Synthesis and radiosensitizing properties of brominated tetrapyridine porphyrins

Abstract

Brominated derivatives of tetrapyridinium copper porphyrin were prepared via bromination of the β-positions (pyrrole rings) and/or the peripheral alkyl side-chains attached to the pyridine moieties. The radiosensitizing properties of these new cationic, brominated porphyrins were tested on MDA-MB-231 breast cancer cells in vitro using a 60 Co source or an X-ray irradiator. The non-brominated porphyrin and the porphyrin containing bromines at β-positions only were devoid of any radiosensitizing activity. However, a pronounced radiosensitizing effect was observed with the porphyrin containing bromo atoms at both β-positions and the peripheral side-chains. A similar radiosensitizing effect was detected for different radiation energies, suggesting that high energy photons could be used to treat tumors in conjunction with this novel brominated, porphyrin-based radiosensitizer.