10(S )-Hydroxy-8(E )-octadecenoic acid, an intermediate in the conversion of oleic acid to 7,10-dihydroxy-8(E )-octadecenoic acid

Antiproliferative Fatty Acids Isolated from the Polypore Fungus Onnia tomentosa

Onnia tomentosa is a widespread root rot pathogen frequently found in coniferous forests in North America. In this study, the potential medicinal properties of this wild polypore mushroom collected from north–central British Columbia, Canada, were investigated. The ethanol extract from O. tomentosa was found to exhibit strong antiproliferative activity. Liquid–liquid extraction and bioactivity-guided fractionation, together with HPLC-MS/MS and 1D/2D NMR analyses of the ethanol extract of O. tomentosa, led to the identification of eight known linoleic oxygenated fatty acids (1.1–1.4 and 2–5), together with linoleic (6) and oleic acids (7). The autoxidation of linoleic acid upon isolation from a natural source and compound 5 as an autoxidation product of linoleic acid are reported here for the first time. GC-FID analysis of O. tomentosa, Fomitopsis officinalis, Echinodontium tinctorium, and Albatrellus flettii revealed linoleic, oleic, palmitic, and stearic acids as the major fatty acids. This study further showed that fatty acids were the major antiproliferative constituents in the ethanol extract from O. tomentosa. Linoleic acid and oleic acid had IC50 values of 50.3 and 90.4 µM against human cervical cancer cells (HeLa), respectively. The results from this study have implications regarding the future exploration of O. tomentosa as a possible edible and/or medicinal mushroom. It is also recommended that necessary caution be taken when isolating unstable fatty acids from natural sources and in interpreting the results.

Production of 7,10-dihydroxy-8(E)-octadecenoic acid using cell-free supernatant of Pseudomonas aeruginosa

Cell-free synthesis has been adopted in the bioconversion process due to its known advantages, such as fast production rate, high product content, and no substrate/product inhibition effect. In this study, the cell-free supernatant of Pseudomonas aeruginosa was used to improve the production of 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) from oleic acid. DOD production using cell-free supernatant demonstrated reduction in bioconversion duration and higher product concentration than conventional method using whole cell culture. The maximum DOD concentration (6.41 g/L) was obtained after 36 h of biotransformation using 1 % v/v oleic acid as a substrate with a productivity of 0.178 g/L/h and a yield of 74.8 %. DOD concentration, productivity, and yield using cell-free supernatant were 2.12, 7.12, and 2.22 times higher, respectively, than using the conventional whole cell culture method. Of the carbon and nitrogen sources used in pre-culture, galactose and sodium glutamate along with diammonium phosphate were found to be the most effective for DOD production. An incubation temperature of 27 °C and pH 8.0 were found to be most favorable for DOD production. In addition, sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis demonstrated the presence of enzymes related to DOD production in the cell-free supernatant, which was substantiated by performing DOD production experiment using the supernatant enzymes extracted from protein gel bands with oleic acid as a substrate. To the best of our knowledge, this is the first report on DOD production using a cell-free supernatant and verifying the existence of the relevant enzymes in the cell-free supernatant. Compared to whole cell process, cell-free DOD production holds several advantages, including higher DOD productivity which could be beneficial for large-scale production.

Microbial Conversion of Vegetable Oil to Hydroxy Fatty Acid and Its Application to Bio-Based Polyurethane Synthesis

New polyurethanes were synthesized based on dihydroxy fatty acid obtained by the microbial conversion of olive oil. Monounsaturated 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) was produced from olive oil by Pseudomonas aeruginosa PR3 and reacted with hexamethylene diisocyanate (HMDI) at different ratios to form polyurethanes. Fourier transform infrared spectroscopy and gas chromatography/mass spectrometry confirmed the synthesis of DOD. The thermal and tensile properties of the polyurethanes were investigated by differential scanning calorimetry, thermogravimetric analysis, and a universal testing machine. At an isocyanate/hydroxyl ratio of 1.4, the polyurethane exhibited an elongation at break of 59.2% and a high tensile strength of 37.9 MPa. DOD was also mixed with polycaprolactone diol or polyethylene glycol at different weight ratios and then reacted with HMDI to produce new polyurethanes of various properties. These polyurethanes displayed higher elongation at break and good thermal stability. This is the first report on the synthesis of polyurethanes based on DOD produced by the microbial conversion of vegetable oil.

