What is described are compounds of formula (1) wherein L1 is derived from an ether (R1—OR2)m, wherein R1 and R2 are independently selected and are derived from a hydrocarbon having 1 to 12 carbon atoms, with m being an integer from 1 to 4, or from a hydrocarbon R having 1 to 20 carbon atoms; F is unsubstituted or substituted pyrene as a fluorophore; Q is a quencher, and L2 is C(O)-L1 or C(O)-L1-NH, wherein L1 is as defined above. These compounds may be used to determine the activity of phospholipase A2, in particular PAF-AH.