Caffeine, or coffee? They are very different substances: one is a pure alkaloid with well-defined effects, the other is a concoction of hundreds, possibly thousands of active ingredients.

Most relevantly, coffee contains a relatively large amount of Harmala alkaloids, which are a family of beta-carboline monoamine oxidase inhibitors commonly found in Ayahuasca brews (and named after one of its ingredients, Penganum harmala).