The Synergistic Behavior of Antioxidant Phenolic Compounds Obtained from Winemaking Waste's Valorization, Increased the Efficacy of a Sunscreen System.

Grape pomace retains polyphenols in the peels and in the seeds after winemaking, which is indicative of the high valorization potential of this industrial waste. There is strong evidence that phenolics are robust antioxidants and confer photoprotection; thus, it is rational to apply these active compounds from winemaking waste to sunscreens, in order to increase UV protection. Despite the importance of this class of cosmetics to public health, more efficacious strategies are still needed to overcome the problems caused by the photoinstability of some UV filters. The hydroethanolic extract of Vitis vinifera L. grapes was obtained by percolation and then lyophilized. Six formulations were developed: Type I-cosmetic base and UV filters; Type II-cosmetic base and extract; and Type III-cosmetic base, extract and UV filters. Each formulation was prepared in the pHs 5 and 7. The antioxidant activities of the samples were measured by DPPH• and expressed in Trolox® equivalents (TE), and their photostability and in vitro sun protection factor (SPF) were analyzed by diffuse reflectance spectrophotometry. The anti-radical efficiencies observed in the formulations with grape extract were: (II) 590.12 ± 0.01 µmol TE g-1 at pH 5 and 424.51 ± 0.32 µmol TE g-1 at pH 7; (III) 550.88 ± 0.00 µmol TE g-1 at pH 5 and 429.66 ± 0.10 µmol TE g-1, at pH 7, demonstrating that the UV filters, butylmethoxydibenzoyl methane, ethylhexyl methoxycinnamate and ethylhexyl dimethyl 4-aminobenzoic acid had no influence on this effect. The photoprotective efficacy and the photostability of formulation III containing the extract and UV filters at pH 5 suggested that a synergism between the active molecules provided an 81% increase in SPF. Additionally, this was the only sample that maintained a broad spectrum of protection after irradiation. These results confirmed that the grape pomace extract has multifunctional potential for cosmetic use, mainly in sunscreens, granting them superior performance.

Novel approaches mediated by tailor-made green solvents for the extraction of phenolic compounds from agro-food industrial by-products.

An environmentally friendly method for the phenolic compound extraction from agro-food industrial by-products was developed in order to contribute with their sustainable valorization. A Natural Deep Eutectic Solvent was chemometrically-designed for the first time and compared with traditional solvents in terms of analyte stabilization. The combination of lactic acid, glucose and 15% water (LGH-15) was selected as optimal. A high-efficiency ultrasound-assisted extraction mediated by LGH-15 prior to HPLC-DAD allows the determination of 14 phenols in onion, olive, tomato and pear industrial by-products. NADES synthesis as well as the extraction procedures were optimized by Response Surface Methodology. Thus, phenolic determination in these complex samples was achieved by a simple, non-expensive, eco-friendly and robust system. The application to different matrices demonstrated the versatility of the proposed method. NADES opens interesting perspectives for their potential use as vehicles of bioactive compounds as food additives or pharmaceuticals.