Picralima is a plant genus in the family Apocynaceae., first described as a genus in 1896. It contains only one known species, Picralima nitida, native to tropical Africa (Benin, Ghana, Ivory Coast, Nigeria, Gabon, Cameroon, Cabinda, Central African Republic, Republic of Congo, Zaire, Uganda).
Picralima nitida, the akuamma, is a tree. The dried seeds from this plant are used in traditional medicine throughout West Africa, particularly in Ghana as well as in the Ivory Coast and Nigeria. The seeds are crushed or powdered and taken orally, and are mainly used for the treatment of malaria and diarrhoea, and as a painkiller. The plant produces the alkaloids pericine and akuammine, among others.
An enterprising Ghanaian hospital started manufacturing standardized 250 mg capsules of the powdered P. nitida seed, and sold them around the country where they became used pain relief product. This then led researchers to try to discover the active component of the seeds.
P. nitida seeds contain a mixture of alkaloids producing antipyretic and antiinflammatory effects along with analgesia in animal studies. Several of these were shown to bind to opioid receptors with weak affinity in vitro, and two compounds, akuammidine and ψ-akuammigine, were found to be μ-opioid agonists, although not particularly selective.