(16α,17β)- Estra-1,3,5(10)-triene-3,4,16,17-tetrol-16,17-diacetate is an intermediate in the synthesis of 2-Hydroxyestriol (H949313), which is used to characterize oxidative metabolites of 17β-estradiol and estrone formed by 15 selectively expressed human cytochrome P 450 isoforms.