1,3a,10,11a,12,14a,19,20a-Octahydro-4,9,15,18-tetrahydroxy-6,10,19-trimethyl-2H,8H-difuro[3,2-b:3,2-b]pentapheno[2,3-d:10,11-d]dipyran-2,5,8,13,16,17-hexone