chemistry

Furan fatty acids

Furan fatty acids is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Furan fatty acids rather than just read about it. In short: Furan fatty acids are a group of fatty acids that contain a furan ring. To this furan ring, an unbranched carboxylic acid and, at another position, an alkyl residue are attached.

Key takeaways

Furan fatty acids belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Furan fatty acids to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Furan fatty acids from memory before moving on to harder problems.

Reference excerpt

Furan fatty acids are a group of fatty acids that contain a furan ring. To this furan ring, an unbranched carboxylic acid and, at another position, an alkyl residue are attached. Natural furan fatty acids are mono- or di-methylated on the furan ring. Furan fatty acids can be found in a variety of plant and animal species. Carboxy-substituted furan fatty acids are known as urofuran acids. Urofuran fatty acids are metabolic products of furan fatty acids and can be detected, for example, in human urine.

Occurrence Furan fatty acids are found mainly in the liver fat of fish, in crustaceans and horn corals. They can also be found in the liver of cattle and rats, as well as in human blood; either in free form or in triglycerides or esterified to cholesterol. In fish, the concentration of furan fatty acids is particularly high in the liver after hunger periods. Furan fatty acids can be detected in a variety of organisms and products such as butter and butter oil. It is now assumed that this class of compounds is ubiquitous. Furan fatty acids in animals are based on the uptake and accumulation of furan fatty acids from plant constituents. In human blood, the total furan fatty acid content is about 50 ng/ml. Per day, a person separates between 0.5 and 3 mg of urofuran acids - the metabolic product of the furans acids. Animals are not able to synthesize furan fatty acids. Larger amounts of furan fatty acids are produced mainly by algae, but also some plants and microorganisms. These serve fish and mammals as food. The furan fatty acids thus absorbed are incorporated into phospholipids and cholesterol esters.

Function and physiological effects

Furan fatty acids are reactive compounds. They are easily oxidizable by photooxygenation, autoxidation, or catalyzed by lipoxygenase-1. Upon the exposure to light, the aroma 3-methyl-2,4-nonanedione (MND) is formed from furan fatty acids in the reaction with singlet oxygen, which has a hay-like odor and is found, for example, in green tea. Furan fatty acids are very effectively acting as radical scavengers. In this process dioxoenoic fatty acids are formed, which are by themselves very unstable and form thioethers with thiols such as cysteine or glutathione. As potent antioxidants, they specifically trap hydroxyl radicals. It is therefore believed that this is in different biological systems their main function. They also inhibit the singlet oxygen-induced hemolysis of red blood cells (red blood cell disintegration). Plants and algae produce furan fatty acids during the biosynthesis from polyunsaturated fatty acids (PUFA). These are seemingly used in these organisms as protection against free radicals generated by sunlight.

Occasionally it is speculated that the health-promoting properties originally attributed to omega-3 fatty acids may not be based on themself, but on the furan fatty acids also present in the fish. A clinical trial of isolated omega-3 fatty acids such as eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) in patients who have had a myocardial infarction previously showed no significant difference in cardiovascular effects compared to a placebo. The exact pathological effects of furan fatty acids have not yet been clarified in detail and are the subject of current research. In addition to the antioxidant effect, anti-tumor (against malignant tumors) and antithrombotic effects (anti-thrombosis) are also suspected. In 2002, xenohormonal properties were observed for the two furan fatty acids 9,(12)-oxy-10,13-dihydroxystearic acid and 10,(13)-oxy-9,12-dihydroxystearic acid. In vitro experiments on MCF-7 cells (breast cancer cells with estrogen receptor) revealed mitogenic properties as well as an influence on estrus. In the latter case, the transition to metestrus was initiated. In vivo, a reduction in mating willingness was observed after intake of furan fatty acids on female color rats. However, neither estrogen nor anti-estrogenic activity has been demonstrated. Chickens were found to have no adverse effects on feeding, fertility, egg weight, eggshell thickness, and other reproductive parameters after the intake of furan fatty acids.

History Furan fatty acids were first detected in 1966 by L. J. Morris and colleagues as part of an oil derived from seeds of Exocarpus cupressiformis (a sandalwood-type plant). Years later, other analysis methods showed that the furan fatty acid 9,12-epoxyoctadeca-9,11-dienoic acid was in fact not contained in the oil of Exocarpus cupressiformis as described by Morris. Instead, it was formed during the sample preparation used by Morries and colleagues for the argentation chromatography by oxidation of hydroxyfatty acids, in a base-catalyzed transesterification. In 1974, furan fatty acids were first identified in pike (Esox lucius) by Robert L. Glass and colleagues using coupled gas chromatography–mass spectrometry (GC-MS).

Literature N. Hinrichsen: "Synthese und Analytik von Furanfettsäuren". Dissertation, Universität Hamburg, 2009, ISBN 3-86853-028-2 Dembitsky, V. M.; Rezanka, T. (1996). "Furan fatty acids of some brackish invertebrates from the Caspian sea". Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 114 (3): 317–320. doi:10.1016/0305-0491(96)00063-6. Prinsep, MR; Blunt, JW; Munro, MH (1994). "Isolation of the furan fatty acid, (8Z,11Z,14Z,17Z)-3,6-epoxyeicos-3,5,8,11,14,17-hexenoic acid from the New Zealand sponge Hymeniacidon hauraki". J Nat Prod. 57 (11): 1557–9. doi:10.1021/np50113a014. PMID 7853004. Wahl, H. G. (1988). "Die Bedeutung von Furanfettsäuren als Inhaltsstoffe von Fischölpräparaten". GIT Labor-Fachzeitschrift. 4: 368–372. Ishii, K; Okajima, H; Okada, Y; Watanabe, H (1988). "Studies on furan fatty acids of salmon roe phospholipids". J Biochem. 103 (5): 836–9. doi:10.1093/oxfordjournals.jbchem.a122356. PMID 3182753. Spiteller, G. (1987). "Furanfettsäuren". Nachrichten aus Chemie, Technik und Laboratorium. 35 (12): 1240–1243. doi:10.1002/nadc.19870351204. Rahn, C. H.; et al. (1979). "Synthesis of naturally occurring furan fatty acids". The Journal of Organic Chemistry. 44 (19): 3420–3424. doi:10.1021/jo01333a036. Glass, RL; Krick, TP; Sand, DM; Rahn, CH; Schlenk, H (1975). "Furanoid fatty acids from fish lipids". Lipids. 10 (11): 695–702. doi:10.1007/bf02532763. PMID 1196019. S2CID 4052488. R. Jónsdóttir, P. Hamaguchi, G. Ólafsdóttir, T. Wang: "Antioxidants from Icelandic marine sources." (PDF-File; 429 kB), May 2010.

References

Illustrations

Worked examples

Example 1 — a first encounter with Furan fatty acids

Start with the simplest possible case. Write down what Furan fatty acids claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Furan fatty acids before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Furan fatty acids ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Furan fatty acids

In research: Furan fatty acids appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Furan fatty acids in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Furan fatty acids is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fatty acids, Furans, so understanding it makes those chapters shorter.
In everyday life: Look for Furan fatty acids outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Furan fatty acids in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Furan fatty acids means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Furan fatty acids out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Furan fatty acids in simple terms?

Furan fatty acids are a group of fatty acids that contain a furan ring. To this furan ring, an unbranched carboxylic acid and, at another position, an alkyl residue are attached.

Why does Furan fatty acids matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Furan fatty acids?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Furan fatty acids.