Annona montana, mountain soursop or wild custard apple, is a tropical fruit tree in the Annonaceae family. Related species include cherimoya (A. cherimola) and soursop (A. muricata); paw paw (Asimina triloba) is also in the family. Mountain soursop is native to Central America, the Amazon, and islands in the Caribbean. In its native range, it grows at altitudes from sea level to 650 metres (2,130 ft, Wikipedia 2011). It is occasionally cultivated, and is adaptable to a wide range of soil types and is hardier than many other tropical fruit trees, capable of tolerating temperatures below freezing for brief periods.
The trees, which are evergreen, grow to 10 m (33 feet) tall, with a spreading crown and very glossy leaves. Mountain soursop trees bear fruit more or less continuously starting two to three years after planting. Fruits are about 15 cm (5.9 inches) long, nearly round, with dark green skin covered with dense soft prickles and dark brown hairs (FOC 2011). Fruits have a yellow, fibrous flesh that is aromatic, sour to bitter, and contains many light-brown, plump seeds. Fruits are considered inferior to the soursop (Popenoe 1920), so although it is occasionally cultivated, commercial production is not frequent.
Mountain soursop, which along with soursop is also known as graviola, has numerous traditional medicinal uses in South American and the Caribbean. Fruit, seeds, bark, leaves, and roots have all been used to treat intestinal parasites, coughs (including asthma and bronchitis), inflammation, diabetes, and hypertension, among many uses (Taylor 2005). Research on extracts of graviola have documented antiviral, antiparasitic, antirheumatic, anti-inflammatory, and antihyperglycemic properties; it has also been used as an anti-depressant and at least one study has found it effective against multi-drug resistant cancer cells (Sloan-Kettering 2011, Oberlies et al. 1997). Acetogenins are the alkaloid compounds thought to be responsible for these effects, although other components, including quinolones, annopentocins, and annomuricins may also be involved.
In addition to the health benefits, mountain soursop (along with other members of the Annonaceae family) also contains small amounts of neurotoxic alkaloids, such as annonacin, which appear to be linked to atypical Parkinsonism and other neurological effects if consumed frequently or in large quantities (Sloan-Kettering 2011Champy et al. 2005, Caparros-Lefebvre and Elbaz 1999).
Graviola has become popular as a nutritional medicinal supplement and is sold in health food stores and online. Data on quantities harvested and sold commercially are difficult to find. At least one supplier claims that materials are harvested in the wild in Amazon rainforests (Raintree 2011).