Biology Reference
In-Depth Information
more abundant than previously estimated. New HPLC technologies
applied to the analysis of ETs and their metabolites in food and
biological fluids has led to an increase in the understanding their
stability, metabolism (both microbial and mammal cells metabolism)
bioavailability and tissue distribution. It has been observed that EA and
ETs can disappear when in contact with animal cells or tissues, and this
has been attributed to irreversible linkage of these compounds with
proteins or other cell structures. For example, intestinal cells become
yellow pigmented after incubation with punicalagin, and the colour does
not disappear even after extraction with strong organic solvents such as
methanol. This agrees with results observed with EA, in which very
strong conditions are necessary to remove the EA-protein linkages in
animal model intestinal tissues (Whitley
et al.
, 2003). More research is
needed to further understand the interactions of ETs and EA with
proteins and other cell components in order to understand the fate of
these polyphenols
in vivo
.
7.5 Models to Study Bioavailability and Metabolism
In order to understand the metabolism and bioavailability of ETs,
different experimental approaches can be used. These include: i)
in vitro
simulation of gastrointestinal (GI) digestion, which may be useful to
evaluate the ETs stability and bioaccesibility; ii)
in vitro
studies with
human GI tract cell lines to evaluate uptake and metabolism in the GI
cells before passing to blood circulation; iii)
in vivo
studies with animal
models (from mice and rats to pigs) that are essential for toxicological
studies, as well as confirming bioavailability and metabolism in
mammals and evaluating tissue distribution; iv) clinical interventions
with human volunteers to determine human bioavailability and
metabolism using the knowledge generated in animal studies and to
confirm the relevant metabolites, as well as their
in vivo
concentrations
in humans.
