Production of isomeric 9,10,13 (9,12,13)-trihydroxy-11E (10E)-octadecenoic acid from linoleic acid by Pseudomonas aeruginosa PR3

Trihydroxy unsaturated fatty acids with 18 carbons have been reported as plant self-defense substances. Their production in nature is rare and is found mainly in plant systems. Previously, we reported that a new bacterial isolate, Pseudomonas aeruginosa PR3, converted oleic acid and ricinoleic acid to 7,10-dihydroxy-8(E)-octadecenoic acid and 7,10,12-trihydroxy-8(E)-octadecenoic acid, respectively. Here we report that strain PR3 converted linoleic acid to two compounds: 9,10,13-trihydroxy-11(E)-octadecenoic acid (9,10,13-THOD) and 9,12,13-trihydroxy-10(E)-octadecenoic acid (9,12,13-THOD). Stereochemical analyses showed the presence of 16 different diastereomers — the maximum number possible. The optimum reaction temperature and pH for THOD production were 30°C and 7.0, respectively. The optimum linoleic acid concentration was 10 mg/ml. The most effective single carbon and nitrogen sources were glucose and sodium glutamate, respectively. However, when a mixture of yeast extract (0.05%), (NH₄)₂HPO₄ (0.2%), and NH₄NO₃ (0.1%) was used as the nitrogen source, THOD production was higher by 8.3% than when sodium glutamate was the nitrogen source. Maximum production of total THOD with 44% conversion of substrate was achieved at 72 h of incubation, after which THOD production plateaued up to 240 h. THOD production and cell growth increased in parallel with glucose concentration up to 0.3%, after which cell growth reached its maximum and THOD production did not increase. These results suggested that THODs were not metabolized by strain PR3. This is the first report of microbial production of 9,10,13- and 9,12,13-THOD from linoleic acid. Journal of Industrial Microbiology & Biotechnology (2000) 25, 109–115. Received 18 March 2000/ Accepted in revised form 09 June 2000     

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

Summary Previously, we reported the discovery of a new compound, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) which was produced from oleic acid by a new bacterial isolate PR3 [6,7]. The reaction is unique in that it involves a hydroxylation at two positions and a rearrangement of the double bond of the substrate molecule. Now, we have isolated another compound from the reaction mixture determined by GC/MS to be 10-hydroxy-8-octadecenoic acid (HOD). NMR and IR data indicate that the unsaturation is probablycis. The optimum pH and temperature for the production of HOD by strain PR3 were 6.5 and 30°C, about the same as those for DOD. However, the amount of HOD detected remained small throughout an 48-h reaction period during which the amount of DOD increased sharply. At 48 h of reaction, the ratio between HODDOD was 110. HOD may be an intermediate in the biosynthesis of DOD from oleic acid.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Production and identification of a novel compound, 7,10-dihydroxy-8(<Emphasis Type="Italic">E</Emphasis>)-hexadecenoic acid from palmitoleic acid by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> 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.     

Identification of NRRL strain B-18602 (PR3) as Pseudomonas aeruginosa and effect of phenazine 1-carboxylic acid formation on 7,10-dihydroxy-8(E)-octadecenoic acid accumulation

A new compound, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD), produced from oleic acid by a new bacterial isolate PR3, was discovered in 1991. We have now identified isolate PR3 as a strain of Pseudomonas aeruginosa by DNA reassociation studies. Strain PR3 also produced a crystalline yellowish compound the structure of which, as determined by GC/MS and NMR, is phenazine 1-carboxylic acid (PCA). In cultures of PR3, high PCA production was associated with low DOD accumulation.The mention of firm names or trade products does not imply that they are endorsed or recommended by the US Department of Agriculture over other firms or similar products not mentioned.     

Production of a new compound, 7,10-dihydroxy-8-(E)-octadecenoic acid from oleic acid byPseudomonas sp. PR3

