Supplemental Figure Legends

Supplemental Figure legends

Supplemental Figure 1: Structural formulae of representative members of the imidazoacridinone family. C-1330, C-1375 and C-1379 are not substrates of MDR efflux pumps including ABCG2, whereas C-1311 is an ABCG2 substrate.

Supplemental Figure 2: Lack of co-localization of C-1330 and MitoTracker red in A549 and A549/K1.5 cells. A549 (A-C) and A549/K1.5 cells (D-F) were viably stained with Hoechst 33342 (blue nuclear fluorescence) along with 100 nM MitoTracker red for 1 h (Red fluorescence; A, D) or 10 µM C-1330 for 30 min (green fluorescence; B, E). Merged images of MitoTracker red and C-1330 are shown in panels C, F.

Supplemental Figure 3: Photoexcitation of IAs results in ROS generation. Generation of singlet oxygen (A) and superoxide anion (B) after photosensitization of C-1375 and C-1379 was followed as described in Materials and Methods. The inset in Panel A shows singlet oxygen formation after photoexcitation of the established photosensitizers Rose Bengal and riboflavin.

Supplemental Movie legends:

Supplemental movie 1: Live cell imaging of C-1330 loaded A549 cells. A549 cells were incubated with 10µM C-1330 (2hrs). Live cell imaging was performed using a Zeiss Axiovert 200 inverted fluorescent microscope (Carl Zeiss, Oberkochen, Germany). Time lapse photos were taken every second during constant illumination for 36 seconds, the movie shows 3 frames per second. Scale bar included.

Supplemental movie 2: Live cell imaging of C-1330 loaded A549/K1.5 cells. A549/K1.5 cells were incubated with 10µM C-1330 (2hrs). Live cell imaging was performed using a Zeiss Axiovert 200 inverted fluorescent microscope (Carl Zeiss, Oberkochen, Germany). Time lapse photos were taken every second during constant illumination for 36 seconds, the movie shows 3 frames per second. Scale bar included.