Synthesis and antitumor study of novel porphyrin–coumarin derivatives for chemotherapy and photodynamic therapy

Photodynamic therapy (PDT) is attractive in cancer treatment because of its non-invasive and low side effects. In this study, we synthesized 20 porphyrin–coumarin compounds via condensation reactions of porphyrins with coumarin derivatives. In the singlet oxygen (1O2) assay, DPBF fluorescence was quenched by 85% after 10 s of light irradiation; the fluorescence of DPBF almost disappeared at 30 s by light irradiation. This indicates that the porphyrin–coumarin compounds have excellent 1O2 generation efficiency. Moreover, porphyrin–coumarin compounds showed different inhibitory effects on A549 and HepG2 cells under light irradiation. Whereas in dark conditions, compounds with shorter alkyl chains showed antitumor activity, the extension of branched and alkyl chains decreased the activity of the compounds. Therefore, accessing coumarin derivatives with shorter alkyl chains to porphyrins achieves PDT and chemotherapy. Additionally, the insertion of metal Zn into porphyrins also enhances the PDT effect of the compounds.