Effect of grape seed extract on skin fibroblasts exposed to UVA light and its photostability in sunscreen formulation

Abstract Background Grape seed extract (GSE) is rich in polyphenolic compounds, particularly (+)‐catechin (C) and (‐)‐epicatechin (EC). Strong antioxidant activity of these compounds makes GSE to be value‐added to the cosmetics with anti‐aging properties. However, a lack of stability in different environmental conditions makes GSE challenging for the development of photostable cosmetic sunscreen products. Aims To evaluate photoprotective effects of GSE on human dermal fibroblasts irradiated with UVA light and assess photostability of catechins in cream formulations containing GSE alone or in combination with octyl methoxycinnamate (OMC). Methods MTT assay was used to assess protective effects of GSE on fibroblasts irradiated with UVA light. A photostability of C and EC in GSE and in cream formulation containing GSE was investigated using high‐performance liquid chromatography and confirmed by reflection and transmission spectrophotometry using Transpore™ tapes and polymethacrylate (PMMA) plates as substrates. Results High UVA doses damaged fibroblast structure and inhibited their growth. However, GSE increased cell viability and effectively protected them from UVA damage. Photostability of C and EC was achieved by combination of GSE and OMC that also improved absorption capacity of UV filter and increased overall efficacy of formulation. PMMA plates showed better applicability for in vitro photostability testing of sunscreen formulations. However, despite the instability of Transpore® tape under heat from UV exposure, it can still be economically a substrate of alternative choice for screening. Conclusions GSE can be used as an effective and sustainable natural resource for prevention of UV‐induced skin damage providing long‐term protection against premature skin aging.