The Graviola is an evergreen tree, found in the rain forests of Africa, South America, and Southeast Asia. Its scientific name is Annona muricata. It is also known as custard apple, cherimoya, guanabana, soursop and brazilian paw paw. The active ingredient is thought to be a type of plant compound (phytochemical) called annonaceous acetogenins. 

Caution: Graviola slows down the heart and lowers the blood pressure. Large doses may cause nausea and vomiting. Do not use in pregnancy or lactation, or in the presence of liver, or kidney disease. Do not take in combination with Coenzyme Q10 supplements.  Contraindications: Graviola has demonstrated uterine stimulant activity in an animal study (rats) and should therefore not be used during pregnancy.