LCPUFAs Trans-Esterification

Applications of LCPUFA transesterification

Enrichment of high-value LCPUFAs: Transesterification is used to produce and concentrate specific LCPUFAs, such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), from natural oils. In one example, enzymatic transesterification in a supercritical carbon dioxide medium was used to enrich fish oil with omega-3 PUFAs.

The overall reaction is a reversible process where one molecule of triglyceride and three molecules of alcohol react to produce one molecule of glycerol and three molecules of fatty acid alkyl esters (e.g., FAME or FAEE).

An alcohol, typically methanol or ethanol, which provides the new ester group.A catalyst, which can be a chemical (an acid or base) or a biological enzyme (lipase).

Chemical transesterification

This method uses strong acids (like hydrochloric or sulfuric acid) or strong bases (like sodium hydroxide) as a catalyst.

Transesterification of long-chain polyunsaturated fatty acids (LCPUFAs) is a chemical reaction that produces new esters from LCPUFA-containing triglycerides (fats) or phospholipids. The process involves exchanging the fatty acid chains attached to the glycerol backbone with an alcohol, often creating valuable fatty acid ethyl esters (FAEEs) or fatty acid methyl esters (FAMEs). This technique is commonly used to produce nutraceuticals or biodiesel.

For transesterification of long-chain polyunsaturated fatty acids (LCPUFAs), nitrogen is used to provide an inert atmosphere that prevents the oxidation of these sensitive compounds. LCPUFAs are highly susceptible to oxidation due to their double bonds, which can compromise product quality.

Prevents oxidation: LCPUFAs are very sensitive to oxygen, which can cause them to degrade and lose their nutritional value. During transesterification, the reaction mixture is heated and stirred, which increases the potential for oxygen exposure. By blanketing the reactor with an inert gas like nitrogen, the oxygen is displaced, thereby preserving the integrity of the LCPUFAs. This process is known as nitrogen purging.

Direct modulation via formation of lipid amides

Trans-esterification is the process of exchanging the acyl group of an ester. The mechanism typically involves alcohol, but amino alcohols or other nitrogen-containing compounds derived from amino acids can also act as the exchange partner, forming an amide bond instead.

Amino acid nitrogen modulates the trans-esterification of long-chain polyunsaturated fatty acids (LCPUFAs) by influencing metabolic pathways and acting as a reactant in the formation of lipid amides.

Amino acid metabolism and lipid synthesis: Excess amino acid carbon skeletons (after the removal of nitrogen) can be converted into acetyl-CoA, a primary building block for fatty acid synthesis. Under conditions of nitrogen limitation, the flux of carbon through amino acid catabolism is increased, feeding the synthesis of fatty acids.
mTOR signaling: The mammalian target of rapamycin (mTOR) is a protein complex that senses amino acid availability. Under conditions of amino acid starvation, mTOR signaling is suppressed, which subsequently decreases fatty acid synthesis. Conversely, high amino acid levels can activate mTOR to promote lipid synthesis.

Carnitine is a nitrogen-containing compound whose synthesis requires vitamin C as a cofactor. Together, they are essential for fatty acid metabolism and energy production. Nitrogen plays a direct role in carnitine's molecular structure and is a component of the amino acids used for its creation.

MCTs and carnitine: Unlike LCTs, medium-chain triglycerides are small enough to enter the mitochondria directly without needing the carnitine shuttle.

Carbohydrates can be converted into hydrocarbons using specialized metabolic pathways in microorganisms, a process that requires electron and hydrogen donors. While the human body uses carbohydrates for energy via glycolysis and the Krebs cycle.

The role of electron and hydrogen donors

The conversion of carbohydrates, which contain oxygen, into oxygen-free hydrocarbons is a reduction process that requires a source of electrons and hydrogen.

Conversion to acetyl-CoA: The sugar is metabolized via glycolysis to produce pyruvate, which is then converted into acetyl-CoA. Acetyl-CoA is a central hub in metabolism, serving as a precursor for both energy production and the synthesis of fatty acids.