The ellagic acid is a tetracyclic organic compound whose chemical formula is C14H6OR8. It is a polyphenol, being the dimer of gallic acid. It is also known as benzoaric acid. It is a yellow or cream colored crystalline solid, very stable against temperature. It is a weak acid very slightly soluble in water but soluble in basic or alkaline medium..
It is found distributed in the vegetable kingdom contained in various fruits, such as pomegranate, grapes, nuts and in drinks such as wine and tea. It is abundant in wood and woody debris.
It has several important biological properties: antioxidant, anti-inflammatory, anticancer, antimutagenic, protects the liver and reduces the level of fats in the blood plasma. It exerts a protective effect on neurons and favors the generation of insulin.
It acts synergistically with other natural polyphenols. For this reason, the whole pomegranate fruit is much more effective as an antioxidant and anticancer than ellagic acid alone..
Although it is not easily absorbed by the human intestine, its derivative compounds or metabolites are, also performing its antioxidant properties.
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Ellagic acid has four cyclic structures fused together. It also has four phenolic -OH groups and two lactone-like structures.
- Ellagic acid.
- Benzoaric acid.
- 4,4 ', 5,5', 6,6'-hexahydroxydiphenic acid-2,6,2 ', 6'-dilactone.
Cream or yellow solid that crystallizes in the shape of needles.
302.19 g / mol.
Greater than 360 ºC (it is highly thermostable).
1,667 g / cm3 at 18 ºC.
Weakly soluble in water: less than 1 mg / mL at 21 ºC. Less than 10 mg / mL at pH 7.4. Weakly soluble in ethyl alcohol.
Soluble in alkaline medium and in pyridine. Practically insoluble in ethyl ether.
It has four phenolic -OH groups. Here is the tendency to dissociate from each of these:
pKa1 = 6.69; pKa2 = 7.45; pKa3 = 9.61; pKa4 = 11.50.
It is a weak acid, which ionizes at a physiological pH.
It has four rings that represent the lipophilic or hydrophobic part of the molecule. It has four phenolic groups and two lactone groups that are the hydrophilic or water-related part.
Certain researchers carried out in the laboratory the synthesis of ellagic acid starting from methyl gallate by oxidative coupling, through the formation of α-pentagaloylglucose..
Ellagic acid is a very common compound in plants. It is very abundant in fruits such as pomegranate, berries, strawberries, raspberries, blackberries, grapes, persimmon, peach, plum, walnuts, almonds and in drinks such as wine and tea.
In grapes it is more abundant in the skin of the fruit than in the pulp, and it is more abundant in the pulp than in the juice. The more the grape ripens, the higher the ellagic acid content.
It can be found in its free form or more commonly in conjugated form with glycosides (such as xylose and glucose) or as part of ellagitannins (polymeric molecules).
The various varieties of tea are a significant source of ellagic acid in the form of ellagitannins..
Ellagitanins are bioactive polyphenols that are not absorbed intact by the human intestine, but can be hydrolyzed to ellagic acid by the gastrointestinal flora of the colon..
All woods contain ellagic acid, which is one of the causes of the antioxidant effect of spirits aged or aged in wooden barrels. It is abundantly present in whiskey.
Woody debris such as sawdust or wood chips are rich natural sources of ellagic acid.
It is considered a compound with several biological activities: anticancer, antioxidant, antimutagenic, anti-inflammatory and cardioprotective.
It inhibits the growth of microorganisms, as it sequesters metal ions that are critical for the metabolism and growth of microbes. Acts as a free radical scavenger and antiviral.
It is believed that it could have potential in the prevention of certain chronic diseases. In addition, it inhibits wrinkles caused by UV rays.
It is such a good antioxidant that during plastic surgery small amounts of ellagic acid are applied to the skin to prevent necrosis..
It is a stimulator of immune functions and its joint administration has been proposed in chemotherapy of patients with prostate cancer..
It has antiproliferative activity against skin, esophageal and colon cancer, slows down the cell cycle and induces apoptosis of malignant cells. Acts in various DNA maintenance reactions preventing genome instability that otherwise leads to cancer.
It is antihepatotoxic, antisteatotic, anticolestatic, antifibrogenic, antihepatocarcinogenic and antiviral.
