PALMITOLEIC ACID: STRUCTURE, FUNCTIONS, WHERE IT IS FOUND - BIOLOGY - 2024

The palmitoleic acid, cis -9-hexadecenoic acid, cis -palmitoleico acid, (Z) -9-hexadecenoic or hexadec-9-enoic acid, a monounsaturated fatty acid 16 carbon atoms belonging to the group of fatty acids omega 7, characterized by having a double bond (unsaturation) in the position corresponding to carbon atom number 7 from its ω end.

There are different types of omega (ω) fatty acids, of which omega-3, omega-9 and omega-12 stand out, which are polyunsaturated fatty acids (with more than one double bond). However, the group of omega 7 monounsaturated fatty acids is not well known.

Structure of palmitoleic acid (Source: Edgar181 via Wikimedia Commons)

Of this group, vaccenic acid and palmitoleic acid are the most common in nature. The latter is a non-essential fatty acid that can be found in a wide variety of fats of animal and vegetable origin, as well as those produced by marine organisms.

In humans, palmitoleic acid can be produced from the coenzyme A ester of its respective saturated fatty acid (palmitoyl-CoA) through reactions catalyzed by the enzyme desaturase, which belongs to the mono-oxygenase enzyme system present in the endoplasmic reticulum of hepatocytes and adipocytes.

This and other unsaturated fatty acids in cis configuration have important bodily functions, as they help to increase the fluidity of reserve triglycerides and phospholipid membranes that characterize all cellular organisms.

Furthermore, in mammals these fatty acids can serve as precursors for eicosanoids such as prostaglandins, prostacyclins, leukotrienes, etc.

Structure of palmitoleic acid

Structure of palmitoleic acid represented with 3D balls. Jynto and Ben Mills

Palmitoleic acid is a monounsaturated fatty acid, that is, it has lost a hydrogen atom and has two of its carbon atoms linked together through a double bond, also known as "unsaturation."

It is characterized by a length of 16 carbon atoms, which includes it in the list of long chain fatty acids. It has a molecular weight of 254,408 g / mol, a melting point of 3 ° C (making it liquid at room temperature), and a density of approximately 0.894 g / ml.

Since the position of its double bond is at carbon atom number 7 from the ω end of its carbon chain (the methyl group furthest from the carboxyl end), palmitoleic acid is said to belong to the family of omega fatty acids. 7, which are all monounsaturated.

Structure of palmitoleic acid (Source: Jü via Wikimedia Commons)

The chemical formula of this fatty acid is CH3 (CH2) 5CH = CH (CH2) 7COOH (C16H30O2) and the double bond at position 7 is in a cis configuration (one of the most common among natural unsaturated fatty acids), so This introduces a "fold" of about 30 ° in its molecular structure, which makes the molecule slightly unstable.

Although the trans configuration is less common, it can also be metabolized by animals and, synthetically speaking, the interconversion between the two forms can be achieved chemically, thermally or enzymatically.

Features

Cell membrane fluidity

As is true for most unsaturated fatty acids, palmitoleic acid is involved in the fluidity of cell membranes, since the angle of the double bond between its carbons 7 and 8 decreases the packing between the fatty acid chains of lipids.

Metabolism

Based on the results of experimental studies, palmitoleic acid is thought to have positive effects on cholesterol metabolism, hemostasis, and insulin sensitivity in humans.

Inhibition of apoptosis

It has also been proposed that it may participate in the inhibition of apoptosis induced by other fatty acids or by glucose in some pancreatic cells.

Other reports suggest that this fatty acid functions as a "fat derived lipid hormone" that stimulates the muscular action of insulin and suppresses hepatosteatosis (fatty liver) in fatty acid-binding protein-deficient experimental mice.

Decrease in blood pressure

Although it is not an essential fatty acid, it also seems to work to lower blood pressure, to combat "central obesity" (suppresses the accumulation and production of fat) and chronic inflammation, etc.

Satiating effect

A series of experiments conducted by Yang and colleagues in 2012 showed that palmitoleic acid has a "satiating" effect when administered with food for short periods of time in experimental rats.

The effect of palmitoleic acid on these animals reduces their food intake (especially when these results are compared with those obtained with other fatty acids used as "controls"), proving that it is due to an increase in the release of "satiety" hormones like cholecystokinin.

Negative effects

Despite these and many other apparent benefits of palmitoleic acid, some authors consider that it is a "double-edged sword" because, although it can be very effective against diseases as serious as cancer, usually natural sources and oils Rich in this omega 7 fatty acid they are also rich in palmitic acid.

Palmitic acid, unlike palmitoleic acid, is a fatty acid that forms thick or viscous solutions (palm oil is rich in palmitic acid), and its consumption is thought to increase the propensity for some diseases.

Likewise, palmitoleic acid has been shown to be an important product of endogenous lipogenesis and elevated levels of this acid in the plasma cholesterol of children with obesity have been identified as indices of adiposity and metabolic syndromes.

Where is this acid found?

Although palmitoleic acid is not found in large amounts in many food sources, the main natural sources of palmitoleic acid are plants and some marine organisms.

The oil from macadamia nuts (Macadamia integrifolia, where it represents 17% of total fat) or from the seeds of sea buckthorn (Hipophaë rhamnoides, of the Elaeagnaceae family and of the Rosales order) is rich in the cis isomer of palmitoleic acid Meanwhile, milk and its derivatives have the trans isomer.

This omega 7 fatty acid is also found in some blue-green algae and in the oil extracted from some marine species of fish and seals.

References

1. Araujo Nunes, E., & Rafacho, A. (2017). Implications of palmitoleic acid (palmitoleate) on glucose homeostasis, insulin resistance and diabetes. Current drug targets, 18 (6), 619-628.
2. Bruice, PY (2016). Essential organic chemistry.
3. Cunningham, E. (2015). What are n-7 fatty acids and are there health benefits associated with them? Journal of the Academy of Nutrition and Dietetics, 115 (2), 324.
4. Hernández, EM (2016). Specialty oils: functional and nutraceutical properties. In Functional Dietary Lipids (pp. 69-10.
5. Luckey, M. (2014). Membrane structural biology: with biochemical and biophysical foundations. Cambridge University Press.
6. Okada, T., Furuhashi, N., Kuromori, Y., Miyashita, M., Iwata, F., & Harada, K. (2005). Plasma palmitoleic acid content and obesity in children. The American journal of clinical nutrition, 82 (4), 747-750.
7. Yang, ZH, Takeo, J., & Katayama, M. (2013). Oral administration of omega-7 palmitoleic acid induces satiety and the release of appetite-related hormones in male rats. Appetite, 65, 1-7.