Synthesis, photophysical and cytotoxicity evaluation of A3B type mesoporphyrinic compounds

A series of some A3B type mesoporphyrinic compounds were synthesized with superior yields using the microwave irradiation. The prepared compounds were characterized by elemental analysis, FT-IR, UV–Vis, NMR and EPR spectroscopy, which fully confirmed their structures. The spectral molecular absorption properties of the porphyrinic compounds were studied in different solvents and the influence of the solvent polarity on the absorbance maxima was described. Fluorescence emission and singlet oxygen formation quantum yields were evaluated for A3B type mesoporphyrinic compounds and compared with the corresponding symmetrical compounds, revealing high yields for the metal free compounds, followed by the zinc derivatives. The copper mesoporphyrinic compounds are not emissive and only evidence residual capacity for singlet oxygen formation. In order to establish their future potential in biomedical application preliminary toxicological studies, consisting of viability and proliferation of living cells in the presence of the unsymmetrical mesoporphyrinic compounds, were performed in the dark, on a standard cell line of human Caucasian histiocytic lymphoma (U937). The obtained results indicate a very low or no cytotoxicity at all for all compounds under study. Therefore further testing with light activation protocols is recommended in future work.

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► Novel unsymmetrical mesoporphyrins were obtained via microwave assisted synthesis.
► Free basis and zinc porphyrins revealed high fluorescence quantum yields.
► Singlet oxygen formation quantum yields had similar pattern indicating them for PDT.
► Compounds showed no dark toxicity and a slight inhibition of the cell proliferation.