Yield and kinetic constants estimation in the production of hydroxy fatty acids from oleic acid in a bioreactor by Pseudomonas aeruginosa 42A2

We modelled the production of hydroxy fatty acids from oleic acid by Pseudomonas aeruginosa 42A2 in a bioreactor with a non-dispersive aeration system. First, we designed an adapted wetted-wall gas-absorption column, offering a k La value of 39.9 h(-1), to enhance oxygen absorption in the culture media and prevent foam formation. Then, we analysed different kinetic models to simulate the yield coefficients and the kinetic constants in this bacterial transformation. Monod model fitting (μ max1 = 0.51 h(-1), K S1 = 1.60 C-mol l(-1), μ max2 = 0.12 h(-1), K S2 = 0.035 C-mol l(-1), and k 2 = 0.033 h(-1)) showed a good accuracy with the experimental data sets and was chosen for its simplicity. Lastly, mass balances were carried out to establish the stoichiometry of this biotransformation with the following yield coefficients, Υ X/OA, Υ X/(10S)-HPOME and Υ (10S)-HPOME/(7S10S)-HPOME of 0.172, 0.347 and 2.388 C-mol C-mol(-1), respectively.

Production of hydroxy fatty acids by microbial fatty acid-hydroxylation enzymes

Hydroxy fatty acids are widely used in chemical, food, and cosmetic industries as starting materials for the synthesis of polymers and as additives for the manufacture of lubricants, emulsifiers, and stabilizers. They have antibiotic, anti-inflammatory, and anticancer activities and therefore can be applied for medicinal uses. Microbial fatty acid-hydroxylation enzymes, including P450, lipoxygenase, hydratase, 12-hydroxylase, and diol synthase, synthesize regio-specific hydroxy fatty acids. In this article, microbial fatty acid-hydroxylation enzymes, with a focus on region-specificity and diversity, are summarized and the production of mono-, di-, and tri-hydroxy fatty acids is introduced. Finally, the production methods of regio-specific and diverse hydroxy fatty acids, such as gene screening, protein engineering, metabolic engineering, and combinatory biosynthesis, are suggested.

Production of long-chain hydroxy fatty acids by microbial conversion

Hydroxy fatty acids (HFAs) are very important chemicals for versatile applications in biodegradable polymer materials and cosmetic and pharmaceutical industries. They are difficult to be synthesized via chemical routes due to the inertness of the fatty acyl chain. In contrast, these fatty acids make up a major class of natural products widespread among bacteria, yeasts, and fungi. A number of microorganisms capable of producing HFAs from fatty acids or vegetable oils have been reported. Therefore, HFAs could be produced by biotechnological strategies, especially by microbial conversion processes. Microorganisms could oxidize fatty acids either at the terminal carbon or inside the acyl chain to produce various HFAs, including α-HFAs, β-HFAs, mid-position HFAs, ω-HFAs, di-HFAs, and tri-HFAs. The enzymes and their encoded genes responsible for the hydroxylation of the carbon chain have been identified and characterized during the past few years. The involved microbes and catalytic mechanisms for the production of different types of HFAs are systematically demonstrated in this review. It provides a better view of HFA biosynthesis and lays the foundation for further industrial production.

Production of a novel 9,12-dihydroxy-10(E)-eicosenoic acid from eicosenoic acid by Pseudomonas aeruginosa PR3

Microbial conversions of unsaturated fatty acids often generate polyhydroxy fatty acids, giving them new properties such as higher viscosity and reactivity. A bacterial strain Pseudomonas aeruginosa (PR3) has been intensively studied to produce mono-, di-, and trihydroxy fatty acids from different 9-cis-monoenoic fatty acids such as oleic acid, ricinoleic acid, and palmitoleic acid. However, from the results and the postulated similar metabolic pathways involved in these transformations, it was assumed that the enzyme system involved in transformation of the monoenoic fatty acid by strain PR3 could utilize fatty acids with different chain lengths and locations of the double bond. In this study was used as a substrate for bioconversion by strain PR3 eicosenoic acid (C20:1, ω-9) containing a singular cis double bond at different positions from the carboxyl end as oleic acid, and it was confirmed that PR3 could produce a novel 9,12-dihydroxy-10(E)-eicosenoic acid (DED) with 6.2% yield from eicosenoic acid. The structure of DED was confirmed using GC-MS, FTIR, and NMR analyses. DED production was maximized at 72 h after the substrate was added to the 24 h culture. Some other nutritional factors were also studied for optimal production of DED.