Summary Sixty-two cultures from the ARS Culture Collection and 10 cultures isolated from soil and water samples collected in Illinois were screened for their ability to convert agricultural oils to value-added industrial chemicals. A new compound, 7,10-dihydroxy-8-(E)-octadecenoic acid (DOD) was produced from oleic acid by a new strain,Pseudomonas sp. PR3 isolated from a water sample in Morton, IL. Strain PR3 is a motile, small rod-shaped, Gram-negative bacterium. It has multiple polar flagellae and is oxidase-positive. Strain PR3 grows aerobically and cannot grow anaerobically. The strain produces white, smooth colonies on agar plate and no water-soluble pigment. The yield of the product was greater than 60%. The optimum time, pH and temperature for the production of DOD were: 2 days, 7.0, and 30°C, respectively. Glycerol and dextrose support the growth of strain PR3, but the cells grown from the former failed to catalyse the conversion of oleic acid to DOD. The production of DOD is unique in that it involves a hydroxylation at two positions and a rearrangement of the double bond of the substrate molecule.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Production of a Novel Compound, 7,10,12-Trihydroxy-8(E)-Octadecenoic Acid from Ricinoleic Acid by Pseudomonas aeruginosa PR3

The production and its potential use of a novel trihydroxy unsaturated fatty acid, 7,10,12-trihydroxy-8(E)-octadecenoic acid (TOD), were investigated. TOD was formed by Pseudomonas aeruginosa PR3 (NRRL B-18602) in a culture supplied with exogenous ricinoleic acid. The yield of TOD production was always higher in a rich culture medium than in minimal screening medium. Extending the conversion time from 48 to 72 h prior to lipid extraction led to a 65% reduction in yield, indicating that TOD was further metabolized by strain PR3 and that control of reaction time is important to achieving a maximum yield. The optimum culture density, reaction time, pH, temperature, and substrate concentration for the production of TOD were: 20–24 h culture growth, 48 h, 7.0, 25°C, and 1% (vol/vol), respectively. Under optimum conditions, the yield of TOD production was greater than 45%. TOD was found to be an antifungal agent most active against the fungus that causes blast disease in rice plants, the most important fungal disease affecting rice production worldwide. Received: 4 January 2001/Accepted: 6 February 2001     

Diversity of Oleic Acid,Ricinoleic Acid and Linoleic Acid Conversions Among <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> Strains*

Sixteen Pseudomonas aeruginosa strains, including patent strain NRRL B-18602, three recent isolates from composted materials amended with ricinoleic acid, and 12 randomly selected from the holdings of the ARS Culture Collection, were examined for their fatty acid converting abilities. The study examined the bioconversion of oleic acid to 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) and ricinoleic acid to 7,10,12-trihydroxy-8(E)-octadecenoic acid (TOD). A new DOD-like compound from linoleic acid was observed. All strains except NRRL B-247 exhibited varying levels of DOD production. NRRL B-1000, NRRL B-18602 and NRRL B-23258 with yields up to 84% were among the best DOD producers. TOD production generally paralleled DOD production at a relatively lower yield of up to 15%. Strains NRRL B-1000 and NRRL B-23260 were the best TOD producers. A DOD-like product in low yields was obtained from linoleic acid. The fatty acid bioconversion capability was related neither to growth rate nor to variation in the greenish pigmentation of the strains. Production of significant quantities of DOD and TOD from oleic and ricinoleic acids, respectively, appeared to be a characteristic trait of P. aeruginosa strains. A number of highly effective strains for DOD production were identified.     

A facile reactor process for producing 7,10-dihydroxy-8(E)-octadecenoic acid from oleic acid conversion by Pseudomonas aeruginosa

Pseudomonas aeruginosa strain PR3 (NRRL B-18602) converts oleic acid to a novel compound, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD). The bioconversion was scaled up in a 7-l bench-top, stirred-batch reactor to produce DOD for testing of potential industrial uses. Aeration was supplied continuously from the top through two ports on the headplate and periodically through a bottom sparger, in conjunction with the use of marine impellers for agitation. This unique aeration arrangement maintained the dissolved O₂ concentration in the 40–60% range during the period of maximal bioconversion and it also avoided excessive medium foaming during the reaction. Furthermore, the level of dissolved O₂ in the first 24 h of reaction played an important role in the initial rate of DOD production. DOD production reached a plateau after 72 h with a yield up to 100 g (or 50% recovery) from a total of 9 l medium from two reactors run simultaneously. The final culture broth was processed using newly adapted procedures in the pilot plant that included crystallization of DOD from ethyl acetate solution at –15°C. The newly developed bioprocess will serve as a platform for the scale-up production of other value-added products derived from vegetable oils and their component fatty acids.     

