LOX Activity Research Articles

Catalytic properties of lipoxygenase extracted from nine different Italian olive varieties (Olea europaea L.)

SummaryLipoxygenases (linoleate oxygen oxidoreductase, LOX, EC 1.13.11.12) are a class of dioxygenases found abundantly in the plant kingdom, which catalyse the oxygenation reaction of polyunsaturated fatty acids (PUFA). Considering the capacity of LOX to define the distinctive and refined “green” fruity aroma of virgin olive oil (VOO), the biochemical study was conducted to characterise lipoxygenase in pulp and stone of nine Italian varieties of Olea europaea [Canino, Carboncella, Frantoio, Itrana, Leccino, Maurino, Moraiolo, Rosciola and Sirole]. The crude extracts were analysed to determine the kinetic parameters (Vmax, KM and Vmax/KM) and their optimum pH and temperature. The measurement of the catalytic activity of the LOX extracted from pulp and stones revealed the highly efficient catalytic activity of all the pulp samples from most of the analysed cultivars. Moreover, the kinetic analyses conducted on all olive samples revealed that the Frantoio pulp provided the best performance in terms of LOX activity. All crude extracts showed the highest oxidase activity at pH 6, while the values relating to the optimal temperature were obtained at 50 °C. The results provide valuable insight into optimising the VOO extraction process, particularly the kinetic parameters that could be useful tools to modulate the malaxation process.

Design, Synthesis, Biological Evaluation, and Molecular Docking Study of 4,6-Dimethyl-5-aryl/alkyl-2-[2-hydroxy-3-(4-substituted-1-piperazinyl)propyl]pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-diones as Anti-Inflammatory Agents with Dual Inhibition of COX and LOX.

In the present study, we characterize the biological activity of a newly designed and synthesized series of 15 compounds 2-[2-hydroxy-3-(4-substituted-1-piperazinyl)propyl] derivatives of pyrrolo[3,4-c]pyrrole 3a-3o. The compounds were obtained with good yields of pyrrolo[3,4-c]pyrrole scaffold 2a-2c with secondary amines in C2H5OH. The chemical structures of the compounds were characterized by 1H-NMR, 13C-NMR, FT-IR, and MS. All the new compounds were investigated for their potencies to inhibit the activity of three enzymes, i.e., COX-1, COX-2, and LOX, by a colorimetric inhibitor screening assay. In order to analyze the structural basis of interactions between the ligands and cyclooxygenase/lipooxygenase, experimental data were supported by the results of molecular docking simulations. The data indicate that all of the tested compounds influence the activity of COX-1, COX-2, and LOX.

Chemical profile, in vitro pharmacological activity and Satureja cuneifolia Ten. evaluation of essential oil based on distillation time

ABSTRACT The medicinal plant Satureja cuneifolia Ten. was widely utilized as spice, tea and traditional medicine. The objective of the current study was to examine the chemical composition and in vitro biological activities (LOX, MMP-1, and MMP-12 enzyme inhibition activity and cytotoxicity on A549 cell line) of Satureja cuneifolia extracts and essential oils. The essential oils of the flowering aerial parts were hydro-distilled at four different distillation times (5, 30, 60, and 180 min) using the Clevenger apparatus. The total essential oil and four fragments were compared in terms of the major component, yield, and distillation time. Volatile compounds of the infusion were extracted by using HS-SPME. Ethanolic extract had the strongest inhibition activity on the LOX enzyme (84.50%), while the essential oils exhibited more cytotoxic activity on the A549 cell line than the extracts. The oils and the infusion were analyzed using GC-MS and the primary chemicals identified by LC-MS/MS.

