Practitioners of herbal medicine recommend the fruit and leaves of the graviola tree to relieve stomach distress, fever, pain and respiratory problems such as cough and asthma, and for many other medical problems. Soursop contains a number of natural substances that have biological activity, according to Memorial Sloan-Kettering Cancer Center. These include fatty compounds called acetogenins, especially one called annonacin, along with other compounds called quinolones, annopentocins and two alkaloids, coreximine and reticuline. Soursop's acetogenins are the compounds that have been most studied, especially for their potential to prevent or slow the growth of cancer. The Cancer Center also says that some compounds in soursop may be naturally antiviral and antiparasitic, and may also suppress inflammation.