Noun
biopterin (countable and uncountable, plural biopterins)
English Wikipedia has an article on:biopterinWikipedia
A coenzyme produced within the body, an oxidized degradation product of tetrahydrobiopterin. Defects in biopterin synthesis or regeneration can cause a form of hyperphenylalaninemia, and biopterin deficiency has been associated with dystonia and rabies.