Biochemical characterization of the oxygenation of unsaturated fatty acids by the dioxygenase and hydroperoxide isomerase of Pseudomonas aeruginosa 42A2

We have studied oxygenation of fatty acids by cell extract of Pseudomonas aeruginosa 42A2. Oleic acid ((9Z)-18:1) was transformed to (10S)-hydroperoxy-(8E)-octadecenoic acid ((10S)-HPOME) and to (7S,10S)-dihydroxy-(8E)-octadecenoic acid (7,10-DiHOME). Experiments under oxygen-18 showed that 7,10-DiHOME contained oxygen from air and was formed sequentially from (10S)-HPOME by isomerization. (10R)-HPOME was not isomerized. The (10S)-dioxygenase and hydroperoxide isomerase activities co-eluted on ion exchange chromatography and on gel filtration with an apparent molecular size of approximately 50 kDa. 16:1n-7, 18:2n-6, and 20:1n-11 were also oxygenated to 7,10-dihydroxy fatty acids, and (8Z)-18:1 was oxygenated to 6,9-dihydroxy-(7E)-octadecenoic acid. A series of fatty acids with the double bond positioned closer to ((6Z)-18:1, (5Z,9Z)-18:2) or more distant from the carboxyl group ((11Z)-, (13Z)-, and (15Z)-18:1) were poor substrates. The oxygenation mechanism was studied with [7S-(2)H]18:1n-9, [7R-(2)H]18:2n-6, and [8R-(2)H]18:2n-6 as substrates. The pro-R hydrogen at C-8 was lost in the biosynthesis of (10S)-HPODE, whereas the pro-S hydrogen was lost and the pro-R hydrogen was retained at C-7 during biosynthesis of the 7,10-dihydroxy metabolites. Analysis of the fatty acid composition of P. aeruginosa revealed relatively large amounts of (9E/Z)-16:1 and (11E/Z)-18:1 and only traces of 18:1n-9. We found that (11Z)-18:1 (vaccenic acid) was transformed to (11S,14S)-dihydroxy-(12E)-octadecenoic acid and to a mixture of 11- and 12-HPOME, possibly due to reverse orientation of (11Z)-18:1 at the active site compared with oleic acid. The reaction mechanism of the hydroperoxide isomerase suggests catalytic similarities to cytochrome P450.

Liquid chromatography/tandem mass spectrometric analysis of 7,10-dihydroxyoctadecenoic acid, its isotopomers, and other 7,10-dihydroxy fatty acids formed by Pseudomonas aeruginosa 42A2

Pseudomonas aeruginosa is an opportunistic pathogen, which oxidizes oleic acid to 7(S),10(S)-dihydroxy-8(E)-octadecenoic acid (7,10-(OH)(2)-18:1) of biological and industrial interest. Electrospray tandem mass spectrometric (MS/MS) analysis of hydroxylated fatty acids usually generates characteristic fragments containing the carboxylate anion and formed by alpha-cleavage at the oxidized carbon. These fragments indicate the positions of the hydroxyl group. In contrast, liquid chromatography (LC)/MS/MS analysis of 7,10-(OH)(2)-18:1 yielded a series of other ions with structural information. To study the fragmentation mechanism, we prepared (2)H- and (18)O-labeled isotopomers. We also performed MS(3) analysis of the major ions, and for comparison we generated the corresponding 7,10-dihydroxy metabolites of 16:1n-7, 18:2n-6, and 20:1n-11 with a protein extract of P. aeruginosa. The MS/MS spectra of 7,10-(OH)(2)-18:1 and its isotopomers, 7,10-(OH)(2)-16:1, and 7,10-(OH)(2)-20:1, contained a series of prominent fragments that all hold the omega end. The 8,9-double bond was not essential for this fragmentation, as 7,10-(OH)(2)-18:0, and its isotopomers, formed essentially the same fragments in the lower mass range. In contrast, 7,10-dihydroxy-8(E),12(Z)-octadecadienoic acid (7,10-(OH)(2)-18:2) fragmented by alpha-cleavage at the oxidized carbons with formation of carboxylate anions. Our results demonstrate that C(16)-C(20) fatty acids with a 7,10-dihydroxy-8(E) functionality undergo charge-driven fragmentation after charge migration to the omega-end, whereas the main ions of 7,10-(HO)(2)-18:2 retain charge at the carboxyl group.

