Журнал наномедицинских и биотерапевтических открытий
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Protamine conjugated fluorochromes: A new photosensitizer for photodynamic tumor therapy

Hoonsung Cho

The Photodynamic Therapy (PDT) is a promising alternative therapy that could be used adjunct to chemotherapy and surgery for curing cancer causing tissue destruction by visible light in the presence of a Photosensitizer (PS) and oxygen. Protamine is a high arginine peptide with membrane translocating and nuclear localizing properties. The reaction of an NHSester of Methylene Blue (MB) and clinical Protamine (Pro), to yield MB-Pro, was described in this context and demonstration of photo-toxicity which clinical protamine improved PDT effect was performed. The reaction between clinical Protamine (Pro) an NHS ester of MB is a solution phase reaction with the complete modification of the protamine peptides which feature a single reactive amine at the N-terminal proline and single carboxyl group at the Cterminal arginine. The aim of this study was to find a new type of Photosensitizer (PS) for PDT on in vitro and in vivo experiments and to assess the anti-tumor effect of PDT using the protamine conjugated-PS on the cancer cell line. Photodynamic cell death studies show that the MB-Pro produced has more efficient photodynamic activities than MB alone, causing rapid light induced cell death. The attachment of MB to clinical Pro, yielding MB-Pro, confers the membrane internalizing activity of its high arginine content on MB and can induce a rapid photodynamic cell death, presumably due to cell membrane rupture induced by light. The PDT using MBPro for HT-29 cells was very effective and those findings suggest that MB-Pro is one of candidate for photosensitizer in solid tumors.