PDT of head and neck cancer with redaporfin

Photodynamic therapy with a new bacteriochlorin derivative: Characterization and in vitro studies

Photodynamic therapy presents a therapeutic choice that can be utilized to treat diverse neoplasms. In this technique, the critical element is a photosensitive molecule that absorbs light energy and transfers it to molecular oxygen or biological molecules to form reactive oxygen species, thus inducing irreversible damage to target cells and ultimately leading to cell death. Bacteriochlorin derivatives are employed as photosensitizers (PSs), possessing light-absorbing capacity in the near-infrared region. The objective of this study was to prepare a semi-synthetic bacteriochlorin from Rhodopseudomonas faecalis and adding Trizma® to improve solubility. Cell viability tests, flow cytometry (apoptotic and necrotic cells were identified by Annexin V and propidium iodide), and confocal microscopy were used to evaluate the photoactivity of bacteriochlorin-Trizma (Bchl-T) in fibroblast (HFF-1-control cells) and breast cancer (MCF-7 cells-target cells) cells. At concentrations above 0.5 μM, Bchl-T demonstrated 80 % cell death, presenting the highest PS interaction (via fluorescence microscopy) with lysosomes, mitochondria, and the endoplasmic reticulum; the cell death type was revealed as apoptosis (via cytometry). Our findings indicated the suitability of Bchl-T for future application in photodynamic therapy against cancer cells by inducing apoptosis.

[Primary screening of substances-photosensibilizers of the bacteriochlorin range for photodynamic therapy of malignant neoplasms]

This paper presents a primary screening of bacteriochlorin-type compounds with aminoamide, propyl and carbohydrate substituents aimed for development a new generation photosensitizers (PS) for photodynamic therapy of malignant tumors. Absorption and fluorescence spectral characteristics of the compounds, their storage stability in solutions under dark conditions and light exposure, photo-induced and dark cytotoxicity against human HEp2 tumor cells have been studied. It has been shown that the dyes with aminoamide substituents have an absorbtion maximum at 754±2 nm in the long wavelength region and they are not stable during storage (the specific fluorescence intensity decreased by 33-56% during 24 hours). The long wavelength region absorption of the propyl and carbohydrate substituted compounds varied in the range 780-831 nm, they were stable in solutions during storage and under light irradiation. Except the dye with a carbohydrate residue in the exocycle E, all PS exhibited the high photo-induced activity and low level of the dark cytotoxicity. The highest photo-induced cytotoxicity was observed for compounds with aminoamide substituents inthe macrocyclic ring (IC 50 values ranged from 17 nM to49 nM after 2 hour incubation with PS followed by exposure to the 10 J/cm 2 dose of red light). Taking into account the totality of the physico-chemical and biological properties, as well as manufacturability of production, O-propyloxime-N-propoxybacteriopurinimide methyl ester was chosen as the most promising candidate compound for further investigations.