Synthesis and evaluation of new tetrapyrrole derivatives with photodynamic anti-tumor effects

Abstract

As a promising anti-tumor method, photodynamic therapy (PDT) has garnered increased interest over the past decades. Since the efficacy of PDT relies on the properties of photosensitizers, tremendous efforts have been exerted in the quest for novel photoactive agents with long wavelength absorbance and high phototoxicity. In this investigation, a series of five tetrapyrrole derivatives were newly synthesized and evaluated. They all manifested sharp UV–vis absorption peak at ∼680 nm, high molar extinction coefficient (>74200 L mol−1 cm−1), impressive reactive oxygen species generation abilities and obvious photo-damage on cancer in vitro and in vivo. Among them, I4 displayed the most excellent singlet oxygen generation slope (K = 0.0531 s−1, ΦΔ = 0.87), the strongest anti-proliferation effects towards human esophageal cancer cell line Eca-109 in vitro, and more remarkable tumor inhibition rates (90.2 %) than m-THPC in vivo. Subcellular localization experiments demonstrated that I4 could distribute in mitochondria, endoplasmic reticulum and lysosomes. Hence, compound I4 could be viewed as a potential photosensitizer drug for further studies in PDT.