Selective Production of 9R-Hydroxy-10E,12Z,15Z-Octadecatrienoic Acid from α-Linolenic Acid in Perilla Seed Oil Hydrolyzate by a Lipoxygenase from Nostoc Sp. SAG 25.82

Efficient biotransformation of docosahexaenoic acid-rich oils into the lipid mediator resolvin D5 by cells expressing 15S-lipoxygenase using a bioreactor

Resolvin D5 (RvD5), 7S,17S-dihydroxy-4Z,8E,10Z,13Z,15E,19Z-docosahexaenoic acid (DHA) is a specialized pro-resolving mediator (SPM) generated in human macrophages. It is implicated in the resolution of inflammation and synthesized using an inefficient chemical process. Here, DHA-enriched oil hydrolysate was prepared from oils by lipase with resin treatment and solvent extraction. The reaction factors on the biotransformation of oil hydrolysate into RvD5 were optimized using Escherichia coli expressing arachidonate double-oxygenating 15S-lipoxygenase. After optimization, the cells converted 5.0 mM (1.64 g/L) DHA in oil hydrolysate into 4.0 mM (1.44 g/L) RvD5 in a bioreactor for 3.0 h, which was 15-fold higher than that in a flask before optimization, and RvD5 with a purity of > 97% was prepared from reaction solution by treatments of resins. This is the first trial for the production of C22-dihydroxy fatty acid using a bioreactor. This study will contribute to the large-scale production of SPMs from oils.

Computational Insights and In Silico Characterization of a Novel Mini-Lipoxygenase from Nostoc Sphaeroides and Its Application in the Quality Improvement of Steamed Bread

Lipoxygenase (EC1.13.11.12, LOX) has been potentially used in the food industry for food quality improvement. However, the low activity, poor thermal stability, narrow range of pH stability, as well as undesirable isoenzymes and off-flavors, have hampered the application of current commercial LOX. In this study, a putative mini-lipoxygenase gene from cyanobacteria, Nostoc sphaeroides (NsLOX), was cloned and expressed in E. coli BL21. NsLOX displayed only 26.62% structural identity with the reported LOX from Cyanothece sp., indicating it as a novel LOX. The purified NsLOX showed the maximum activity at pH 8.0 and 15 °C, with superior stability at a pH range from 6.0 to 13.0, retaining about 40% activity at 40 °C for 90 min. Notably, NsLOX exhibited the highest specific activity of 78,080 U/mg towards linoleic acid (LA), and the kinetic parameters-K_m, k_cat, and k_cat/K_m-attain values of 19.46 μM, 9199.75 s^-1, and 473.85 μM^-1 s^-1, respectively. Moreover, the activity of NsLOX was obviously activated by Ca²⁺, but it was completely inhibited by Zn²⁺ and Cu²⁺. Finally, NsLOX was supplied in steamed bread and contributed even better improved bread quality than the commercial LOX. These results suggest NsLOX as a promising substitute of current commercial LOX for application in the food industry.

Synthesis of Linoleic Acid 13-Hydroperoxides from Safflower Oil Utilizing Lipoxygenase in a Coupled Enzyme System with In-Situ Oxygen Generation

Linoleic acid hydroperoxides are versatile intermediates for the production of green note aroma compounds and bifunctional ω-oxo-acids. An enzyme cascade consisting of lipoxygenase, lipase and catalase was developed for one-pot synthesis of 13-hydroperoxyoctadecadienoic acid starting from safflower oil. Reaction conditions were optimized for hydroperoxidation using lipoxygenase 1 from Glycine max (LOX-1) in a solvent-free system. The addition of green surfactant Triton CG-110 improved the reaction more than two-fold and yields of >50% were obtained at linoleic acid concentrations up to 100 mM. To combine hydroperoxidation and oil hydrolysis, 12 lipases were screened for safflower oil hydrolysis under the reaction conditions optimized for LOX-1. Lipases from Candida rugosa and Pseudomonas fluorescens were able to hydrolyze safflower oil to >75% within 5 h at a pH of 8.0. In contrast to C. rugosa lipase, the enzyme from P. fluorescens did not exhibit a lag phase. Combination of P. fluorescens lipase and LOX-1 worked well upon LOX-1 dosage and a synergistic effect was observed leading to >80% of hydroperoxides. Catalase from Micrococcus lysodeikticus was used for in-situ oxygen production with continuous H2O2 dosage in the LOX-1/lipase reaction system. Foam generation was significantly reduced in the 3-enzyme cascade in comparison to the aerated reaction system. Safflower oil concentration was increased up to 300 mM linoleic acid equivalent and 13-hydroperoxides could be produced in a yield of 70 g/L and a regioselectivity of 90% within 7 h.