Exposure to oxLDL impairs TGF-β activity in human tendon cells

BackgroundPrevious studies have shown that patients with hypercholesterolemia experience elevated levels of oxidized LDL (oxLDL), a molecule which triggers inflammation and collagenase activity. In this study we discovered novel mechanistic effects of oxLDL on tendon cells and the mediators regulating matrix remodeling by analyzing the expression and activity of related proteins and enzymes. These effects may contribute to tendon damage in patients with high cholesterol.MethodsIsolated human tendon cells (male and female donors age 28 ± 1.4 age 37 ± 5.7, respectively) were incubated in the presence or absence of oxLDL. The influence of oxLDL on the expression level of key mRNA and proteins was examined using real time quantitative PCR, ELISA and Western blots. The activities of enzymes relevant to collagen synthesis and breakdown (lysyl oxidase and matrix metalloproteinases) were quantified using fluorometry. Finally, the isolated human tendon cells in a 3D construct were exposed to combinations of oxLDL and TGF-β to examine their interacting effects on collagen matrix remodeling.ResultsThe one-way ANOVA of gene expression indicates that key mRNAs including TGFB, COL1A1, DCN, and LOX were significantly reduced in human tendon cells by oxLDL while MMPs were increased. The oxLDL reduced the activity of LOX at 50 µg/ml, whereas conversely MMP activities were induced at 25 µg/ml (P ≤ 0.01). COL1A1 synthesis and TGF-β secretion were also inhibited (P ≤ 0.05). Adding recombinant TGF-β reversed the effects of oxLDL on the expression of collagens and LOX. OxLDL also impaired collagen matrix remodeling (P ≤ 0.01), and adding TGF-β restored the native phenotype.ConclusionExposure to oxLDL in patients with hypercholesterolemia may adversely affect the mechanical and structural properties of tendon tissue through a direct action of oxLDL on tendon cells, including impairment of TGF-β expression. This impairment leads to disturbed matrix remodeling and synthesis, thereby potentially leading to increased risk of acute or chronic tendon injury. Our discovery may provide an opportunity for developing effective treatments for tendon injury in hypercholesterolemia patients by targeting the TGF-β pathway.

Refractance window drying of walnut kernel (Juglans regia L.)

The present study aimed to determine the effect of refractance window (RW) drying and compare it with sun drying for various physicochemical properties of walnut kernels. Physical properties such as moisture content, texture, color analysis, and water activity were analyzed and results were found to be better than sun drying. The ΔE value of kernels was found lowest (4.36) at 70 °C and texture profile results were found better than those of walnut kernels obtained by sun drying. The total phenolic content, and the antioxidant activity of the RW-dried product were found significantly higher than the sun-dried sample. The TPC value of the RW dried sample obtained at 90 °C was found maximum to be 2710 ± 2.75 mg GAE/100 g. The IC50 value of RW dried walnut kernel was found lowest (4.12 ± 0.45 µg/mL) at 50 °C. The LOX activity of all samples was significantly lower in the case of RW drying. The lowest value was obtained (0.065 ± 0.015 µkat) at 50 °C. The CHNO(S) test depicted lower lipid oxidation in the case of RW-dried samples.

DNP and ATP regulate the breakdown occurrence in the pulp of Phomopsis longanae Chi-infected longan fruit through modulating the metabolism of membrane lipid

This study aimed to illustrate how DNP and ATP affected the pulp breakdown occurrence in P. longanae-infected longan and their relationship with the membrane lipid metabolism. Compared with P. longanae-inoculated samples, the pulp of DNP-treated P. longanae-infected longan exhibited higher cellular membrane permeability, breakdown index, activities of PI-PLC, PLD, PC-PLC, LOX, and lipase, and values of SFAs, PA, and DAG, while lower levels of PI, PC, USFAs, IUFA and U/S. However, the opposite findings were observed in ATP-treated P. longanae-infected longan. The data manifested that DNP-increased the pulp breakdown occurrence in P. longanae-inoculated samples was due to the elevated MLDEs activities that reduced the contents of phospholipids (PI, PC) and USFAs, disrupting the cell membrane structures. Nevertheless, ATP decreased the pulp breakdown occurrence in P. longanae-inoculated samples, which was ascribed to the reduced MLDEs activities that raised phospholipids (PI, PC) and USFAs contents, thus maintaining the cell membrane structures.