Environmental optimization for bioconversion of triolein into 7,10-dihydroxy-8(<Emphasis Type="Italic">E</Emphasis>)-octadecenoic acid by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> PR3

Hydroxy fatty acids (HFAs), originally found in small amount mainly from plant systems, are well known to have special properties such as higher viscosity and reactivity compared with other normal fatty acids. Recently, various microbial strains were tested to produce HFAs from different unsaturated fatty acids. Among those microbial strains tested, Pseudomonas aeruginosa PR3 are well known to utilize various unsaturated fatty acids to produce mono-, di-, and tri-HFAs. Previously, we reported that strain PR3 could utilize triolein as a substrate for the production of 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) via the induction of lipase activity (Chang et al., Appl Microbiol Biotechnol, 74:301–306, 2007). In this study, we focused on the development of the optimal environmental conditions for DOD production from triolein by PR3. Optimal initial medium pH and incubation temperature were pH 8.0 and 25°C, respectively. Magnesium ion was essentially required for DOD production. Optimal inoculum size, time for substrate addition, and substrate concentration were 1%, 12 to 24 h, and 300 mg, respectively.     

7,10-Dihydroxy-8(E)-octadecenoic acid produced by Pseudomonas 42A2: evaluation of different cultural parameters of the fermentation

A fermentation process for the microbial production of a new lipid surface-active compound, 7,10-dihydroxy-8 (E)-octadecenoic acid (OCD), has been established using a vegetable oil as carbon source in a coordinated carbon/nitrogen feed strategy. The surfactant was produced during the logarithmic growth phase. Aeration was the most critical parameter for product formation. Up to 7 g product/l was produced.The authors are with the Laboratorio de Microbiologia, Facultad de Farmacia, Avenida Diagonal 643, Universidad de Barcelona, 08028 Barcelona, Spain     

Production of a value-added hydroxy fatty acid, 7,10-dihydroxy-8(<Emphasis Type="Italic">E</Emphasis>)-octadecenoic acid,from high oleic safflower Oil by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> PR3

Hydroxy fatty acids (HFAs), originally obtained in small amounts from plant systems, are good examples of structurally modified lipids, and they render special properties such as higher viscosity and reactivity compared to normal fatty acids. Based on these properties, HFAs possess high industrial potential in a wide range of applications. Recently, various microbial strains were tested for the production of HFAs from different unsaturated fatty acids since HFA production is limited to plant systems. Among the microbial strains tested, Pseudomonas aeruginosa PR3 has been well studied for the production of 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) from oleic acid. Previously, we reported that strain PR3 could utilize triolein instead of oleic acid as a substrate for the production of DOD (Appl. Microbiol. Biotechnol. 2007, 74: 301–306). In this study, we focused on utilization of vegetable oil as a substrate for DOD production by PR3. Consequently, strain PR3 efficiently utilized high oleic safflower oil as a substrate for DOD production. Optimal initial medium pH and incubation time were pH 8.0 and 72 h, respectively. Optimal carbon and nitrogen sources were fructose and glutamine, respectively. Results from this study demonstrate that normal vegetable oils could be used as efficient substrates for the production of value-added HFAs by microbial bioconversion.     

Isolation and characterization of a lipoxygenase from Pseudomonas 42A2 responsible for the biotransformation of oleic acid into (S)-(E)-10-hydroxy-8-octadecenoic acid

The isolation of a new lipoxygenase-like (LOX-like) enzyme from Pseudomonas 42A2 and its characterization is described. The enzyme, located in the periplasm of the cell, which contained 0.55 mol of Fe2+ per mol of protein, is monomeric and has a molecular mass of 45 kDa. In the presence of oxygen, the enzyme converts oleic acid into (E)-10-hydroperoxy-8-octadecenoic acid (HPOD), which decomposes to the corresponding (E)-10-hydroxy-8-octadecenoic acid (HOD). The absolute configuration of this acid was determined as S on the basis of exciton-coupled CD data, and specific rotation and NMR analysis of the corresponding p -bromobenzoate derivative. The reaction in vivo leads to the dihydroxy derivative (E)-7,10-dihydroxy-8-octadecenoic acid (DHOD), so that the three hydroxy-fatty acids can be isolated from the culture medium. The activity of the enzyme was optimal between 25 and 30 degrees C and 44% of its activity still remained at 55 degrees C. Its optimal pH is 8.5-9; and the presence of magnesium ions increased LOX activity by 1.5. The activity of the LOX is highest in unsaturated fatty acids containing double bonds in position 9 (oleic, linoleic and linolenic acids), linoleic acid being preferred (100% activity) over linolenic (60.4%) and oleic acids (46%). However, kinetic studies showed that the affinity of the enzyme is similar for the three substrates.     

