Phospholipid-linked coumarin: a fluorescent probe for sensing hydroxyl radicals in lipid membranes.

A fluorescent probe, DPPEC (1,2-dipalmitoylglycerophosphorylethanolamine labeled with coumarin) was developed for detecting hydroxyl radical (*OH) in lipid membranes. The coumarin moiety contributes to the fluorescent detection of *OH and the phospholipids moiety gives a driving force to localize the probe in lipid membranes. DPPEC in liposomal membranes rapidly reacted with *OH and increased the fluorescence intensity, depending on the concentration of *OH. The increase in the fluorescence intensity induced by *OH was effectively suppressed by the addition of DMSO. The probe exhibited a higher fluorescence response to *OH over other reactive oxygen species, such as hydrogen peroxide, nitric oxide, peroxynitrite, alkylperoxyl radical, and hypochlorite. DPPEC would be useful as a new type of fluorescent probe that can localize in lipid membranes and detect *OH efficiently.