Photoprotection assessment of olive (Olea europaea L.) leaves extract standardized to oleuropein: In vitro and in silico approach for improved sunscreens.

Abstract Olive leaves contain higher amount of polyphenols than olive oil and represent a waste product from olive harvest and pruning of olive trees. The most abundant compound in olive leaves is oleuropein. Benefits of the topical application of olive leaves extract were previously reported, but little information is available on its photoprotective potential and the result of the association of this extract with organic UV filters in topical sunscreen formulations. The olive leaves extract photoprotective potential is less explored for both oral and topical photoprotection in comparison with other plants extracts and polyphenols, such as Polypodium leucotomos extract and resveratrol. There are increasing efforts towards developing more efficient sunscreens and a photoprotection assessement along with a better understanding of the photochemistry of naturally occurring sunscreens could aid the design of new and improved commercial sunscreen formulations. This study was designed to investigate the photoprotective potential of olive leaves extract standardized for oleuropein performing a set of in vitro and in silico tools as an innovative approach, highlighting yeast assays, in vitro Sun Protection Factor (SPF) and molecular modelling studies of UV absorption. This study supports the use of olive leaves extract for photoprotection, as an effective photoprotective, anti-mutagenic and antioxidant active, also showing a synergistic effect in association with UV filters with an improvement on in vitro SPF of sunscreen formulations. Graphical Abstract Unlabelled Image Highlights • Olive leaves extract standardized to oleuropein is investigated for sunscreens. • OLE increases photoprotection in yeasts ogg1 mutant exposed upon SSL. • OLE show anti-mutagenic effect in yeasts ogg1 mutant exposed upon SSL. • In vitro SPF improvement due to the synergism of OLE and UV filters. • Theoretical studies of UV absorption mechanisms of oleuropein and resveratrol. [ABSTRACT FROM AUTHOR]