F is the maximum fluorescence intensity (0 µM of APV) and Ft is fluorescence intensity at time t (min). Linear regression analysis yielded straight lines (R2 >0.9711) and the slope of each line yields the rate constant (kobs, min−1). kobs values: −0.3027 (± 0.02341) for 0 µM, −0.2239 (± 0.01459) for 0.5 µM, −0.1638 (± 0.007995) for 1.0 µM, −0.0890 (± 0.004938) for 2.0 µM, −0.05704 (± 0.00144) for 3.5 µM, and −0.03766 (± 0.00191) for 5.0 µM.