Discovery of 5-Methylthiazole-Thiazolidinone Conjugates as Potential Anti-Inflammatory Agents: Molecular Target Identification and In Silico Studies

A series of previously synthesized 5-benzyliden-2-(5-methylthiazole-2-ylimino)thiazoli- din-4-one were evaluated for their anti-inflammatory activity on the basis of PASS predictive outcomes. The predictive compounds were found to demonstrate moderate to good anti-inflammatory activity, and some of them displayed better activity than indomethacin used as the reference drug. Structure-activity relationships revealed that the activity of compounds depends not only on the nature of the substituent but also on its position in the benzene ring. The most active compounds were selected to investigate their possible mechanism of action. COX and LOX activity were determined and found that the title compounds were active only to COX-1 enzymes with an inhibitory effect superior to the reference drug naproxen. As for LOX inhibitory activity, the derivatives failed to show remarkable LOX inhibition. Therefore, COX-1 has been identified as the main molecular target for the anti-inflammatory activity of our compounds. The docking study against COX-1 active site revealed that the residue Arg 120 was found to be responsible for activity. In summary, the 5-thiazol-based thiazolidinone derivatives have been identified as a novel class of selective COX-1 inhibitors.

Extension of postharvest life by application of edible coatings on tomatoes var. 234 with silencing of the TomLoxb gene

ABSTRACT Fruit mutants with the silenced TomloxB gene (tomato lipoxygenase B) have proven to be an alternative in extending postharvest life; however, their interaction with other classical technologies, such as the use of edible coatings, has been scarcely explored. The synergy between the two treatments can improve aspects of fruit quality during its postharvest life or even increase this period. Therefore, the objective of this study was to evaluate the effect of coatings (candelilla wax (CW) and Semperfresh® (S)) on the postharvest life and lipoxygenase activity of genetically modified (GM) tomatoes. Wild Type (WT) and GM tomatoes with the antisense TomLoxB gene insertion were used. LOX activity values on day 18 were 721 U/mg protein, in fruits coated with CW, below the WT fruit (859 U/mg protein) and other GM fruits with other coatings (916 to 996 U/mg protein). CW was the coating that exhibited the best results in preserving the postharvest life of the GM tomato for up to 30 days, compared to the other coatings (24 days). Genetic modification in tomatoes prolonged their postharvest life, which increased further with the use of coatings such as CW.

Abstract 15554: Smooth Muscle Cells Specific Gene Inactivation of Lysyl Oxidase Reduces Atherosclerosis Burden and Plaque Calcification in Hyperlipidemic Mice

Aim: Dissect the mechanisms by which LOX increases atherogenesis and plaque calcification in hyperlipidemic mice. Methods: LOX conditional knockout [LOX f/f Myh11-CreER T2 ApoE -/- ] and control littermate [LOX wt/wt Myh11-CreER T2 ApoE -/- ] mice were injected with tamoxifen before high fat diet (HFD) feeding for atherosclerosis and calcification assessment and molecular analyses. Results: scRNA sequence showed full Lox gene inactivation in 72.5% of the aortic SMCs without any significant Loxl compensatory regulation. Gene deletion in SMCs decreased global arterial LOX deposition by ~3-fold in relation to control mice. Surprisingly, the loss of vascular LOX neither promoted aneurysm nor affected the aorta's stiffness. However, it reduced atherosclerosis burden (WT: 23±1 vs. KO: 13±2 %, p ≤0.01) and calcium deposition (11.8±3 versus 5±0.4%, p≤ 0.05) within the plaque after 16 weeks of high fat diet (HFD). Using bulk RNA sequencing, we further demonstrated that Lox gene inactivation leads to a marked decrease in Frizzled Related Protein-3 (FRZB) gene expression (127-fold and p≤0.0001), a biphasic modulator of the proatherogenic Wnt signaling that facilitates the association of β-catenin with TCF4 in the nucleus. The compromised FRZB /β-catenin/TCF4 signaling axis reduced the downstream production of Bone Morphogenetic Protein 2 (BMP2), which is responsible for the osteogenic transition of SMCs. Further scRNAseq analysis of atherosclerotic aortas from conditional KO and control mice also showed a reduction of BMP2 in SMCs. Interestingly, genetic inactivation of LOX increased the number of contractile SMCs (KO: 40 vs. WT: 7 %), characterized by the high expression of ACTA2 and TAGLN, in the aorta of HFD fed mice when compared to the control group. BAPN, an irreversible inhibitor of LOX activity, was not able to reduce BMP2 expression and protein levels nor reduce calcium deposition in vitro, suggesting that the pro-calcification effect of LOX is not activity dependent. Conclusions: Vascular gene inactivation of Lox protects mice against atherosclerosis by reducing β-catenin/TCF4/BMP2 proatherogenic signaling.

