Psychedelic experience sources of some psychedelic drugs such as ayahuasca and mescaline-containing cacti are sometimes referred to as "plant teachers". Similarly, in a follow-up to the psilocybin and mysticism study at Johns Hopkins, researchers observed that psilocybin: "occasions personally and spiritually significant mystical experiences that predict long-term changes in behaviors, attitudes and values". Psychedelic experience includes the full range of mystical or religious experiential phenomena. Two scientific studies have concluded that psilocybin (a typical psychedelic compound that occurs naturally in psilocybin mushrooms) reliably triggers mystical-type experiences. The more recent study at Johns Hopkins University identified mystical experiences by means of several questionnaires
Mescaline at the two meta positions with respect to the alkyl substituent, experiences a final methylation at the 4 carbon by a guaiacol-O-methyltransferase, which also operates by a SAM-dependent mechanism. This final methylation step results in the production of mescaline. Phenylalanine serves as a precursor by first being converted to -tyrosine by L-amino acid hydroxylase. Once converted, it follows the same pathway as described above. Mescaline was first synthesized in 1919 by Ernst Späth from 3,4,5-trimethoxybenzoyl chloride. Subsequent to this, numerous approaches utilizing different starting materials have been developed. Notable examples include the following: Tolerance builds with repeated usage, lasting for