expression of enzymes PPO, POD, CAT and APX-related genes, inhibited the expression of lipoxygenases (LOX) and phospholipase D (PLD)-related genes and regulated the l-glutathione (GSH) antioxidant system. Overall, LDPE atmosphere packaging delayed the reduction of unsaturated fatty acids and energy loss by maintaining the integrity of cell membranes and regulating important genes involved in membrane lipid metabolism, energy metabolism, and respiratory metabolism of P. eryngii. In addition, it activated the expression of genes related to GSH synthesis and metabolism, thus enhancing the antioxidant capacity of mushroom body, reducing the accumulation of ROS and delaying browning.

Alkaloids from the roots of Sophora flavescens and their anti-tumor activity

Sophora flavescens belongs to Sophora genus of Leguminosae. Its roots are used as a traditional Chinese medicine. In our study on Sophora flavescens roots, 3 new and 19 known alkaloids have been found, including 8 aloperine-type and 14 matrine-type alkaloids. The planar configurations of these compounds were determined by the spectral data, and the absolute configurations of new compounds 1, 2 and 4 were determined by pyridine solvent effect, ECD and snatzke methods, respectively. All compounds were tested for their inhibitory activity on MCF-7 cell growth, and compound 12 exhibited certain inhibitory effects on the growth of MCF-7 cells after 24 h of treatment at a concentration of 20 μM, with inhibition rates of 31.28%. Through target screening and molecular docking, human Rho GTPase activating protein 5 variant and human arachidonate 12-lipoxygenase (12S-type) might be important targets for compound 12 to exert anti-tumor activity.

Postharvest Quality Exploration of “Crystal” Grapes in Karst Mountainous Area: Regulatory Effect of High Concentration 1-MCP Fumigation

The comprehensive exploration and thorough understanding of the physicochemical characteristics of “Crystal” grapes in the Karst area of Southwest China can not only produce edible table grapes, but also offer significant theoretical backing for the management of rocky desertification in the Karst area and consequently generate enhanced social and ecological benefits. This study explored the regulatory effect of 1-MCP fumigation on the postharvest storage quality of "Crystal” grapes, aiming to provide some technical support for the development of the grape industry in the Karst mountainous areas. The results indicate that compared with the control group, both the 10.0 and 50.0 μL/L 1-MCP treatment groups effectively inhibited the increase in decay rate, browning rate, shedding rate, and color change of the grapes, significantly inhibited the enhancement of polyphenol oxidase (PPO), peroxidase (POD), and lipoxygenases (LOX) browning-related enzyme activities, improved the superoxide dismutase (SOD) activity of the fruits, hindered the decrease of ascorbic acid (AsA) and polyphenols, delayed the accumulation of malondialdehyde (MDA) content, and significantly postponed the peak period of polygalacturonase (PG) activity in the fruits and the degradation of protopectin to soluble pectin, thereby maintaining desirable texture characteristics. The utilization of 1-MCP for fruit fumigation yielded a heightened overall fragrance, thereby facilitating the emission of terpenes, alcohols, aldehydes, ketone aromatic compounds, and methyl aromatic substances within the fruit. Overall, both the M10 and M50 treatments are equally effective in preserving the storage quality of “Crystal” grapes. Under the condition of ensuring the excellent edible quality of crystal grapes, M2 can extend the shelf life of crystal grapes by about 5 days, and M10 and M50 can extend the storage period of crystal grapes by 10~15 days. Considering the cost, it is recommended that the industry employs a concentration of 10.0 μL/L of 1-MCP for “Crystal” grapes. Simultaneously, this study also provides theoretical support for the ecologically high-quality development of cultivated land in the Karst mountainous area of Guizhou and tree selection.

CRISPR/Cas9-mediated lipoxygenase gene-editing in yellow pea leads to major changes in fatty acid and flavor profiles.

Although pulses are nutritious foods containing high amounts of protein, fiber and phytochemicals, their consumption and use in the food industry have been limited due to the formation of unappealing flavors/aromas described as beany, green, and grassy. Lipoxygenase (LOX) enzymes are prevalent among pulse seeds, and their activity can lead to the formation of specific volatile organic compounds (VOCs) from certain polyunsaturated fatty acids (PUFAs). As a widespread issue in legumes, including soybean, these VOCs have been linked to certain unappealing taste perception of foods containing processed pulse seeds. To address this problem in pea and as proof of principle to promote the wider use of pulses, a Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) construct was designed to create null alleles (knockouts) of PsLOX2 which had been implicated in the generation of VOCs in peas. Successful CRISPR/Cas9-mediated LOX gene editing of stable transgenic pea lines (TGP) was confirmed by DNA sequencing of the wild type (WT) and TGP pslox2 mutant lines. These lines were also assessed for LOX activity, PUFA levels, and VOCs. Compared to WT peas, the TGP lines showed a significant reduction (p < 0.05) in LOX activity and in the concentration of key VOCs, including hexanal, 2-hexenal, heptanal, (E)-2-heptenal, (E,E)-2,4-heptadienal, 1-octen-3-ol, octanal, (E)-2-octenal (E,E)-2,4-nonadienal and furan-2-pentyl. The content of two essential PUFAs, linoleic and α-linolenic acids, the known substrates of LOX in plants, was higher in TGP flours, indicating the efficacy of the CRISPR-mediated gene editing in minimizing their oxidation and the further modification of PUFAs and their products. The collection of VOCs from the headspace of ground pea seeds, using a portable eNose also distinguished the TGP and WT lines. Multiple regression analysis showed that LOX activity correlated with the two VOCs, heptanal and (E,E)-2,4-heptadienal in pea flours. Partial Least Squares Regression (PLS-R) plot for selected PUFAs, VOCs, and sensor responses in WT and TGP lines showed distinct clusters for WT and TGP lines. Together this data demonstrates the utility of CRISPR mediated mutagenesis of PsLOX2 to quickly improve aroma and fatty acid (FA) profiles of pea seeds of an elite Canadian variety.

