Muira Puama or Ptychopetalum is a genus of two species of flowering plants in the family Olacaceae (not to be confused with the Oleaceae or olive family), native to the Amazon rainforest. The indigenous name for the genus is Muira Puama, “potency wood”. The species are shrubs or small trees growing to about 14 feet in height. Its leaves are short-petioled, up to 3 inches in length and 2 inches in breadth light green on upper surface, dark brown on lower surface. The inflorescences consist of short axillary racemes of 4 to 6 flowers each. The root is strongly tough and fibrous, internally light brown with thin bark and broad wood, has a faint odor, and tastes slightly saline and acrid. “The Potency Wood”, Muira Puama, is a small tree that grows naturally in the Amazon River Basin. The bark, roots, and wood contain many complex structures, which have been used for energy, general health and blood flow in native cultures.
Historically all parts of Muira Puama have been used medicinally, but typically it is the bark and root of Ptychopetalum olacoides which is harvested and used both traditionally and in herbal products. It contains long-chain fatty acids, plant sterols, coumarin, lupeol, and the alkaloid muirapuamine. There is a second almost identical species, Ptychopetalum uncinatum, which is sometimes used as a substitute with the only noticeable difference being a lower concentration of the chemical lupeol.
The root and bark are used for a variety of ailments by indigenous peoples in the Rio Negro area of South America, but the effectiveness of Muira Puama preparations are unproven. There is evidence that Muira Puama is anxiogenic in rodents (causes anxiety), which would be consistent with a stimulant effect, without affecting coordination. However, rather than increasing the activity of excitatory neurotransmitters, it decreases the activity of an inhibitory neurotransmitter, GABAA.