Endoplasmic reticulum targeting tin porphyrins with Oligoethyleneglycol chains: Synthesis, DFT studies and anti-cancer activities

The A<inf>2</inf>B<inf>2</inf> and A<inf>3</inf>B type porphyrins and their tin(IV) complexes are reported bearing two or three oligoethyleneglycol (OEG) chains at the meso‑positions. The other meso‑positions of tin(IV) porphyrins were substituted with N-butylcarbazole and triphenylamine moieties. The structures of all eight porphyrins were confirmed by IR, NMR and MALDI-mass; their UV–vis absorption, fluorescence properties were also analysed. The cellular uptake and anti-cancer activities of four tin porphyrins were examined in lung cancer cells. The presence of three OEG chains enhanced their cell permeability and bioactivity against cancer cells. A<inf>3</inf>B type tin porphyrins with three OEG chains displayed endoplasmic reticulum (ER) colocalization and generated ROS after light exposure as judged by confocal microscopy. The in-vitro photocytotoxicity studies revealed excellent IC<inf>50</inf> values between 0.76 to 1.36 μM for A<inf>3</inf>B type porphyrins. Furthermore, these porphyrins were non-toxic in dark conditions, suggesting their potential as PDT agents for cancer treatment in near future.