Gravar-mail: 4,5,7,8,17-Penta­hydr­oxy-14,18-dimethyl-6-methyl­ene-3,10-dioxapenta­cyclo­[9.8.0.0(1,7).0(4,19).0(13,18)]nona­dec-14-ene-9,16-dione methanol solvate dihydrate