2H-1-Benzopyran-3,4,5,7-tetrol, 2-(3,4-dihydroxyphenyl)-2-[[2-(3,4-dihydroxyphenyl)-3,4-dihydro-5,7-dihydroxy-2H-1-benzopyran-3-yl]oxy]-3,4-dihydro-, 95%, 25g