Search for Natural Compounds That Increase Apolipoprotein A-I Transcription in HepG2 Cells: Specific Attention for BRD4 Inhibitors

Although increasing apolipoprotein A‐I (apoA‐I) might lower the cardiovascular disease risk, knowledge on natural compounds that elevate apoA‐I transcription is limited. Therefore, the aim of this study was to discover natural compounds that increase apoA‐I transcription in HepG2 cells. Since BRD4 inhibition is known to elevate apoA‐I transcription, we focused on natural BRD4 inhibitors. For this, the literature was screened for compounds that might increase apoA‐I and or inhibit BRD4. This resulted in list A, (apoA‐I increasers with unknown BRD4 inhibitor capacity), list B (known BRD4 inhibitors that increase apoA‐I), and list C (BRD4 inhibitors with unknown effect on apoA‐I). These compounds were compared with the compounds in two natural compound databases. This resulted in (1) a common substructure (ethyl‐benzene) in 60% of selected BRD4‐inhibitors, and (2) four compounds that increased ApoA‐I: hesperetin, equilenin, 9(S)‐HOTrE, and cymarin. Whether these increases are regulated via BRD4 inhibition and the ethyl‐benzene structure inhibits BRD4 requires further study.

Microbial Synthesis of Linoleate 9 S-Lipoxygenase Derived Plant C18 Oxylipins from C18 Polyunsaturated Fatty Acids

Plant oxylipins, including hydroxy fatty acids, epoxy hydroxy fatty acids, and trihydroxy fatty acids, which are biosynthesized from C18 polyunsaturated fatty acids (PUFAs), are involved in pathogen-specific defense mechanisms against fungal infections. However, their quantitative biotransformation by plant enzymes has not been reported. A few bacteria produce C18 trihydroxy fatty acids, but the enzymes and pathways related to the biosynthesis of plant oxylipins in bacteria have not been reported. In this study, we first report the biotransformation of C18 PUFAs into plant C18 oxylipins by expressing linoleate 9 S-lipoxygenase with and without epoxide hydrolase from the proteobacterium Myxococcus xanthus in recombinant Escherichia coli. Among the nine types of plant oxylipins, 12,13-epoxy-14-hydroxy- cis, cis-9,15-octadecadienoic acid was identified as a new compound by NMR analysis, and 9,10,11-hydroxy- cis, cis-6,12-octadecadienoic acid and 12,13,14-trihydroxy- cis, cis-9,15-octadecadienoic were suggested as new compounds by LC-MS/MS analysis. This study shows that bioactive plant oxylipins can be produced by microbial enzymes.

Functional characterization of a novel arachidonic acid 12S-lipoxygenase in the halotolerant bacterium Myxococcus fulvus exhibiting complex social living patterns

Lipoxygenases are lipid peroxidizing enzymes, which frequently occur in higher plants and mammals. These enzymes are also expressed in lower multicellular organisms but here they are not widely distributed. In bacteria, lipoxygenases rarely occur and evaluation of the currently available bacterial genomes suggested that <0.5% of all sequenced bacterial species carry putative lipoxygenase genes. We recently rescreened the public bacterial genome databases for lipoxygenase-like sequences and identified two novel lipoxygenase isoforms (MF-LOX1 and MF-LOX2) in the halotolerant Myxococcus fulvus. Both enzymes share a low degree of amino acid conservation with well-characterized eukaryotic lipoxygenase isoforms but they involve the catalytically essential iron cluster. Here, we cloned the MF-LOX1 cDNA, expressed the corresponding enzyme as N-terminal hexa-his-tag fusion protein, purified the recombinant enzyme to electrophoretic homogeneity, and characterized it with respect to its protein-chemical and enzymatic properties. We found that M. fulvus expresses a catalytically active intracellular lipoxygenase that converts arachidonic acid and other polyunsaturated fatty acids enantioselectively to the corresponding n-9 hydroperoxy derivatives. The enzyme prefers C₂₀ - and C₂₂ -polyenoic fatty acids but does not exhibit significant membrane oxygenase activity. The possible biological relevance of MF-LOX1 will be discussed in the context of the suggested concepts of other bacterial lipoxygenases.