Production of 7, 10-dihydroxy-8(<Emphasis Type="Italic">E</Emphasis>)-octadecenoic acid from triolein via lipase induction by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> 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 of 10-Hydroxy-8(E)-Octadecenoic Acid from Oleic Acid Conversion by Strains of Pseudomonas aeruginosa

Eighteen Pseudomonas aeruginosa strains were examined for their ability to convert oleic acid to produce 10-hydroxy-8(E)-octadecenoic acid (HOD), which was structurally confirmed by GC-MS, NMR, and FTIR. There were no substantial amounts of other new compounds found in the fermentation broths in addition to HOD and 7,10-dihydroxy-8(E)-octadecenoic acid (DOD). The results demonstrated that P. aeruginosa strains possessed varying levels of activity for producing HOD. Under the experimental conditions, strain NRRL B-14938 isolated from sheep manure was the best HOD producer exhibiting the highest HOD to DOD product ratio in the medium most suitable for purifying HOD. Using strain B-14938 as a model system for further characterization, optimum conditions for producing HOD were found to be at 26°C and pH 7.0 after 60 h of reaction time using a medium containing EDTA as a chelating agent. This study has identified a high-yielding P. aeruginosa strain and provided the reaction characteristics needed to develop a scale-up production process of HOD for testing its properties and potential new uses.     

Production of 7,10-dihydroxy-8(<Emphasis Type="Italic">E</Emphasis>)-octadecenoic acid from olive oil by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> PR3

Microbial modification of naturally occurring materials is one of the efficient ways to add new values to them. Hydroxylation of free unsaturated fatty acids by microorganism is a good example of those modifications. Among microbial strains studied for that purpose, a new bacterial isolate Pseudomonas aeruginosa PR3 has been well studied to produce several hydroxy fatty acids from different unsaturated fatty acids. Of those hydroxy fatty acids, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) was efficiently produced from oleic acid by strain PR3. However, it was highly plausible to use vegetable oil containing oleic acid rather than free oleic acid as a substrate for DOD production by strain PR3. In this study, we firstly tried to use olive oil containing high content of oleic acid as a substrate for DOD production. DOD production from olive oil was confirmed by structural determination with GC, TLC, and GC/MS analysis. DOD production yield from olive oil was 53.5%. Several important environmental factors were also tested. Galactose and glutamine were optimal carbon and nitrogen sources, and magnesium ion was critically required for DOD production from olive oil. Results from this study demonstrated that natural vegetable oils containing oleic acid could be used as efficient substrate for the production of DOD by strain PR3.     

Synthesis of (S)-13-Hydroxy (2E,4E,8E)- and (2E,4E,8Z)-Tetradecatrienoic Acids

The syntheses of (S)-13-hydroxy-(2E,4E,8E)-tetradecatrienoic acid (1) and (2E,4E,8Z)-tetradecatrienoic acid (2) were carried out by using the Wittig reaction as the key step. The asymmetric center at C-13 and the double bond between C-8 and C-9 for natural compound 1 were reconfirmed as being of (S) configuration and E, respectively.

The relationship between the structure of the unsaturated hydroxy fatty acids and their inhibitory effect on the growth of lettuce was investigated.     

Synthesis and biological activity of hydroxylated derivatives of linoleic acid and conjugated linoleic acids

Allylic hydroxylated derivatives of the C18 unsaturated fatty acids were prepared from linoleic acid (LA) and conjugated linoleic acids (CLAs). The reaction of LA methyl ester with selenium dioxide (SeO₂) gave mono-hydroxylated derivatives, 13-hydroxy-9Z,11E-octadecadienoic acid, 13-hydroxy-9E,11E-octadecadienoic acid, 9-hydroxy-10E,12Z-octadecadienoic acid and 9-hydroxy-10E,12E-octadecadienoic acid methyl esters. In contrast, the reaction of CLA methyl ester with SeO₂ gave di-hydroxylated derivatives as novel products including, erythro-12,13-dihydroxy-10E-octadecenoic acid, erythro-11,12-dihydroxy-9E-octadecenoic acid, erythro-10,11-dihydroxy-12E-octadecenoic acid and erythro-9,10-dihydroxy-11E-octadecenoic acid methyl esters. These products were purified by normal-phase short column vacuum chromatography followed by high-performance liquid chromatography (HPLC). Their chemical structures were characterized by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectroscopy (NMR). The allylic hydroxylated derivatives of LA and CLA exhibited moderate in vitro cytotoxicity against a panel of human cancer cell lines including chronic myelogenous leukemia K562, myeloma RPMI8226, hepatocellular carcinoma HepG2 and breast adenocarcinoma MCF-7 cells (IC₅₀ 10-75 μM). The allylic hydroxylated derivatives of LA and CLA also showed toxicity to brine shrimp with LD₅₀ values in the range of 2.30-13.8 μM. However these compounds showed insignificant toxicity to honeybee at doses up to 100 μg/bee.     

