Mangosteen (Garcinia mangostana) is an exotic, tropical fruit with a slightly sweet and sour flavor.It's originally from Southeast Asia but can be found in various tropical regions around the world.The fruit is sometimes referred to as purple mangosteen because of the deep purple color its rind develops when ripe. In contrast, the juicy inner flesh is bright white. Though mangosteen is a relatively obscure fruit, it shouldn't be overlooked, as it may offer many health benefits due to its rich supply of nutrients, fiber, and unique antioxidants.