The isomerization rate of 2-(2-propenyl)anthracene (22PA) in the lowest excited singlet (S-1) state was investigated in supercritical fluids (SCF); ethane and CO2, as well as in a series of liquid n-alkanes at high pressures. Combining the present results with our preceding ones which had been examined in compressed liquid n-alkane solvents [J. Phys. Chem. A101, 2240 (1997)] we completed the curve of forward isomerization rate constant (k(f)) against solvent viscosity (eta) over the entire friction range. We also discuss the dependence of k(f) on the inverse of solvent self-diffusion coefficient (D-1), which is used as a measure of solvent collisional frequency. The Kramers turnover behavior of 22PA thus observed was compared with our previous result of 2-vinylanthracene [J. Chem. Phys. 103, 5548 (1995)]. The k(f) values of both isomerization reactions around the turnover viscosity region never attains those which are predicted by transition state theory.