Skin protection against solar UV radiation by natural plant products: Extracts from elder fruit (Sambucus nigra L.)

Abstract

Solar radiation has harmful effects on exposed skin, producing accelerated aging processes (wrinkles, dryness, telangiectasia, dyspigmentations). Also, there is an increased ROS generation in skin exposed to the UV-A and UV-B radiation. This results in oxidative stress, photodamage of skin macromolecules and photocarcinogenesis processes. In order to prevent this, botanical extracts with antioxidant properties can be used in anti-photoaging preparations, as a substitute for traditional sunscreen products. Plant extracts, rich in natural polyphenols, exert fewer sensitization effects on skin and are very effective against oxidative damaging caused by UV radiation. The aim of this study was to evaluate the antioxidative activity of different elder (Sambucus nigra L.) fruit extracts. Active components of S. nigra, such as polyphenols, have an important biological activity. Fruit extracts were obtained by the maceration method using four different solvents (methanol - ME, propylene glycol 45% v/v - PE, ethanol 70% v/v - EE and distilled water - WE). To study antioxidant activity we used different in vitro assays: 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP) assay and β-carotene bleaching assay. The concentrations at which 50% of the DPPH radicals were scavenged (IC50) were 3.54, 3.94 and 12.07 mg/ml for the samples EE, ME and PE, respectively. The sample WE showed a stronger scavenging activity (IC50 value was 2.62 mg/ml). FRAP values were 242.29 and 686.43 μmol Fe2+/g of dry extract for PE and ME samples, respectively. Higher values were obtained using the EE and WE samples, 793.54 and 934.81 μmol Fe2+/g of dry extract, respectively. Sample EE was the most active in the β-carotene bleaching assay (IC50 was 0.235±0.004 mg/ml). Extracts WE and PE showed similar, but lower percentage of inhibition of β-carotene bleaching. FRAP assay showed a significant (p < 0.05) negative correlation (r = - 0.975) with radical scavenging capacity (IC50 values). The extract WE (distilled water was used as a solvent) exhibited the highest radical scavenging activity and had the highest ferric reducing potential.