- 1Medical University of Warsaw - Department of Pharmacognosy and Molecular Basis of Phytotherapy Warsaw, Poland.
Abstract
The
popularity of food products and medicinal plant materials containing
hydrolysable tannins (HT) is nowadays rapidly increasing. Among various
health effects attributable to the products of plant origin rich in
gallotannins and/or ellagitannins the most often underlined is the
beneficial influence on diseases possessing inflammatory background.
Results of clinical, interventional and animal in vivo studies clearly
indicate the anti-inflammatory potential of HT-containing products, as
well as pure ellagitannins and gallotannins. In recent years a great
emphasis has been put on the consideration of metabolism and
bioavailability of natural products during examination of their
biological effects. Conducted in vivo and in vitro studies of
polyphenols metabolism put a new light on this issue and indicate the
gut microbiota to play a crucial role in the health effects following
their oral administration. The aim of the review is to summarize the
knowledge about HT-containing products' phytochemistry and their
anti-inflammatory effects together with discussion of the data about
observed biological activities with regards to the current concepts on
the HTs' bioavailability and metabolism. Orally administered
HT-containing products due to the limited bioavailability of
ellagitannins and gallotannins can influence immune response at the
level of gastrointestinal tract as well as express modulating effects on
the gut microbiota composition. However, due to the chemical changes
being a result of their transit through gastrointestinal tract,
comprising of hydrolysis and gut microbiota metabolism, the activity of
produced metabolites has to be taken into consideration. Studies
regarding biological effects of the HTs' metabolites, in particular
urolithins, indicate their strong and structure-dependent
anti-inflammatory activities, being observed at the concentrations,
which fit the range of their established bioavailability. The impact of
HTs on inflammatory processes has been well established on various in
vivo and in vitro models, while influence of microbiota metabolites on
silencing the immune response gives a new perspective on understanding
anti-inflammatory effects attributed to HT containing products,
especially their postulated effectiveness in inflammatory bowel diseases
(IBD) and cardiovascular diseases.
