In vitro Assessment of sun protection factor (SPF) and Antioxidant activity of Viola odorata extracts

Abstract

The harmful effects of sunlight on the skin have triggered several studies. They concentrated on the synthesis or extraction of natural compounds that can absorb ultraviolet (UV) radiation. In this study, we investigated the in vitro photo-protective potential of Viola odorata flowers extracts, in three states (fresh, dried, frozen), using three solvents (chloroform, ethyl acetate, ethanol) by sequential extraction. In vitro SPF values were determined by spectrophotometric method. Antioxidant activity was tested by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Total phenolic content (TPC) was measured using Folin-Ciocalteu method. The ethanolic extract fraction, at the concentration of 2 mg/ml, from the three flowers states had the best SPF values (27.249, 26.978, 27.907) respectively, followed by ethyl acetate extract fraction of dried flowers (SPF=21.11). The highest DPPH inhibition (about 85%) was also obtained in ethanolic extract fraction from the three states of flowers. The ethanolic extract fraction of fresh flowers showed the highest total phenolic content (18.575 mg GAE/g crud extract), followed by ethanolic extract fraction of dried flowers (15.06 mg GAE/g crud extract). There was a significant positive correlation between SPF values and each of antioxidant activity (R=0.92) and TPC (R=0.748) in the different extract fractions. Our results showed that ethnolic Viola odorata flowers extract, in different states, has a great potential to be used as a sunscreen agent due to its polyphenol content, which is also associated with strong antioxidant activity.