Significance: Side effects of many cancer treatments are associated with the production of reactive oxygen species (ROS) in normal tissues. This explains why patients treated by photodynamic therapy (PDT) often suffer from skin photosensitization, whereas those subject to radiotherapies frequently experience damages in various organs, including the skin.

Aim: Catechin, which belongs to the natural flavanols family, is well known for its antioxidant properties. Hence, our main objective was to investigate whether catechin can reduce damages induced by PDT using protoporphyrin IX (PpIX-PDT), an endogenous photosensitizer commonly used in dermatology.

Approach: An in vivo model, the chick embryo chorioallantoic membrane (CAM), was used for this study. An amount of 20 mu l of a solution containing 5-aminolevulinic acid, a natural precursor of PpIX, was applied topically on the CAM 4 h before PDTs (405 nm, 2.9 mW/cm(2), 1.2 J/cm(2)). Catechin was applied at different concentrations (1 to 50 mu M) and times (0 to 240 min) before PDT. In addition, we assessed the potency of catechin to reduce the PpIX fluorescence photobleaching induced by PDT.

Results: We observed that catechin significantly reduces the vascular damages generated by PpIX-PDT. Moreover, we have shown that catechin inhibits PpIX photobleaching.

Conclusions: These observations suggest that catechin significantly reduces the level of ROS produced by PpIX-PDT. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License.