<i>In Vitro</i> Demonstration of Apoptosis Mediated Photodynamic Activity and NIR Nucleus Imaging through a Novel Porphyrin

We synthesized a novel water-soluble porphyrin <b>THPP</b> and its metalated derivative <b>Zn-THPP</b> having excellent triplet excited state quantum yields and singlet oxygen generation efficiency. When compared to U.S. Food and Drug Administration approved and clinically used sensitizer Photofrin, <b>THPP</b> showed <i>ca.</i> 2–3-fold higher <i>in vitro</i> photodynamic activity in different cell lines under identical conditions. The mechanism of the biological activity of these porphyrin systems has been evaluated through a variety of techniques: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, comet assay, poly­(ADP-ribose)­polymerase (PARP) cleavage, CM-H₂DCFDA assay, DNA fragmentation, flow cytometric analysis, fluorescence, and confocal microscopy, which confirm the apoptotic cell death through predominantly reactive oxygen species (ROS). Moreover, <b>THPP</b> showed rapid cellular uptake and are localized in the nucleus of the cells as compared to Hoechst dye and Photofrin, thereby demonstrating its use as an efficient sensitizer in photodynamic therapy and live cell NIR nucleus imaging applications