Isn't DMT the main active ingredient in ayahuasca (the other being an MAOI that prevents the DMT from being metabolized in the gut)?
Correct—but the formulation in ayahuasca has radically different effects than pure DMT.
Pure DMT gives a very short trip (a few minutes) while Ayahuasca trips can last for hours and hours.
Btw—McKenna believed (and I agree) that a deep study of these drugs will yield incredible information about human consciousness—not just a materialistic discussion of chemical reactions in the brain—but a new understand of what human consciousness is and how it really works.
He was convinced the human brain (under DMT and psilocybin, but not Ayahuasca or LSD) could tap into “another dimension” or “the logos”, something “out there” beyond the reach of scientific measurement at this time.