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

Abstract

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.

Furan fatty acid as an anti-inflammatory component from the green-lipped mussel Perna canaliculus

“…On the other hand, if an antioxidative fatty acid can be embedded into the lipid component, then its antioxidative effect would be more promising. Spiteller hypothesized that furan fatty acids (F-acids), which were first isolated from the northern pike in 1974 (22), are such naturally occurring antioxidative fatty acids that ameliorate the oxidative risk of the cellular membrane (23,24). Even though F-acid concentration is usually low, these fatty acids are widely distributed in plants and aquatic organisms (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36).…”

“…The unique structural feature of Facids is the tetraalkyl-substituted furan ring, which is a rarely observed skeleton in natural products. This electron-rich furan ring is susceptible to oxidation, and the subsequent ring opening generates dioxoene, which is highly reactive and further converted to other compounds (23,30). Actually, F-acids readily decompose during prolonged exposure to silica gel or in neat oil.…”

Synthesis and scavenging role of furan fatty acids

“…From the chemical properties of Fu-FAs, it is proposed that they can scavenge lipid peroxides, fatty acyl radicals, or even 1 O 2 (13)(14)(15). The loss of 19Fu-FA when cells generate 1 O 2 is, to our knowledge, the first report of their potential role as scavengers of ROS in bacteria.…”

“…Despite the proposed roles of Fu-FAs, little is known about how they are synthesized (13). We report on proteins needed for the conversion of cis unsaturated fatty acids to 19Fu-FA.…”

“…Based on their chemical properties, it is proposed that Fu-FAs could provide bilayer protection against radicals or organic peroxides that reduce membrane function (13)(14)(15). The oxygen atom within Fu-FAs also provides a functional group for modifications that could increase their industrial value (13).…”