Water-soluble cyclodextrin (CyD) complexed with porphyrin derivatives with different substituents in the -positions showed different photodynamic activities toward cancer cells under illumination at wavelengths over 600 nm, the most suitable wavelengths for photodynamic therapy (PDT). In particular, aniline- and phenol-substituted derivatives had high photodynamic activity because of the efficient intracellular uptake of the complexes by tumor cells. These complexes showed greater photodynamic activity than photofrin, currently the main drug in clinical use as a photosensitizer. These results represent a significant step toward the optimization of porphyrin derivatives as photosensitizers.

A preparation of a lipid-membrane-incorporated tetraphenylporphyrin was achieved from the corresponding tetraphenylporphyrin·cyclodextrin complexes using an exchange method in both liposomes and cells.

Photoactive molecules with the frameworks of chlorin and/or porphyrin possessing four perfluorinated aromatic rings were conjugated with maltotriose (Mal3) via the nucleophilic aromatic substitution reaction and subsequent deprotection reaction of the oligosaccharide moieties. The resulting oligosaccharide-conjugated molecules are ultimately improved as compared to the previously reported monosaccharide-counterparts in terms of water-solubility. In particular, a water-soluble chlorin derivative surrounded by four Mal3 molecules showed an excellent biocompatibility, strong photoabsorption in the longer wavelength regions, and a very high photocytotoxicity. Thus, the present synthetic route combined with the use of an oligosaccharide was shown to be a straightforward strategy to develop a third generation photosensitizer for photodynamic therapy (PDT).