EMILIN1 deficiency causes arterial tortuosity with osteopenia and connects impaired elastogenesis with defective collagen fibrillogenesis

EMILIN1 (elastin-microfibril-interface-located-protein-1) is a structural component of the elastic fiber network and localizes to the interface between the fibrillin microfibril scaffold and the elastin core. How EMILIN1 contributes to connective tissue integrity is not fully understood. Here, we report bi-allelic EMILIN1 loss-of-function variants causative for an entity combining cutis laxa, arterial tortuosity, aneurysm formation, and bone fragility, resembling autosomal-recessive cutis laxa type 1B, due to EFEMP2 (FBLN4) deficiency. In both humans and mice, absence of EMILIN1 impairs EFEMP2 extracellular matrix deposition and LOX activity resulting in impaired elastogenesis, reduced collagen crosslinking, and aberrant growth factor signaling. Collagen fiber ultrastructure and histopathology in EMILIN1- or EFEMP2-deficient skin and aorta corroborate these findings and murine Emilin1-/- femora show abnormal trabecular bone formation and strength. Altogether, EMILIN1 connects elastic fiber network with collagen fibril formation, relevant for both bone and vascular tissue homeostasis.

Analysis of the aroma volatile compounds in different stabilized rice bran during storage

Rice bran is rich in nutrients and bioactive components, which plays an important role in reducing dyslipidemia and regulating intestinal flora. However, due to the rice bran’s instability resulting from rancidity during storage, the development is limited. E-nose, GC–MS and E-tongue were used to monitor the flavor and bitterness of different stabilized rice bran during accelerated storage, and the change of physicochemical properties in rice bran was determined. The rice bran flavor significantly changed after five stabilization treatments. The bitterness increased during storage, but the growth was small (from 7.39 to 7.62). Besides, after stabilization treatments, lipase (LA) activities gradually decreased from 10.11 to 2.03 mg/g, and lipoxygenase (Lox) activities decreased from 3.71 to 1.38 U/g. These results comprehensively elucidate changes in volatile composition, bitterness and physicochemical properties of stabilized rice bran samples during storage and lay the foundation for improving its acceptability and edibility in the future.

Low voltage electrostatic field treatment of fresh-cut pineapples with slightly acidic electrolytic water: Influence on physicochemical changes and membrane stability

The synergistic impact of slightly acidic electrolyzed water (SAEW, pH 6.7; ACC 30 mg/L) and low voltage electrostatic field (LVEF, 150 V 1000 Hz) on the membrane stability and quality of fresh-cut pineapples during 12 d cold storage were investigated. The results show that LVEF+SAEW treatment decreased by 0.25–4.38% moisture loss compared with other groups, inhibited the decline in hardness and maintained good sensory quality. The oxidation and decomposition of ascorbic acid could be effectively suppressed, and the total phenol content was maintained at a high level by adjusting the phenol metabolic enzyme (such as PAL and PPO). The retardation of browning effectively suppressed the decrease of L* value. The LVEF+SAEW treatment weakened the breathing intensity cause by cutting injury, increased ROS clearance enzyme activity (such as SOD, CAT), and reduced the H2O2 content. The increase rate of ROS and LOX activity was inhibited, the final product MDA content of membrane lipid oxidation was decreased, which could maintain the stability of the membrane. SAEW pre-washing combined with LVEF storage could be used commercially as cost-effective method for extending the shelf-life of fresh-cut pineapples.

