Several alkaloids that function as monoamine oxidase inhibitors (MAOIs) are found in the seeds of Peganum harmala (also known as Harmal or Syrian Rue), as well as tobacco leaves including harmine, harmaline, and harmalol, which are members of a group of substances with a similar chemical structure collectively known as harmala alkaloids. These alkaloids are of interest for their use in Amazonian shamanism, where they are derived from other plants. The harmala alkaloid harmine, once known as telepathine and banisterine, is a naturally occurring beta-carboline alkaloid that is structurally related to harmaline, and also found in the vine Banisteriopsis caapi. Tetrahydroharmine is also found in B. caapi and P. harmala. Dr. Alexander Shulgin has suggested that harmine may be a breakdown product of harmaline. Harmine and harmaline are both a reversible inhibitor of monoamine oxidase A (RIMAs). They can stimulate the central nervous system by inhibiting the metabolism of monoamine compounds such as serotonin and norepinephrine. The harmala alkaloids occur in Peganum harmala in concentrations of roughly 3%, though tests have documented anywhere from 2-7% or even higher, as natural sources tend to vary widely in chemical makeup. Harmala alkaloids are also found in the Banisteriopsis caapi vine, the key plant ingredient in the sacramental beverage ayahuasca, in concentrations that range between 0.31 and 8.43% for harmine, 0.03-0.83% for harmaline and 0.05-2.94% for tetrahydroharmine. Although other psychoactive plants are occasionally added to ayahuasca to achieve visionary states of consciousness, the recipes vary greatly and no single combination is common. Peganum harmala, normally consumed as a tea or used as an incense, is mentioned in classical Persian literature both as a sacred sacrament and as a medicine. The harmala alkaloids are not especially psychedelic, even at higher dosages, when hypnagogic visions, alongside vomiting and diarrhea, become the main effect. Harmala alkaloids are also found in many other plants, such as Passiflora. The leaves of P. incarnata have been reported variously to give 0.005%, 0.12 mg%, and 0% harmala alkaloids. Telepathine Telepathine was originally thought to be the active chemical constituent of Banisteriopsis caapi, a key plant ingredient in the preparation of ayahuasca; a sacramental beverage from the Amazon. This isolated chemical was so named because of the reported effects of ayahuasca among the indigenous users, including: collective contact with and/or visions of jaguars, snakes, and jeweled birds, and ancestral spirits; the ability to see future events; and as the name suggests,