Amelioration of UV radiation-induced photoaging by a combinational sunscreen formulation via aversion of oxidative collagen degradation and promotion of TGF-β-Smad-mediated collagen production.

The presence of 40-50% more UV radiation in high altitude areas renders the plethora of sunscreen products available in the market virtually ineffective. In this light of event, four US FDA approved UV filters were combined with melatonin and pumpkin seed oil to produce a broad spectrum sunscreen cream, which is envisaged to provide optimum sunprotection along with enhanced antioxidant activity. The objective of this study is to evaluate the protective effect of the sunscreen cream against UV radiation-induced skin photoaging in adult Wistar albino rats and identify its possible underlying mechanism. Wistar rats were exposed to broad spectrum UV radiation for 28 days. The test group received the sunscreen formulation dermally every day prior to UV radiation. The effects of the formulation against UV induced symptoms; viz. skin thickness and edema, in vivo antioxidant activities, inflammatory cytokines, collagen content, histopathological examination and expression of specific genes established the protective activity of the formulation. The test formulation was able to mitigate the harmful effects of UV radiation by increasing in vivo SOD, GSH-Px, CAT and collagen levels; decreasing skin edema, skin thickness and cytokines like IL-6, IL-1β, TNF-α and TGF-β1. UV radiation induced changes in histological architecture and arrangement of collagen and elastin fibers were also prevented by the test formulation. Finally, the formulation was able to regulate the expression of COL3A1, COX-2, bFGF, VEGF-C, Smad2, Smad4, Smad7 genes which induced significant photoprotective activity. The sunscreen formulation ameliorated UV induced photoaging by preventing oxidative collagen degradation and augmentation of TGF-β-Smad-mediated collagen production.