A comprehensive investigation on the interaction between jaceosidin, baicalein and lipoxygenase: Multi-spectroscopic analysis and computational study

Lipoxygenase (LOX) has the harmful effect of accelerating lipid oxidation, and polyphenols have the inhibitory effect on lipoxygenase. However, there were rare researches investigated on the interactions between polyphenols and LOX. In this study, the binding mechanisms between polyphenols (Jaceosidin-JSD and baicalein-BCL) and LOX were investigated by multi-spectroscopic analysis and computational study. Both JSD and BCL binding to LOX resulted in static fluorescence quenching, and the complexes of JSD-LOX and BCL-LOX were built at a molar ratio of 1:1, respectively. The binding constants of LOX-JSD (72.18 × 105 L/mol at 298 K) and LOX-BCL (12.43 × 105 L/mol at 298 K) indicated that LOX had stronger binding affinity to JSD compared to BCL. Compared with BCL-LOX, the JSD-LOX system formed more hydrogen bonds which ensured a stronger bond between JSD and LOX. The studies in molecular dynamics also demonstrated that the JSD-LOX complex is more stable, and the addition of JSD is more conducive to the complex formation. The current study provides some new insights for the study on the inhibition of lipid oxidation and affords a new strategy for the discovery of novel food preservatives.

Comparative Analysis of Bio- and Chemo-Catalysts for the Synthesis of Flavour Compound Hexanal from Linoleic Acid

Hexanal, hexenal, nonenal and their corresponding alcohols are used as green notes in the fragrance and flavour industry. The production of bio-based hexanal starts from linoleic acid, which can be obtained from sunflower or safflower oil. The biocatalytic process utilizes C13-specific lipoxygenase (LOX) for hydroperoxidation and consecutive splitting with hydroperoxide lyase (HPL). In this study, we investigated the chemical splitting of the LOX product 13-HPODE in comparison to HPL catalysis. In addition, 13-HPODE was synthesized using enriched linoleic acid from safflower oil. Varying amounts of soybean flour suspension as a source of LOX yielded up to 60% HPODE with a regioselectivity of 92% towards 13-HPODE. Using low-toxicity Lewis acids like AlCl3 and ZrCl4, cleavage of the produced 13-HPODE was possible. A maximum hexanal yield of 22.9% was reached with AlCl3 under mild reaction conditions, though product degradation was an interfering process. Comparative trials with N-terminal truncated HPL from papaya revealed hexanal recovery within a comparable range. Additionally, we successfully demonstrated the viability of Hock rearrangement of 13-HPODE through heterogeneous catalysts. Notably, Beta zeolite and Montmorillonite K10 exhibited a turnover frequency (TOF) on par with common heterogeneous catalysts employed in industrial processes.

The apple lipoxygenase MdLOX3 positively regulates zinc tolerance

Various abiotic stresses, especially heavy metals near factories around the world, limit plant growth and productivity worldwide. Zinc is a light gray transition metal, and excessive zinc will inactivate enzymes in the soil, weaken the biological function of microorganisms, and enter the food chain through enrichment, thus affecting human health. Lipoxygenase (LOX) can catalyze the production of fatty acid derivatives from phenolic triglycerides in plants and is an important pathway of fatty acid oxidation in plants, which usually begins under unfavorable conditions, especially under biotic and abiotic stresses. Lipoxygenase can be divided into 9-LOX and 13-LOX. MdLOX3 is a homolog of AtLOX3 and has been identified in apples (housefly apples). MdLOX3 has a typical conserved lipoxygenase domain, and promoter analysis shows that it contains multiple stress response elements. In addition, different abiotic stresses and hormonal treatments induced the MdLOX3 response. In order to explore the inherent anti-heavy metal mechanism of MdLOX3, this study verified the properties of MdLOX3 based on genetic analysis and overexpression experiments, including plant taproots length, plant fresh weight, chlorophyll, anthocyanins, MDA, relative electrical conductivity, hydrogen peroxide and superoxide anion, NBT\\DAB staining, etc. In the experiment, overexpression of MdLOX3 in apple callus and Arabidopsis effectively enhanced the tolerance to zinc stress by improving the ability to clear ROS. Meanwhile, tomato materials with overexpression of ectopia grew better under excessive zinc ion stress. These results indicated that MdLOX3 had a good tolerance to heavy metal zinc. Homologous mutants are more sensitive to zinc, which proves that MdLOX3 plays an important positive role in zinc stressed apples, which broadens the range of action of LOX3 in different plants.

