Ayahuasca is used largely as a religious sacrament. Those
whose usage of ayahuasca is performed in non-traditional
contexts often align themselves with the
philosophies and cosmologies associated with ayahuasca
shamanism, as practiced among indigenous peoples like the
Urarina of Peruvian Amazonia. The religion Santo Daime
uses it. While non-native users know of the spiritual
applications of ayahuasca, a less well-known
traditional usage focuses on the medicinal
properties of ayahuasca. Its purgative properties are highly
important (many refer to it as la purga, "the purge").
Harmine compounds are of beta-carboline origin. The three
most studied beta-carboline compounds found in the B.
caapi vine are harmine, harmaline and tetrahydroharmine.
Harmine and harmaline are selective and
reversible inhibitors of MAO-A, while tetrahydroharmine is a
weak serotonin uptake inhibitor. This inhibition of MAO-A
allows DMT to diffuse un-metabolized past the membranes
in the stomach and small intestine and eventually get through
the blood-brain barrier to activate receptor sites in the
brain. Without the MAOI of MAO-A, DMT would be
metabolized in the digestive tract and would not have an
effect when taken orally.