Ellagitannins: Pomegranate Health Benefits

The pomegranate, renowned for its medicinal attributes since ancient times, receives significant acclaim for its beneficial compounds, particularly polyphenols, with a specific focus on hydrolysable tannins. The health advantages associated with pomegranates are predominantly linked to their ellagitannins and ellagic acid content.

Ellagitannins, falling within the category of hydrolyzable tannins, release ellagic acid when hydrolyzed. Furthermore, pomegranate juice contains additional polyphenols, including anthocyanins found in the fruit arils, contributing to its vibrant red-purple hue.

Ellagitannins, identified as bioactive polyphenols in pomegranates, exhibit the highest concentration in juice obtained by pressing the entire fruit, notably featuring the distinctive ellagitannin, punicalagin.

In the commercial pomegranate juice industry, the hydrophilic properties of ellagitannins facilitate their substantial extraction from the husk into the juice.

Ellagitannin, set apart from other tannin varieties, is a hydrolyzable polymer that can break down into simpler monomers. These monomers can undergo metabolism, becoming bioavailable when the body is subsequently exposed to these metabolites. Over 60 hydrolysable tannins have been identified in the pomegranate peel, arils, and membranous walls.

Prominent ellagitannins found in various foods, especially in fruits, nuts, and seeds, include punicalagin, sanguiin H6, lambertianin C, pedunculagin, vescalagin, castalagin, casuarictin, and potentillin (seeds). Specifically, punicalagin represents the primary form of hydrolysable tannins in pomegranates, responsible for over 90% of the antioxidant bioactivity present in pomegranate juice.
Ellagitannins: Pomegranate Health Benefits

Apple juice rich with polyphenol

Apples and apple juices are traditionally regarded as health foods all over the world. The marked antioxidant ability of phenolics from apples against free radicals is thought to account for the positive effects of apple and apple juices on human health.

Among the most important constituents of apple juice are phenolic compounds, such as: hydroxycinnamic acids, dihydrochalcones, flavonols (quercetin glycosides), catechins and oligomeric procyanidins.

Apples have the highest proportion of free polyphenols compared to other fruits. Polyphenols are usually divided into several different groups (simple phenols, benzoic acids, phenyl propanoids, and flavonoids) on the basis of the number of carbon atoms in conjunction with the structure of the basic phenolic skeleton.

The polyphenols content in apples can range widely from 10 mg to 500 mg/ 100g of raw material. The amount of polyphenols in juices is much smaller. This is mainly due to clarification processes or thermal juice preservation (pasteurization).

The concentration of polyphenols is influenced by the plant variety as well as environmental factors, including geographic region, growing season, and storage.

Apples without skin contain less than half the amount of quercetin, the most abundant apple flavonoid, harbored by whole apples.

Quercetin is a member of the class of flavonoids called flavonoles and forms the backbone for many other flavonoids including the citrus flavonoids like rutin, hesperidins, Naringenin and tangeritin.

Quercetin is a flavonoid derived from flavone, a natural polyphenolic antioxidant. Quercetin occurs in nature as easily hydrolysable glycoside (quercetin3-galactoside, quercetin-3-glucoside, and quercetin3-rhamnoside).
Apple juice rich with polyphenol

Bioactive compound of blueberry

Blueberries belong to the genus Vaccinium, which includes more than 450 plants grown in all parts of the world. Members of the Vaccinium genus possessing the darkest-colored fruits appear to provide the greatest health benefits, a fact that scientists attribute to the compounds that give the plants their dark pigmentation.

Generally, blueberries in a fresh form consist of water (84%), carbohydrates (9.7%), proteins (0.6%) and fat (0.4%). The average energetic value of a 100-g serving of fresh blueberries is estimated at 192 kJ. Blueberries are also a good source of dietary fiber that constitutes 3%–3.5% of fruit weight.

Epidemiological studies have shown evidence that the consumption of these fruits is linked to the prevention of chronic non-transmissible diseases, mainly due to the presence of bioactive phytochemical compounds such as phenolic acids, flavonoids and carotenoids.

The total content of polyphenols in blueberries ranges from 48 up to 304 mg/100 g of fresh fruit weight (up to 0.3%) and strictly depends on the cultivar, growing conditions and maturity, and its estimation may vary depending on the analytical procedure used.

Polyphenols present in blueberries include, i.e., flavonoids, procyanidins (monomeric and oligomeric form), flavonols (i.e., kaempferol, quercetin, myricetin) phenolic acids (mainly hydroxycinnamic acids) and derivatives of stilbenes.

Phenolic compounds in the blueberry can be classified into two major groups: non-flavonoids and flavonoids. Flavonoids with a 15-carbon skeleton arranged in a common basic chemical structure, with two aromatic rings linked by a chain of three carbons, form a C6-C3-C6 system.

Non flavonoids, phenolic or simple acids ,are characterized by having a benzene ring, a carboxylic acid grouping ,and one or more hydroxyl groups and / or methoxyl in the molecule.
Bioactive compound of blueberry

Polyphenol in pomegranate juice

Edible parts of pomegranate fruits (about 50% o total fruit weight) comprise 80% juice and 20% seeds. Fresh juice contains 85% moisture, 10% total sugars, 1.5% pectin, ascorbic acid, polyphenols and flavonoids.

Polyphenols are relevant constituents regarding the organoleptic properties of pomegranate arils and juice as they are responsible for the distinctive red pigmentation and provide mild astringency that is characteristics of pomegranate flavor.

The most important product derived from the pomegranate is its juice. The juice obtained from these arils contains anthocyanins (delphinidin, cyanidin, and pelargonidin 3-glucosides and 3.5 glucosides), ellargic acid glycosides (ellagic acid glucoside, arabinoside and rhamnoside), free ellagic acid, ellagitannins (several punicalagin, isomers, punicalin and some punicalagin polymeric forms) and gallotannins.

Study shows that pomegranate polyphenols protected low-density lipoprotein against cell-mediated oxidation via two pathways, including either direct interaction of the polyphenols with the lipoproteins and/or an indirect effect through accumulation of polyphenols in arterial macrophages.
Polyphenol in pomegranate juice