IC50 valuesa (μM) for compounds 1 and 2 and dark/light ratio (with and without irradiation) against human CTSB and human breast cancer cell lysates.

aInhibitory activities were determined with the fluorogenic substrate Z-Arg-Arg-AMC.Reactions were conducted in the dark (no irradiation) and light (λirr = 395–750 nm) for 45 min with a 250 W tungsten halogen lamp and H2O filter. The standard deviations were within 40% of the IC50 values and the curves were plotted against log [inhibitor] with 100% activity set equal to the control reaction in the absence of inhibitor. Assay conditions: activator buffer containing 5 mM EDTA, 10 mM DTT, pH 5.2 and assay buffer containing 0.6 mM CaCl2, 0.6 mM MgCl2, 25 mM piperazin-N-N‘-bis[2-ethanosulfonic acid (disodium salt)], pH 7.3. DMSO was used as a negative control. Substrate concentration was 150 μM and CTSB concentration was 10 nM. Data shown are from 3 independent experiments.IC50 valuesa (μM) for compounds 1 and 2 and dark/light ratio (with and without irradiation) against human CTSB and human breast cancer cell lysates.