A synthesis of new biologically active fluorescent cyclic nucleotides of general formula: <IMG> wherein X=OH and Y=NH2 or X=NH2 and Y=H and L is a fluorescent group of the class of 5 (or 6)-thioacetamido-fluorescein or of 5 (or 8)-(2-thioacetamido-ethyl)-amino-naphthalene-1-sulphonic acid. The fluorescent cyclic nucleotides in particular have biological activity in an ability to activate the permeability of retinal rod membranes, an ability to bind retinal rod membranes to the sites to which natural cyclic nucleotides bind and stability to hydrolysis.
BIOLOGICALLY ACTIVE FLUORESCENT CYCLIC NUCLEOTIDES