Effect of solvent viscosity on the activation barrier of hydrogen tunneling in the lipoxygenase reaction

Hydrogen tunneling in enzyme reactions has played an important role in linking protein thermal motions to the chemical steps of catalysis. Lipoxygenases (LOXs) have served as model systems for such reactions, showcasing deep hydrogen tunneling mechanisms associated with enzymatic C–H bond cleavage from polyunsaturated fatty acids. Here, we examined the effect of solvent viscosity on the protein thermal motions associated with LOX catalysis using trehalose and glucose as viscogens. Kinetic analysis of the reaction of the paradigm plant orthologue, soybean lipoxygenase (SLO), with linoleic acid revealed no effect on the first-order rate constants, kcat, or activation energy, Ea. Further studies of SLO active site mutants displaying varying Eas, which have been used to probe catalytically relevant motions, likewise provided no evidence for viscogen-dependent motions. Kinetic analyses were extended to a representative fungal LOX from M. oryzae, MoLOX, and a human LOX, 15-LOX-2. While MoLOX behaved similarly to SLO, we show that viscogens inhibit 15-LOX-2 activity. The latter implicates viscogen sensitive, conformational motions in animal LOX reactions. The data provide insight into the role of water hydration layers in facilitating hydrogen (quantum) tunneling in LOX.

Influence of High-Temperature and Intense Light on the Enzymatic Antioxidant System in Ginger (Zingiber officinale Roscoe) Plantlets.

Environmental stressors such as high temperature and intense light have been shown to have negative effects on plant growth and productivity. To survive in such conditions, plants activate several stress response mechanisms. The synergistic effect of high-temperature and intense light stress has a significant impact on ginger, leading to reduced ginger production. Nevertheless, how ginger responds to this type of stress is not yet fully understood. In this study, we examined the phenotypic changes, malonaldehyde (MDA) content, and the response of four vital enzymes (superoxide dismutase (SOD), catalase (CAT), lipoxygenase (LOX), and nitrate reductase (NR)) in ginger plants subjected to high-temperature and intense light stress. The findings of this study indicate that ginger is vulnerable to high temperature and intense light stress. This is evident from the noticeable curling, yellowing, and wilting of ginger leaves, as well as a decrease in chlorophyll index and an increase in MDA content. Our investigation confirms that ginger plants activate multiple stress response pathways, including the SOD and CAT antioxidant defenses, and adjust their response over time by switching to different pathways. Additionally, we observe that the expression levels of genes involved in different stress response pathways, such as SOD, CAT, LOX, and NR, are differently regulated under stress conditions. These findings offer avenues to explore the stress mechanisms of ginger in response to high temperature and intense light. They also provide interesting information for the choice of genetic material to use in breeding programs for obtaining ginger genotypes capable of withstanding high temperatures and intense light stress.

15-lipoxygenase and cyclooxygenase expression profile and their related modulators in COVID-19 infection

BackgroundThe role of the lipoxygenase (LOX) and cyclooxygenase (COX) enzymes in maintaining cellular homeostasis and regulating immune responses promoted us in this study to analyze the pattern of changes in 15-lipoxygenase and cyclooxygenase isoforms and their related cytokines in SARS-CoV-2 infection. Methods15-LOX-1, 15-LOX-2, COX-1 and COX-2 gene expression levels were determined using qRT-PCR in nasopharynx specimens from patients with severe [N = 40] and non-severe [N = 40] confirmed SARS-CoV-2 infections and healthy controls. Circulating levels of lL-6, lL-10, PGE2, and IFN-γ were measured in patients and healthy controls using ELISA assay. The associations between the measured variables and the patient's clinic-pathological characteristics were assessed for all groups. ResultsThe expression level of 15-LOX-1 was elevated significantly in male patients with severe infection; although female patients showed a different expression profile. 15-LOX-2 expression level was considerably increased in male patients with severe infection; while changes in its expression remained inconclusive in female patients. The relationship between 15-LOX expression and the male gender was prominent. Both COX isoforms expression showed elevation in male and female patients that were correlated with disease severity. The simultaneous increase in lL-6, PGE2 and IFN-γ levels also decrease in lL-10 in patients with severe infection indicating the possible regulatory network related to the COX and 15-LOX enzymes in the output of the SARS-CoV-2 infection. ConclusionThe results of this study determined the pattern of possible changes in key enzymes of prostaglandin and eicosanoids synthesis pathway and their mediators, which can be helpful in mapping the SARS-CoV-2 pathogenicity and pharmaceutical approaches.