Engineering sigma factors and chaperones for enhanced heterologous lipoxygenase production in Escherichia coli

BackgroundLipoxygenase (EC. 1.13.11.12, LOX) can catalyze the addition of oxygen into polyunsaturated fatty acids to produce hydroperoxides, which are widely used in the food, chemical, and pharmaceutical industries. In recent years, the heterologous production of LOX by Escherichia coli has attracted extensive attention. However, overexpressed recombinant LOX in E. coli aggregates and forms insoluble inclusion bodies owing to protein misfolding.ResultsIn this study, a split green fluorescent protein-based screening method was developed to screen sigma (σ) factors and molecular chaperones for soluble LOX expression. Three mutant libraries of Skp, GroES, and RpoH was analyzed using the high-throughput screening method developed herein, and a series of mutants with significantly higher yield of soluble heterologous LOX were obtained. The soluble expression level of LOX in the isolated mutants increased by 4.2- to 5.3-fold. Further, the highest LOX activity (up to 6240 ± 269 U·g-DCW−1) was observed in E. coli REopt, with the regulatory factor mutants, RpoH and GroES. Based on RNA-Seq analysis of the selected strains, E. coli Eopt, E. coli Sopt, E. coli Ropt, and wild type, amino acid substitutions in σ factors and molecular chaperones regulated the expression level of genes related to gene replication, recombination, and repair. Furthermore, the regulatory factor mutants were identified to be beneficial to the soluble expression of two other heterologous proteins, amylase and bone morphological protein 12.ConclusionIn this study, a high-throughput screening method was developed for improved soluble LOX expression. The obtained positive mutants of the regulatory factor were analyzed and employed for the expression of other heterologous proteins, thus providing a potential solution for the inclusion-body protein.

Arbuscular Mycorrhizal Fungus “Rhizophagus irregularis” impacts on physiological and biochemical responses of ryegrass and chickpea plants under beryllium stress

Heavy metals such as beryllium (Be) have been identified as toxic for plants with a negative impact on plant growth. Therefore, there is an urgent need for environmentally friendly techniques to reduce Be toxicity on plant growth and productivity. To this end, arbuscular mycorrhizal fungi (AMF) are widely applied to induce plant growth and stress tolerance. However, how AMF-plant symbiosis can support plants under Be stress has not been studied. Accordingly, we investigated the physiological and biochemical responses of AMF inoculated ryegrass and chickpea plants to Be stress. The associated changes in Be uptake and accumulation, photosynthesis, oxidative stress, carbon and nitrogen metabolism were studied. Soil contamination with Be induced higher Be accumulation, particularly in ryegrass, which consequentially reduced plant growth and photosynthesis. However, photorespiration and oxidative damage (H2O2 accumulation, lipid oxidation, and LOX activity) were increased, mainly in ryegrass. In both plant species, AMF inoculation reduced Be accumulation and mitigated growth inhibition and oxidative damage, but to a more extent in ryegrass. This could be explained by improved photosynthesis as well as the upregulation of osmoprotectants i.e., sucrose and proline biosynthesis pathways. The increase in proline level was consistent with higher nitrogen (N) metabolism as reflected by N level and nitrate reductase. Species-specific responses were recorded and supported by principal component analysis. This study provided insight into the mechanism of AMF's impact on Be-stressed ryegrass and chickpea plants. Hence, the current research suggested that AMF inoculation could be used as a viable strategy to mitigate Be phytotoxicity in ryegrass and chickpea plants.

Diversified Effects of COVID-19 as a Consequence of the Differential Metabolism of Phospholipids and Lipid Peroxidation Evaluated in the Plasma of Survivors and Deceased Patients upon Admission to the Hospital.

