Hello Imadoudini Hassimi Safia
Photosensitizer (PS) is one of the components in addition to oxygen and light that work in coordination in Photodynamic therapy (PDT). These components are not toxic to cells individually, but when irradiated, these can initiate a photochemical reaction that generates highly reactive singlet oxygen (1O2), and cause significant toxicity, leading to cell death.
This photoactivation exerts an anticancer effect via apoptosis, necrosis, and autophagy of cancer cells. Various natural compounds that exhibit photosensitizing potentials have been identified from medicinal plants and have been found to be safe in comparison with synthetic compounds. Hiporfin includes hematoporphyrin, porphyrin polymer, hydroxyethylvinylporphyrin and protoporphyrin.
One can describe Photodynamic therapy in two stages,
1) The first is administration of the PS and
2) The second stage is the irradiation.
Generally, the effect of PDT is affected by the PS type, dosage, light influence, as well as exposure time.
There are three types of lights ranging from 400 to 800 nm that are commonly used in PDT, namely, blue, red, and infrared lights. Among them, blue light penetrates the tissue the least when compared to red and infrared lights. The wavelengths below 800 nm are mostly used in PDT than higher wavelengths (above 800 nm) due to their lack of photodynamic reactions. The choice of light source is commonly based on PS nature, absorption spectra of PS, location, and size and characteristics of the infected tissue.
The important properties of a PS is
a. Non-toxic nature during the absence of light.
b. Increasing activity of the phytocompounds after irradiation by light making them good photosensitizing candidates for PDT.
c. Lastly, the important feature that makes photoactive plant compounds suitable photosensitizers is their absorption maxima at 400–700 nm, which is biologically compatible.
You may want to refer to the articles attached below for more information.
Article Role of Photoactive Phytocompounds in Photodynamic Therapy of Cancer
Article Reactive oxygen species generating systems meeting challenge...
https://www.oaepublish.com/articles/2394-4722.2018.83
Article Photochemotherapy of Glioma Cells by Visible Light and Hematoporphyrin
Best.
