4(1H)-pteridinone, 2-amino-6-(1,2-dihydroxypropyl)-7,8-dihydro- 6779-87-9 7,8-di-H-biopterin 7,8-dihydrobiopterin BIOPTERIN L-erythro-dihydrobiopterin L-erythro-q-dihydrobiopterin P-quinonoid-dihydrobiopterin dihydrobiopterin q-BH2