As a result of SARS-CoV-2 infection, inflammation develops, which promotes oxidative stress, leading to modification of phospholipid metabolism. Therefore, the aim of this study is to compare the effects of COVID-19 on the levels of phospholipid and free polyunsaturated fatty acids (PUFAs) and their metabolites produced in response to reactions with reactive oxygen species (ROS) and enzymes (cyclooxygenases-(COXs) and lipoxygenase-(LOX)) in the plasma of patients who either recovered or passed away within a week of hospitalization. In the plasma of COVID-19 patients, especially of the survivors, the actions of ROS and phospholipase A2 (PLA2) cause a decrease in phospholipid fatty acids level and an increase in free fatty acids (especially arachidonic acid) despite increased COXs and LOX activity. This is accompanied by an increased level in lipid peroxidation products (malondialdehyde and 8-isoprostaglandin F2α) and lipid mediators generated by enzymes. There is also an increase in eicosanoids, both pro-inflammatory as follows: thromboxane B2 and prostaglandin E2, and anti-inflammatory as follows: 15-deoxy-Δ-12,14-prostaglandin J2 and 12-hydroxyeicosatetraenoic acid, as well as endocannabinoids (anandamide-(AEA) and 2-arachidonylglycerol-(2-AG)) observed in the plasma of patients who recovered. Moreover, the expression of tumor necrosis factor α and interleukins (IL-6 and IL-10) is increased in patients who recovered. However, in the group of patients who died, elevated levels of N-oleoylethanolamine and N-palmitoylethanolamine are found. Since lipid mediators may have different functions depending on the onset of pathophysiological processes, a stronger pro-inflammatory response in patients who have recovered may be the result of the defensive response to SARS-CoV-2 in survivors associated with specific changes in the phospholipid metabolism, which could also be considered a prognostic factor.

Evaluation of the effect of Castanea sativa extracts on lipoxygenase activity

Lipoxygenase LOX is a lipolysis enzyme that oxidises unsaturated fatty acids like arachidonic and linoleic acids to form unhealthy chemicals such as dienes, leukotrienes and malondialdehyde in advanced oxidation, which is harmful to cells. In this study, the polyphenols and saponins compounds were extracted from Castanea sativa using Soxhlet for 3 days. Colourimetric and HPLC techniques were used to identify polyphenols and saponins in the extracts respectively. The effects of these extracts were evaluated on LOX activity, which was purified from the liver of Iraqi Cows (AL-Sharabi Cows) as well as on E. coli and Pseudomonas bacteria resistance. According to the LOX purification procedures, the specific activity increased from 0.001 to 0.03 U/mg with a purification fold of 30 times and a yield percentage of 174. Gallic acid 7.72 mg, Rutin 29.25 mg, Quercetin 27.6 mg, kaempferol 34.42 mg, Apigenin 5.25 mg and Catechin 25.8 mg/100 gm of Castanea fruit was obtained. The inhibitory effect of polyphenol and saponin extracts on LOX activity was at 100 and 40 µg respectively. Line weaver-Burk plot was used to investigate the type of inhibition that was found non-competitive. However, these extracts were studied at concentrations of 500, 250 and 125 µg on bacteria resistance. Polyphenols had the best effect at 500 and 125 µg on E. coli and Pseudomonas bacteria respectively. Whereas, saponin had the best effect at 250 and 125 µg for E. coli and 125 µg for Pseudomonas.

Circadian Rhythm Regulates Reactive Oxygen Species Production and Inhibits Al-Induced Programmed Cell Death in Peanut.

Peanut is among the most important oil crops in the world. In the southern part of China, peanut is highly produced; however, the arable land is acidic. In acidic soils, aluminum (Al) inhibits plant growth and development by changing the properties of the cell wall and causing the disorder of the intracellular metabolic process. Circadian rhythm is an internal mechanism that occurs about every 24 h and enables plants to maintain internal biological processes with a daily cycle. To investigate the effect of photoperiod and Al stress on the Al-induced programmed cell death (PCD), two peanut varieties were treated with 100 μM AlCl3 under three photoperiodic conditions (8/16, SD; 12/12, ND; 16/8 h, LD). The results show that Al toxicity was higher in ZH2 than in 99-1507 and higher under LD than under SD. Root length decreased by 30, 37.5, and 50% in ZH2 and decreased by 26.08, 34.78, and 47.82% in 99-1507 under SD, ND, and LD, respectively, under Al stress. Photoperiod and Al induced cell death and ROS production. MDA content, PME activity, and LOX activity increased under SD, ND, and LD, respectively, under Al stress both in ZH2 and 99-1507. APX, SOD, CAT, and POD activities were higher under SD, ND, and LD, respectively. Al stress increased the level of AhLHY expression under SD and ND but decreased it under LD in both ZH2 and 99-1507. Contrastingly, AhSTS expression levels increased exponentially and were higher under SD, LD, and ND, respectively, under Al stress. Our results will be a useful platform to research PCD induced by Al and gain new insights into the genetic manipulation of the circadian clock for plant stress response.

