Polypodium leucotomos (PL) is ineffective in reducing ultraviolet (UV) induced erythema, edema, or tumor initiation when supplementing a plant-based diet in a mouse model of UV-induced carcinogenesis

Summary: Abstract Body: Dietary supplements containing PL are marketed to protect from acute sunburn. PL has been suggested to protect against UV damage through its antioxidant effect. However, the effects of skin-targeting dietary supplements are multifaceted and poorly understood in the acute and chronic photocarcinogenesis setting. The SKH1 mouse model was used to measure the ability of PL to reduce erythema and edema induced by acute UV irradiation with a solar simulator, as well as tumor initiation after chronic UV exposure. In the acute UV studies, SKH1 mice were randomized into PL-containing (n=4) or regular plant-based control diet (n=4) groups, and after 1 week of consuming each diet, the mice were irradiated with escalating doses of UV. The mice were followed for one week after irradiation. In the chronic UV studies, SKH1 mice were fed the PL (n=10) or control diet (n=10) during the 10-week solar simulated UV irradiation period and returned to the control diet after the UV exposure ended. In both studies, mice were regularly photographed to document erythema, edema, tumor formation, and growth. There was no significant difference in erythema, edema, or tumor formation in mice fed the PL diet compared to control (average 6.0 tumors/mouse PL and 3.3 tumors/mouse control p=0.147 analyzed with an unpaired student’s t-test). The levels of metabolites detected in the PL diet were 2-fold higher than the control grain-based diet. In similar studies, reduced UV dose led to decreased erythema and edema in the acute setting and significant decreases in tumor formation in the treated areas after chronic UV exposure. These studies provide crucial preliminary data to establish the true efficacy of PL on acute UV response and cancer risk reduction when supplementing a nutritionally complete plant-based diet. Wendy J. Huss¹, Erin C. Tracy¹, Szabolcs Bozsanyi¹, Ethan D. Herbold^{1, 2}, Perya Bhagchandani^{1, 2}, Sharma Priyanka¹, Rhea C. Rodrigues¹, Ruby Acquah¹, Sean P. Murphy¹, Lei Wei¹, Barbara Foster¹, Gyorgy Paragh¹ 1. Roswell Park Comprehensive Cancer Center, Buffalo, NY, United States. 2. University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY, United States. UV Biology/Injury and Non-melanoma Cancers