In vitro studies on the intestinal absorption of curcumin in rats.

When everted sacs of rat intestines were incubated with 50--750 ~g of
curcumin in 10 ml incubation medium, 30--80% of the added curcumin
disappeared from the mucosal side. No curcumin was however detectable
in the serosal fluid. Less than 3% of the added curcumin was found in the
tissue at the highest concentration. In experiments with [aH]curcumin,
5--6% of added radioactivity was found in the serosal side. TLC examination
of the mucosal extract showed the presence of 2 compounds, 1 corresponding
to curcumin and the other to a less polar, colourless compound. The serosal
fluid had no curcumin but a compound whose RF was identical with the
colourless compound present in the mucosal side. These experiments indicated
that curcumin undergoes transformation during absorption from the
intestine.