Methylation of the ß-positions of the furan ring in F-acids

Scheinkönig, Josef; Hannemann, Kerstin; Spiteller, Gerhard

doi:10.1016/0005-2760(94)00169-y

Cited by 9 publications

(7 citation statements)

References 19 publications

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“…The position of the methyl group was determined after hydrogenation (in the presence of Pd as catalyst) (Fig. 4B), thanks to the THF-specific ring cleavage at m/z 286 enabling the unambiguous localization of the methyl substituent (38).…”

Section: Resultsmentioning

confidence: 99%

GC‐MS structural characterization of fatty acids from marine aerobic anoxygenic phototrophic bacteria

Rontani

Christodoulou

Koblížek

2005

Lipids

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The FA composition of 12 strains of marine aerobic anoxygenic phototrophic bacteria belonging to the genera Erythrobacter, Roseobacter, and Citromicrobium was investigated. GC-MS analyses of different types of derivatives were performed to determine the structures of the main FA present in these organisms. All the analyzed strains contained the relatively rare 11-methyloctadec-12-enoic acid, and three contained 12-methyl-octadec-11-enoic acid, which has apparently never been reported before. High amounts of the very unusual octadeca-5,11-dienoic acid were present in 9 of the 12 strains analyzed. A FA containing a furan ring was detected in three strains. Analytical data indicated that this FA was 10,13-epoxy-11-methyloctadeca-10,12-dienoic acid. A very interesting enzymatic peroxidation of the allylic carbon 10 of cis-vaccenic acid was observed in three strains. Deuterium labeling and GC-MS analyses enabled us to demonstrate that this enzymatic process involves the initial dioxygenase-mediated formation of 10-hydroperoxyoctadec-11(cis)-enoic acid, which is then isomerized to 10-hydroperoxyoctadec-11(trans)-enoic acid and converted to the corresponding hydroxyacids and oxoacids. Different biosynthetic pathways were proposed for these different compounds.

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Section: Resultsmentioning

confidence: 99%

GC‐MS structural characterization of fatty acids from marine aerobic anoxygenic phototrophic bacteria

Rontani

Christodoulou

Koblížek

2005

Lipids

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“…It was thus recognized that plants synthesize the basic skeleton of F-acids from acetate (98). The methyl groups in the β-position of the furan ring originate from methionine (99,100), and the furan oxygen is derived from air (101). Originally, it was assumed that LA (12) was the precursor of the carbon skeleton of F-acids having a pentyl side chain by generation of a hydroperoxide in position 13, whereas F-acids with a propyl side chain were hypothesized to be derived from a hydroperoxide in position 12 of linolenic acid (47).…”

Section: Biosynthesismentioning

confidence: 99%

Furan fatty acids: Occurrence, synthesis, and reactions. Are furan fatty acids responsible for the cardioprotective effects of a fish diet?

Spiteller

2005

Lipids

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Furan FA (F-acids) are tri- or tetrasubstituted furan derivatives characterized by either a propyl or pentyl side chain in one of the alpha-positions; the other is substituted by a straight long-chain saturated acid with a carboxylic group at its end. F-acids are generated in large amounts in algae, but they are also produced by plants and microorganisms. Fish and other marine organisms as well as mammals consume F-acids in their food and incorporate them into phospholipids and cholesterol esters. F-acids are catabolized to dibasic urofuran acids, which are excreted in the urine. The biogenetic precursor of the most abundant F-acid, F6, is linoleic acid. Methyl groups in the beta-position are derived from adenosylmethionine. Owing to the different alkyl substituents, synthesis of F-acids requires multistep reactions. F-acids react readily with peroxyl radicals to generate dioxoenes. The radical-scavenging ability of F-acids may contribute to the protective properties of fish and fish oil diets against mortality from heart disease.

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“…Hydroxylases, lipooxygenases, or other enzymes have been proposed or shown to incorporate an oxygen atom into the furan ring of terpenoids, antimicrobials, and other compounds ( 14 , 22 , 30 – 32 ). The source of the oxygen atom in the FuFA rings is O 2 ; however, the enzyme(s) involved is unknown ( 33 , 34 ).…”

Section: Discussionmentioning

confidence: 99%

A bacterial biosynthetic pathway for methylated furan fatty acids

Lemke

Olson

Morse

et al. 2020

Journal of Biological Chemistry

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Fatty acids play many important roles in cells and also in industrial processes. Furan fatty acids (FuFAs) are present in the lipids of some plant, fish, and microbial species and appear to function as second messengers in pathways that protect cells from membrane-damaging agents. We report here the results of chemical, genetic, and synthetic biology experiments to decipher the biosynthesis of the monomethylated FuFA, methyl 9-(3-methyl-5-pentylfuran-2-yl) nonanoate (9M5-FuFA), and its dimethyl counterpart, methyl 9-(3,4-dimethyl-5-pentylfuran-2-yl) nonanoate (9D5-FuFA), in two α-proteobacteria. Each of the steps in FuFA biosynthesis occurs on pre-existing phospholipid fatty acid chains, and we identified pathway intermediates and the gene products that catalyze 9M5-FuFA and 9D5-FuFA synthesis in Rhodobacter sphaeroides 2.4.1 and Rhodopseudomonas palustris CGA009. One previously unknown pathway intermediate was a methylated diunsaturated fatty acid, (10E,12E)-11-methyloctadeca-10,12-dienoic acid (11Me-10t,12t-18:2), produced from (11E)-methyloctadeca-11-enoic acid (11Me-12t-18:1) by a newly identified fatty acid desaturase, UfaD. We also show that molecular oxygen (O2) is the source of the oxygen atom in the furan ring of 9M5-FuFA, and our findings predict that an O2-derived oxygen atom is incorporated into 9M5-FuFA via a protein, UfaO, that uses the 11Me-10t,12t-18:2 fatty acid phospholipid chain as a substrate. We discovered that R. palustris also contains a SAM-dependent methylase, FufM, that produces 9D5-FuFA from 9M5-FuFA. These results uncover the biochemical sequence of intermediates in a bacterial pathway for 9M5-FuFA and 9D5-FuFA biosynthesis and suggest the existence of homologs of the enzymes identified here that could function in FuFA biosynthesis in other organisms.

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Methylation of the ß-positions of the furan ring in F-acids

Cited by 9 publications

References 19 publications

GC‐MS structural characterization of fatty acids from marine aerobic anoxygenic phototrophic bacteria

GC‐MS structural characterization of fatty acids from marine aerobic anoxygenic phototrophic bacteria

Furan fatty acids: Occurrence, synthesis, and reactions. Are furan fatty acids responsible for the cardioprotective effects of a fish diet?

A bacterial biosynthetic pathway for methylated furan fatty acids

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