The two main flavonoids found in the mangosteen are catechins (found in green tea) and proanthcyandins (found in grape seeds). Many research institutions, such as The Mayo Clinic, The Linus Pauling Institute, UCLA Center for Human Nutrition and many others have studied flavonoids extensively.While science is still progressing in its attempt to validate the uses of mangosteen, the research of the mangosteens powerful phytonutrients thus far is quite promising.