The San Pedro cactus (Echinopsis pachanoi, syn. Trichocereus pachanoi) is a fast-growing columnar cactus native to the Andes Mountains of Peru between 2000–3000 m in altitude. It is also found in Argentina, Bolivia, Chile and Ecuador, and it is cultivated in other parts of the world. Uses for it include traditional medicine and traditional veterinary medicine, and it is widely grown as an ornamental cactus. It has been used for healing and religious divination in the Andes Mountains region for over 3000 years. It is sometimes confused with its close relative, Echinopsis peruviana (Peruvian Torch Cactus).
The plant is light to dark green, sometimes glaucous, and has 4–9 (usually 5–7) ribs. Groups of 1–4 small, yellow to light brown spines are located at nodes which are spaced evenly, approximately 2 cm apart, along the ribs. Echinopsis pachanoi can grow up to 5 metres (16 ft) tall and have multiple branches, usually extending from the base. The tallest recorded specimen was 12.2 metres (40 ft) tall. The cactus blossoms at night with flowers up to 20 centimetres (8 in) in diameter, and rarely it bears red, tasty fruit.
Hordenine, the alkaloid in Echinopsis pachanoi which gives it the ability to inhibit 18 different kinds of Penicillin resistant bacteria.
Echinopsis pachanoi, San Pedro Cactus, the tall cactus in the background, in its natural habitat in Peru
Echinopsis pachanoi has a long history of being used in Andean traditional medicine. Archeological studies have found evidence of use going back two thousand years, to Moche culture. Currently it is widely known and used to treat nervous conditions, joint problems, drug addictions, cardiac disease, and high blood pressure, and it has unique antimicrobial properties.
Echinopsis pachanoi contains hordenine and “. . .it has been shown that hordenine, N,N-Dimethyl-hydroxyphenylethylamine, exhibits an inhibitory action against at least 18 strains of penicillin resistant Staphylococcus bacteria.”
San Pedro contains a number of alkaloids, including the well-studied chemical mescaline (0.21 – 1.8%), and also 3,4-dimethoxyphenethylamine, 4-hydroxy-3-methoxyphenethylamine, 3-hydroxy-4,5-dimethoxyphenethylamine, 4-hydroxy-3,5-dimethoxyphenethylamine, anhalonidine, anhalinine, hordenine, tyramine, and 3-methoxytyramine.
Mescaline (3,4,5-trimethoxyphenethylamine) is a psychedelic drug and entheogen, which is also found in some other species of genus Echinopsis (i.e. Echinopsis lageniformis, Echinopsis peruviana, and Echinopsis scopulicola) and the species Lophophora williamsii (peyote).
Anecdotal evidence suggests that the highest concentrations of active substances are found in the layer of green photosynthetic tissue just beneath the skin.
There are various mescaline extraction techniques, simple (boiling in water 5 to 7 hours) and complex (such as an acid-base extraction), the latter technique yielding a material with a significantly higher concentration of mescaline.