606 The impact of oral phytochemicals on ultraviolet B-induced erythema response in human skin

Abstract

UV radiation (UVR) induces pyrimidine dimer formation and generates reactive oxygen species leading to skin cancer and photoaging. Sunscreen and protective clothing are primary modalities for photoprotection, but rising skin cancer rates support the rationale for adding systemic photoprotective agents. We showed topical sulforaphane extracts from broccoli reduced erythema resulting from UVB irradiation in humans, and the antioxidant curcumin has well established its anti-inflammatory effects. However, it is not known whether the photoprotective effects of phytochemicals can be achieved through oral delivery. Our study of 20-day duration was designed to evaluate the photobiologic effects of these two edible plant components, separately and in combination. Here we report preliminary results of 6 subjects (3 male/3 female, ages 18-46) with Fitzpatrick phototype I-II. In Phase 1 (Day 1–10), all subjects avoided food or supplements containing phytochemicals. In Phase 2 (Day 11–20), subjects were randomized to receive either the sulforaphane precursor glucoraphanin (450 mg), or curcumin (1000 mg), or both, as oral supplements. On Day 7 [Phase 1] and Day 17 [Phase 2], skin was irradiated with 2-times the minimum erythema dose of UVB. Colorimetry was performed immediately before and 24 hr after UVR. The erythema index was measured as a*, a unit-less ratio of intensities of red reflectivity of the skin, and our photoprotection metric is the percent difference in a* measured at these two time points. The mean reduction in UV-induced erythema following supplementation was 11% (n=6, NS; range = 5% - 36%). The top two responders in erythema reduction (36% and 20%) were recipients of sulforaphane, either alone or with curcumin. These results suggest that select diet-based phytochemical may have utility as oral adjunct to abrogate the negative photobiologic effects of UVR.