SOURSOP Graviola is found in the tropics. The seeds are toxic. On the Caribbean island of Guadeloupe, within the French West Indies, there is a rare form of Parkinson's disease that is seen with an unusually high frequency among those who eat soursop. This atypical Parkinson's does not respond well to medical treatment. The alkaloids extracted from graviola may cause neuronal dysfunction and degeneration leading to symptoms of Parkinson's disease. Research is developing soursop as a cancer remedy. It can treat cancer by destroying the cancer cells, without any side effects such as nausea, vomiting, hair loss and weight loss.