Effects of Levofloxacin, Aztreonam, and Colistin on Enzyme Synthesis by P. aeruginosa Isolated from Cystic Fibrosis Patients

(1) Background: Cystic fibrosis (CF) is characterized by chronic pulmonary inflammation and persistent bacterial infections. P. aeruginosa is among the main opportunistic pathogens causing infections in CF. P. aeruginosa is able to form a biofilm, decreasing antibiotic permeability. LOX, a lipoxygenase enzyme, is a virulence factor produced by P. aeruginosa and promotes its persistence in lung tissues. The aim of this study is to evaluate if antibiotics currently used for aerosol therapy in CF are able to interfere with the production of lipoxygenase from open isolates of P. Aeruginosa from patients with CF. (2) Methods: Clinical isolates of P. aeruginosa from patients with CF were grown in Luria broth (LB). Minimum inhibitory concentration (MIC) was performed and interpreted for all isolated strains according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. We selected four antibiotics with different mechanisms of action: aztreonam, colistin, amikacin, and levofloxacin. We used human pulmonary epithelial NCI-H929 cells to evaluate LOX activity and its metabolites according to antibiotic action at increasing concentrations. (3) Results: there is a correlation between LOX secretion by clinical isolates of P. aeruginosa and biofilm production. Levofloxacin exhibits highly significant inhibitory activity compared to the control. Amikacin also exhibits significant inhibitory activity against LOX production. Aztreonam and colistin do not show inhibitory activity. These results are also confirmed for LOX metabolites. (4) Conclusions: among the evaluated antibiotics, levofloxacin and amikacin have an activity on LOX secretion.

Angiogenic ability of human endothelial cells was decreased following senescence induction with hydrogen peroxide: possible role of vegfr-2/akt-1 signaling pathway

BackgroundMany attempts are used to discover mechanisms driving impaired angiogenesis in age-related diseases. Angiogenesis is highly regulated by different signaling pathways. Here, we investigated the angiogenesis potential of human endothelial cells (ECs) upon exposure to hydrogen peroxide (H2O2), a cellular senescent factor.ResultsData showed that the wound healing rate of HUVECs decreased upon incubation with H2O2 (P < 0.05). LOX activity and NO production were decreased in H2O2 treated cells (P < 0.05). Expression of miR-126 and VEGFR-2 up-regulated, while expression of miR-373 and HSP-70 up = regulated in H2O2 -induced cells (P < 0.05). In addition, we found that protein levels of p-Akt-1, VCAM-1, MMP-9, and IL-6 decreased in treated cells (P < 0.05).ConclusionsOur data showed that H2O2 reduced the angiogenic response of HUVECs in vitro, which may be due to impairment of the VEGFR-2 signaling pathway.

The Dynamic Change in Fatty Acids during the Postharvest Process of Oolong Tea Production.

As important factors to oolong tea quality, the accumulation and dynamic change in aroma substances attracts great attention. The volatile composition of oolong tea is closely related to the precursor contents. Fatty acids (FAs) and their derivatives are basic components of oolong tea fragrance during the postharvest process. However, information about the precursors of FAs during the postharvest process of oolong tea production is rare. To investigate the transformation of fatty acids during the process of oolong tea production, gas chromatograph–flame ionization detection (GC-FID) was conducted to analyze the composition of FAs. The results show that the content of total polyunsaturated FAs initially increased and then decreased. Specifically, the contents of α-linolenic acid, linoleic acid and other representative substances decreased after the turn-over process of oolong tea production. The results of partial least squares discrimination analysis (PLS-DA) showed that five types of FAs were obviously impacted by the processing methods of oolong tea (VIP > 1.0). LOX (Lipoxygenase, EC 1.13.11.12) is considered one of the key rate-limiting enzymes of long-chain unsaturated FAs in the LOX-HPL (hydroperoxide lyase) pathway, and the mechanical wounding occurring during the postharvest process of oolong tea production greatly elevated the activity of LOX.