6-(b-D-Galactopyranosyloxy)-9-(4-methoxy-2-methylphenyl)-3H-xanthen-3-one

9-(4′-Methoxy-2′-methylphenyl)-6-(b-D-galactopylanosyloxy)-xanthen-3-one)

6-(b-D-Galactopyranosyloxy)-9-(4-methoxy-2-methylphenyl)-3H-xanthen-3-one (MGBG) is a hydrophilic activatable fluorescence probe that has been shown to be effective in photodynamic therapy. MGBG is activated by light and has a high affinity for esterases, which are found in many tissues. The fluorescence of the MGBG is quenched by the esterase enzymes, but when it is exposed to light and oxygen, the probe becomes activated and its fluorescence increases. MGBG can be used as a fluorescent probe for intraperitoneal tumor resection or as a fluorescent imaging agent in optical microscopy.