Showing structure for (2r,3r)-5,6,8-trihydroxy-2,3-dimethyl-9-[(2r)-5,6,8-trihydroxy-2-methyl-4-oxo-2h,3h-naphtho[2,3-b]pyran-9-yl]-2h,3h-naphtho[2,3-b]pyran-4-one