Ellagitannins in pomegranate juice

Since ancient times, pomegranate has been known for its medicinal properties. Most of those beneficial effects have been attributed to the pomegranate metabolites such as polyphenols, with a particular focus on hydrolysable tannins. The health benefits of pomegranate have been mainly related to its ellagitannins and ellagic acid content.

Ellagitannins belong to the chemical class of hydrolyzable tannins, which release ellagic acid on hydrolysis. In addition, pomegranate juice contains other polyphenols, such as anthocyanins that are present in the fruit arils and impart its brilliant red-purple color.

Ellagitannins are bioactive polyphenols present in pomegranate. Pomegranate juice obtained by squeezing the whole fruit has the highest concentration of ellagitannins than any commonly consumed juice and contains the unique ellagitannin, punicalagin.

In the commercial pomegranate juice industry, these ellagitannins are extracted from the husk in significant quantities into the juice due to their hydrophilic properties.

Ellagitannin is a hydrolyzable polymer contrary to the rest of the family of tannins and can be hydrolyzed to more simple monomers that can be eventually metabolized and that can become bioavailable with subsequent exposition of the body to these metabolites. More than 60 hydrolysable tannins have been found in the fruit peel, arils and membranous walls.

The main ellagitannins identified in foods (specially in fruits, nuts, and seeds) are punicalagin, sanguiin H6, lambertianin C, pedunculagin, vescalagin, castalagin, casuarictin and potentillin (seeds). In particular, punicalagin is the predominant form of the hydrolysable tannins present in pomegranate and is responsible for more than 90% of antioxidant bioactivity contained in pomegranate juice.
Ellagitannins in pomegranate juice

Tea and Cancer

Tea and Cancer
Most of the on cancer chemoprevention by tea has been conducted using green tea or its individual polyphenolic constituents.

Less work has been reported on black tea.

In animal studies, the polyphenolic fraction isolated from green tea. The water extract of green tea, or individual polyphenolic antioxidants present in green tea have afforded protection against chemically induced carcinogenesis in the lung, liver, esophagus, forestomach, duodenum, pancreas, colon, and breast.

The raises possibility that green tea consumption and its associated catechins may lower cancer risk in humans.

Studies have shown that green tea intake increases the excretion of a class of carcinogens known as heterocyclic arylamines formed during the cooking of meat, poultry and fish; this is expected to reduce DNA adduct formation, in particular and carcinogenesis, in general.

Consumption of both green and black tea aqueous extracts influences the excretion of mutagens and promutagens in the urine of animals.

Several epidemiological studies suggest that tea and its associated compounds may prevent some, but not all, cancers.

This is understandable, because cancer is a complex disease with multiple etiologies, even for one body site.

It is, therefore a false hope that any nutritional or synthetic agent can prevent or treat all cancer types.

However, based on a large volume of cell culture, animal studies and human observational studies, there is hope that green tea consumption can retard cancer development at selected sites in some populations.

The challenge is to elucidate what cancer type can be prevented by tea. This requires extensive research for which considerable resources are required.
Tea and Cancer