Dose response cytotoxicity studies with naturally derived photosensitizers against cancer cells

Breast cancer has been recorded as the second leading type of cancer with 2.3 million new cases and 670 000 deaths in 2022. Over time conventional breast cancer treatments such as surgery, radiation therapy, chemotherapy, and hormone therapy, have become less effective due to severe side effects and multidrug resistance. Adopting a complementary and/or alternative treatment strategy can be a significant solution to overcome such limitations. Exploring the potential of an alternative treatment modality like Photodynamic Therapy (PDT) in using naturally derived photosensitizers (PSs) can prove to be a promising anticancer strategy against breast cancer. Several natural products have been used in traditional medicine throughout history for different ailments with success. The diversity of plants, their beneficial primary and secondary phytocompounds make them advantageous as cost-effective cancer treatment strategy with minimal induced side effects. This study aims to demonstrate the phototoxic potential of naturally derived photosensitizers (PS) pheophorbide-a and hypericin to treat MCF-7 breast cancer cells. Hypericin and pheophorbide-a mediated PDT at 0.01 – 0.2 and 0.1 – 1.2 μM at 1 J/cm² fluency with 595 nm and 660 nm laser irradiation used to treat MCF-7 cells. Post treatment cellular responses were evaluated using 3-(4,5-dimethyl-2- thiazyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, morphological analysis, and flow cytometry (Annexin V/PI). Results showed that both PSs showed significant phototoxic effects on MCF-7 cells via induction of apoptosis and further in vivo investigation is a viable option.