5-{[(4-{[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)-3,4,5,6-tetrahydro-2H-pyran-2-yl]oxy}phenyl)methyl]oxy}-3-({[(4-{[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)-3,4,5,6-tetrahydro-2H-pyran-2-yl]oxy}phenyl)methyl]oxy}carbonyl)-3-hydroxy-5-oxopentanoic acid