A comparative study of effect of autograft compared with allograft anterior cruciate ligament reconstruction on expressions of LOXs and MMPs

The present study aimed to compare the effect of autograft or allograft anterior cruciate ligament (ACL) reconstruction on the expressions of lipoxygenases (LOXs) and matrix metalloproteinases (MMPs) in a New Zealand white rabbit model. New Zealand white rabbits were divided randomly into control, sham, autograft and allograft groups. At the 4th and 8th week after operation, biomechanical testing was performed to measure the primary length, cross-sectional area, maximum tensile load and stiffness of ACL, and HE staining was used to observe cell morphology and fibre alignment of ACL. At the 2nd, 4th and 8th week after operation, quantitative real-time PCR (qRT-PCR), Western blotting and immunohistochemistry were applied to detect LOXs and MMPs expressions, and expressions of adenomatous polyposis coli (APC)/Wnt signalling pathway-related proteins. At the 4th and 8th week after operation, the maximum tensile load and stiffness were higher in the autograft group than in the allograft group, and the values at the 8th week were higher than those at the 4th week after operation. The fibroblast proliferation in the allograft group was more significant than that in the autograft group. Compared with the control group, LOXs and MMPs expressions and the positive expression rates of LOXs and MMPs proteins were elevated, and the values in the allograft group were higher than those in the autograft group at all time points. At 8th week after operation, compared with the autograft group, Wnt expression was higher and APC expression was lower in the allograft group. Autograft and allograft ACL reconstruction can promote LOXs and MMPs expressions by activating the APC/Wnt signalling pathway.

Production of 10R-hydroxy unsaturated fatty acids from hempseed oil hydrolyzate by recombinant Escherichia coli cells expressing PpoC from Aspergillus nidulans

The first and second preferred substrates of recombinant Escherichia coli cells expressing 10R-dioxygenase (PpoC) from Aspergillus nidulans and the purified enzyme were linoleic acid and α-linolenic acid, respectively. PpoC in cells showed higher thermal and reaction stabilities compared to purified PpoC. Thus, 10R-hydroxy unsaturated fatty acids were produced from linoleic acid, α-linolenic acid, and hempseed oil hydrolyzate containing linoleic acid and α-linolenic acid as substrates by whole recombinant cells expressing PpoC. The optimal reaction conditions for the production of 10R-hydroxy-8E,12Z-octadecadienoic acid (10R-HODE) were pH 8.0, 30 °C, 250 rpm, 5 % (v/v) dimethyl sulfoxide, 5 g l(-1) linoleic acid, and 60 g l(-1) cells in 100-ml baffled flask. Under these conditions, whole recombinant cells expressing PpoC produced 2.7 g l(-1) 10R-HODE from 5 g l(-1) linoleic acid for 40 min, with a conversion yield of 54 % (w/w) and a productivity of 4.0 g l(-1) h(-1); produced 2.2 g l(-1) 10R-hydroxy-8E,12Z,15Z-octadecatrienoic acid (10R-HOTrE) from 3 g l(-1) α-linolenic acid for 30 min, with a conversion yield of 72 % (w/w) and a productivity of 4.3 g l(-1) h(-1); and produced 1.8 g l(-1) 10R-HODE and 0.5 g l(-1) 10R-HOTrE from 5 g l(-1) hempseed oil hydrolyzate containing 2.5 g l(-1) linoleic acid and 1.0 g l(-1) α-linolenic acid for 30 min, with a conversion yield of 74 and 51 % (w/w), respectively, and a productivity of 3.6 and 1.0 g l(-1) h(-1), respectively. To the best of our knowledge, this is the first report on the biotechnological production of 10R-hydroxy unsaturated fatty acids.