Substrate selectivity of various lipases in the esterification of cis- and trans-9-octadecenoic acid

The substrate selectivity of numerous commercially available lipases from microorganisms, plants and animal tissue towards 9-octadecenoic acids with respect to the cis/trans configuration of the CC double bond was examined by the esterification of cis- and trans-9-octadecanoic acid (oleic and elaidic acid respectively) with n-butanol in n-hexane. A great number of lipases studied, e.g. those from Pseudomonas sp., porcine pancreas or Carica papaya, were unable to discriminate between the isomeric 9-octadecenoic acids. However, lipases from Candida cylindracea and Mucor miehei catalysed the esterification of oleic acid 3–4 times faster than the corresponding reaction of elaidic acid and therefore have a high preference for the cis isomer. Of all biocatalysts examined, only recombinant lipases from Candidaantarctica favoured elaidic acid as substrate. While the preference of Candida antarctica lipase B for the trans isomer was quite low, Candida antarctica lipase A had an extraordinary substrate selectivity and its immobilized enzyme preparation [Chirazyme L-5 (3) from Boehringer] esterified elaidic acid about 15 times faster than oleic acid. Received: 29 October 1998 / Received revision: 18 December 1998 / Accepted: 21 December 1998     

Factors Influencing the Production of a Novel Compound, 7,10-Dihydroxy-8(<Emphasis Type="Italic">E</Emphasis>)-octadecenoic Acid,by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> PR3 (NRRL B-18602) in Batch Cultures

Pseudomonas aeruginosa PR3 (NRRL B-18602) converts oleic acid to a novel compound, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD). Parameters that included medium volume, cell growth time, gyration speed, pH, substrate concentration, and dissolved oxygen concentration were evaluated for a scale-up production of DOD in batch cultures using Fernbach flasks and a bench-top bioreactor. Maximum production of about 2 g DOD (38% yield) was attained in Fernbach flasks containing 500 ml medium when cells were grown at 28°C and 300 rpm for 16–20 h and the culture was adjusted to pH 7 prior to substrate addition. Increases of medium volume and substrate concentration failed to enhance yield. When batch cultures were initially conducted in a reactor, excessive foaming occurred that made the bioconversion process inoperable. This was overcome by a new aeration mechanism that provided adequate dissolved oxygen to the fermentation culture. Under the optimal conditions of 650 rpm, 28°C, and 40–60% dissolved oxygen concentration, DOD production reached about 40 g (40% yield) in 4.5 L culture medium using a 7-L reactor vessel. This is the first report on a successful scale-up production of DOD. Received: 26 September 2002 / Accepted: 24 October 2002     

Acid-catalyzed transformation of 13(S)-hydroperoxylinoleic acid into epoxyhydroxyoctadecenoic and trihydroxyoctadecenoic acids

Acid treatment of (13S)-(9Z,11E)-13-hydroperoxy-9,11-octadecadienoic acid in tetrahydrofuran-water solvent afforded mainly (11R,12R,13S)-(Z)-12,13-epoxy-11-hydroxy-9-octadecenoic acid, diastereomeric (Z)-11,12,13-trihydroxy-9-octadecenoic acids and four isomers of (E)-9,12,13(9,10,13)-trihydroxy-10(11)-octadecenoic acid. Other minor products were oxooctadecadienoic, (E)-9(13)-hydroxy-13(9)-oxo-10(11)-octadecenoic and (E)-12-oxo-10-dodecenoic acids. A heterolytic mechanism for acid catalysis was indicated, even though most of the products characterized also have been observed as a result of homolytic decomposition of the hydroperoxide via an oxy radical. Most of the products found in this study have been observed as metabolites of (13S)-(9Z,11E)-13-hydroperoxy-9,11-octadecadenoic acid in biological systems, and analogous compounds have been reported as metabolites of (12S)-(5Z,8Z,10E, 14Z)-12-hydroperoxy-5,8,10,14-hydroperoxy-5,8,10,14-eicosatetraenoic acid in either blood platelets or lung tissue.