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A New Naturally Derived Photosensitizer and Its Phototoxicity on Head and Neck Cancer Cells
Author(s) -
Lim Siang Hui,
Lee Hong Boon,
Ho Anthony Siong Hock
Publication year - 2011
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2011.00939.x
Subject(s) - photosensitizer , phototoxicity , chemistry , singlet oxygen , intracellular , photodynamic therapy , biophysics , flow cytometry , cell cycle , cell culture , apoptosis , photochemistry , biochemistry , in vitro , microbiology and biotechnology , biology , oxygen , organic chemistry , genetics
In our screening for photosensitizers from natural resources, 15 1 ‐hydroxypurpurin‐7‐lactone ethyl methyl diester (compound 1 ) was isolated for the first time from an Araceae plant. To evaluate the efficacy of compound 1 as a photosensitizer for head and neck cancers, compound 1 was studied in reference to a known photosensitizer pheophorbide‐a (Pha), in terms of photophysical properties, singlet oxygen generation and in in vitro experiments (intracellular uptake and phototoxicity assays) in two oral (HSC2 and HSC3) and two nasopharyngeal (HK1 and C666‐1) cancer cell lines. In this study, compound 1 exhibited higher intracellular uptake over 24 h compared with Pha in both HSC3 and HK1 cells. When activated by ≥4.8 J cm −2 of light, compound 1 was slightly more potent as a photosensitizer than Pha by consistently having marginally lower IC 50 values across different cell lines. In flow cytometry experiments to study the mechanism of photoactivated cell death in HSC3, compound 1 was observed to induce more pronounced apoptosis compared with Pha, which may have been driven by the transient G 2 /M cell cycle block which was also observed. These promising results on compound 1 warrant its further investigation as a clinically useful photodynamic therapy agent for head and neck cancer.