Photodynamic therapy (
PDT) with a suitable
photosensitizer molecule is a promising anticancer treatment. We evaluated two
chlorin molecules as potential
photosensitizers, methyl
pyropheophorbide a (
MPPa) and N-methoxyl purpurinimide (NMPi), against A549 human
lung adenocarcinoma cells in vitro as well as in A549
tumor-bearing mice in vivo. Cell viability, microscopy, and fluorescence-activated cell sorting (FACS) analyses were performed for the in vitro studies.
MPPa and NMPi showed high
phototoxicity in vitro, which was dependent on the concentration of the
photosensitizers as well as the light irradiation time. In the animal study,
tumor volume change,
tumor surface alterations, and
hematoxylin &
eosin (H&E) and terminal deoxyribonucleotidyl transferse-mediated dUTP nick-end labelling (TUNEL) staining analyses were performed and compared between small (
tumor volume of 50 mm³) size of initial
tumors.
MPPa and NMPi showed high anticancer efficacy against small-size
tumors, indicating that early treatment with
PDT is effective. Especially, repeated two times
PDT with NMPi allowed almost complete eradication against small-size
tumors. However,
MPPa and NMPi were not effective against large-size
tumors. In conclusion, the two
chlorin derivatives,
MPPa and NMPi, show good anticancer efficacy as promising
photosensitizers for
PDT in vitro and in vivo. Moreover, their activity in vivo was significantly dependent on the initial
tumor size in mice, which confirms the importance of early
cancer treatment.