Hepatotoxicity refers to liver dysfunction or damage associated with exposure to drugs or substances foreign to the body. Steatosis is fatty liver disease. Cholestasis is the interruption of the flow of bile into the duodenum. Liver fibrosis is an exaggerated repair of tissues subject to chronic damage.
Ellagic acid inhibits alcohol-induced liver cell damage by increasing antioxidant levels, eliminating free radicals and stabilizing cell membranes..
Reduces the level of lipids in the circulation, preventing their peroxidation. Reduces plasma cholesterol. Inhibits protease activity in liver pathogenic viruses, preventing their proliferation.
It exerts a neuroprotective effect by improving the symptoms of Alzheimer's disease caused by the accumulation in the brain of advanced glycation end products, which is the reaction between sugars and proteins that leads to the aging of cells.
It acts on the β cells of the pancreas, stimulating insulin secretion and reducing glucose intolerance.
Ellagic acid has an antiproliferation effect on cancer cells in gallbladder cancer. Inhibits tumor invasion and chemotaxis, which is the reaction of cells against chemicals.
Significantly reduces tumor growth rate, infiltrating behavior, and tumor-associated angiogenesis or blood vessel formation.
Therefore, it is considered to have potential as an adjunct therapy in the treatment of gallbladder cancer..
Ellagic acid acts synergistically with certain flavonoids such as quercetin, present in fruits and vegetables, to inhibit cell growth and promote apoptosis in leukemia cells.
Synergy is a phenomenon that in this case means that the effect produced by several chemical compounds together is greater than the result of the individual sum.
This effect increases even more in the presence of resveratrol, another polyphenol present in many plants, fruits and vegetables..
Ellagic acid is one of the most powerful phytochemicals found in the pomegranate fruit, but certain studies indicate that it is not as strong as the pomegranate itself, since in the whole fruit there are a series of chemical compounds that act synergistically. with ellagic acid as anticancer and antioxidant.
Certain researchers have found that ellagic acid protects cells from some mechanisms that lead to their degeneration.
Eliminates NO radicalsx (which are involved in the generation of Parkinson's), decreases the mechanism of formation of reactive oxygen species and reactive nitrogen species and imparts antiapoptosis properties.
It thus exerts a neuroprotective effect. It can also bind to human serum albumin.
These results indicate that ellagic acid can provide support in overcoming Parkinson's through a prophylactic or disease prevention approach..
Ellagic acid present in matured whiskey has been experimentally determined to prevent alcohol-induced gastritis. Exerts a gastroprotective effect against gastric lesions.
In addition, a study showed that it protects the body from alcohol toxicity, by reducing certain enzymes and increasing the antioxidant mechanism.
Its effect appears to be multifactorial in the healing of gastric ulcers. This makes it a good candidate for developing a multipurpose anti-ulcer drug..
Although ellagic acid exhibits good antioxidant activity, it has solubility problems in aqueous medium and therefore has low bioavailability when administered orally..
It is very poorly absorbed and is rapidly eliminated from the body, which limits its potential as an antioxidant due to its inability to reach adequate concentrations in tissues..
Its low bioavailability is attributed to several factors: (1) its low solubility in water, (2) it is metabolized by microorganisms in the gastrointestinal tract, (3) it is rapidly eliminated from the body due to its short half-life in plasma, ( 4) irreversibly binds to cellular DNA and proteins.
However, it has been found that supplying it in the form of a complex with phospholipids increases its bioavailability and antioxidant activity. Phospholipid complex has better nutritional efficacy for a longer period of time than ellagic acid alone.
After the consumption of foods rich in ellagitannins, in the gastrointestinal tract these are hydrolyzed to ellagic acid by the bacteria that produce the enzyme tannase..
The lactone rings of ellagic acid open, then decarboxylation and then dehydroxylation occurs through enzymatic reactions and various urolithins are formed by certain bacteria in the colon. Finally urolithin A and B are obtained.
These metabolites are absorbed by the intestine and reach the blood plasma.
These urolithins are believed to have anti-estrogenic, anti-aging, and anti-inflammatory biological effects. They have also been found to have an effect against melanoma or skin cancer, as they inhibit the formation of melanin and inhibit the activity of enzymes that promote melanoma..
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