Production of 7, 10-dihydroxy-8(E)-octadecenoic acid from triolein via lipase induction by Pseudomonas aeruginosa PR3

Hydroxy fatty acids (HFA) have gained importance because of their special properties such as higher viscosity and reactivity compared with other non-hydroxy fatty acids. The bacterial isolate Pseudomonas aeruginosa (PR3) was reported to produce mono-, di-, and trihydroxy fatty acids from different unsaturated fatty acids. Of those, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) was produced with high yield from oleic acid by PR3. Up to now, the substrates used for microbial HFA production were free fatty acids. However, it is possible to utilize triacylglycerides, specifically triolein containing three oleic groups, as a substrate by microbial enzyme system involved in HFA production from oleic acid. In this study we used triolein as a substrate and firstly report that triolein could be efficiently utilized by PR3 to produce DOD. Triolein was first hydrolyzed into oleic acid by the triolein-induced lipase and then the released oleic acid was converted to DOD by PR3. Results from this study demonstrated that natural vegetable oils, without being intentionally hydrolyzed, could be used as efficient substrates for the microbial production of value-added hydroxy fatty acids.

Production and identification of a novel compound, 7,10-dihydroxy-8(E)-hexadecenoic acid from palmitoleic acid by Pseudomonas aeruginosa PR3

Hydroxy fatty acids are considered as important value-added product for industrial application because of their special properties such as higher viscosity and reactivity. Microbial production of the hydroxy fatty acids from various fatty acid substrates have been actively studied using several microorganisms. The new bacterial isolate Pseudomonas aeruginosa (PR3) had been reported to produce mono-, di-, and tri-hydroxy fatty acids from different unsaturated fatty acids. Of those, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) and 7,10,12-trihydroxy-8(E)-octadecenoic acid (TOD) were produced from oleic acid and ricinoleic acid, respectively. Based on the postulated common metabolic pathway involved in DOD and TOD formation by PR3, it was assumed that palmitoleic acid containing a singular 9-cis double bond, common structural property sharing with oleic acid and ricinoleic acid, could be utilized by PR3 to produce hydroxy fatty acid. In this study, we tried to use palmitoleic acid as substrate for production of hydroxy fatty acid by PR3 and firstly confirmed that PR3 could produce 7,10-dihydroxy-8(E)-hexadecenoic acid (DHD) with 23% yield from palmitoleic acid. DHD production was peaked at 72 h after the substrate was added to the 24-h-culture.

The effect of bio-converted polyunsaturated fatty acids on the oxidation of TAG containing highly unsaturated fatty acids

Microbial modification of vegetable fatty acids can often lead to special changes in their structure and in biological function. A bacterial strain, Pseudomonas aeruginosa PR3, is known to carry out multiple hydroxylations on polyunsaturated fatty acids containing 1,4-cis, cis diene structural units, resulting in antibacterial activity. In this paper, in an effort to understand the overall mechanism involved in the varied biological functions of the complicated metabolites of bio-converted polyunsaturated fatty acids, we performed bioconversion of several polyunsaturated fatty acids using PR3, and determined their oxidative activities against fish oil. Bio-converted linoleic acid, eicosapentanoic acid, and docosahexanoic acid promoted effectively oxidation of fish oil. It is assumed that this oxidative effect could plausibly play an important role in the antimicrobial function of these bio-converted fatty acids.