Hyperflav — perspective photosensitizer for PDT: cell studies
Background: Application of hypericin (an alkaloid from Hypericum perforatum plants) as photodynamic agent may become the next successful step in photodynamic therapy of malignant tumors. Hyperflav — is a purified Hypericum extract designed for the purpose of photodynamic diagnosis. Aim: Present studies investigated the effectiveness in vitro of Hyperflav application as a photosensitizer for photodynamic therapy. Methods: Hyperflav photodynamic activity was assessed in phototoxic cell tests on Jurkat, MT-4 and Namalwa leukemic cell lines. Spectroscopic measurements of Hyperflav solutions were performed. Results: Hyperflav aqueous solubility was maintained in presence of polyvinylpyrrolidone with the most pronounced photodynamic activity at 1:5 (w/w) Hyperflav-PVP ratio. Hyperflav fluorescence spectrum in ethanol exhibits two main peaks around 597 and 647 nm, in accordance with the spectrum of pure hypericin. Fluorescence spectrum of aqueous solution exhibits peaks at 604 and 655 nm and indicates decreasing in fluorescence intensity. Hyperflav at drug dose range of 5 –25 μg/ml and light dose 15 J/cm2 showed a dose-dependent cytotoxicity on tested cell cultures, while dark cytotoxicity was not observed. Light irradiation of cell samples preincubated with 15 μg/ml Hyperflav resulted in 69.9, 76.0 and 78.3% cell death of Jurkat, MT-4 and Namalwa cultures, respectively. Combined preparation of Hyperflav with gold nanoparticles showed low photocytotoxicity (24.2%) in comparison with Hyperflav alone (99.6%) on Namalwa cells. Conclusion: Hyperflav being solubilized in nontoxic aqueous media exhibits in vitro photodynamic activity at doses that do not have dark toxicity, and therefore it meets requirements as a perspective photosensitizer. Further studies, particularly in vivo, are warranted to fully evaluate photodynamic potential of Hyperflav.
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