Figure 2

Two versions of the D. rerio embryotoxicity assay for DAE-modified peptides: timelines, peptide photostates, ages of larvae, and definitions of the measured characteristics. (A) Direct application of the non-photoswitchable parent GS 1 or of the ring-open photoform of our prototype 2_, and the corresponding killing curves for 1 (C, top, black) and 2 (C, bottom, red). (B) “Photoactivation” assay: initial application of the ring-closed photoform, incubation in darkness, followed by in situ photoconversion into the ring-open(ed) photoform, with the corresponding killing curves for 1 (D, top) and 2 (D, bottom, green for ring-closed, red for ring-open isomers). The latter panel illustrates the “phototherapeutic safety window” (green arrow) as the difference in toxicity between the ring-closed and the ring-open isomers upon photoactivation.