Graviola has a long history of use among indigenous and herbalists in South America.
Generally, all parts of graviola tree are employed (including the bark, leaves, roots, fruit, and fruit seeds), each one for different purposes.
Usually the fruit and fruit juice are taken for worms and parasites, to cool fevers, to increase mother's milk after childbirth, and as an astringent for diarrhea and dysentery. The crushed seeds are used against internal and external parasites, head lice, and worms. The bark, leaves, and roots are considered sedative, antispasmodic, hypotensive, and nervine.
However, Graviola has become renowned after an 1976 plant screening program by the National Cancer Institute (U.S.), which showed how graviola leaves and stems might be toxic against several cancer cell lines (such as lung, breast, pancreatic carcinoma, colon, liver, ovaraian, cervical, skin, bladder, lymphoma, etc.), including multi-drug resistant ones.
Most of the research on graviola has focused on phytochemicals called Annonaceous acetogenins.Three separate research groups have reported that acetogenins might inhibit enzyme process that are only found in the membranes of cancerous tumor cells, thus acetogenins are toxic to abnormal cells but have no toxicity to healthy cells.
Purdue University (U.S.) has conducted several studies on the acetogenins, much of which has been funded by The National Cancer Institute and/or the National Institute of Health (NIH).
Acetogenins can be found in graviola's leaf and stem, bark, and fruit seeds.
However, different alkaloid chemicals in the seeds and roots have shown some neurotoxic effects when consumed chronically.
An abnormally high rate of atypical parkinsonism has been found in islands such as Guam (Northern Mariana Islands), New Caledonia, Western New Guinea, Kii penisula in Japan and French West Indian Island of Guadalupe in the Caribbean. Thus, epidemiological evidence suggests a close association of the disease with regular consumption of soursop fruit.
Therefore, using the seeds and root of graviola in high amounts or for a long period of time is not recommended until further research is performed.
L. Taylor, The Healing Power of Rainforest Herbs