1,1,2,2,3,3,4,4,9,9,10,10-Dodecahydro-3α,3α,8,8-tetrahydroxy-3,3-dimethyl-4α,4α-di[(R)-1-(acetyloxy)ethyl]-1,1,9,9,10,10-hexaoxo(7,7-bianthracene)