Natural deep eutectic solvents: A green way to valorize plant products for cosmetic applications

Nowadays, it is no denying that plant extracts and pure phytochemicals, especially from the byproduct has been increasingly interested by both pharmaceutical and cosmetic industries. Furthermore, green chemistry and green technology is growing interested by the cosmetic and pharmaceutic sectors. Sea buckthorn pomace, obtained after the production of juice, is a valuable industrial by-product, because of its high amount of carotenoids, which may offer health advantages. The objectives were to develop and validate a green extraction process using ultrasound-assisted extraction (USAE) with deep natural eutectic solvents (NaDES) for the recovery of carotenoids from sea buckthorn fruit juice pomace. To achieve high extraction efficiency of carotenoids, a series of 10 different NADES were first evaluated. After this first evaluation phase, optimization of the extraction process was done with a NADES composed of caprylic and capric acids in a 3:1 ratio along with USAE. Both response surface methodology and the artificial neural network (ANN) model were used to investigate the significance of the extraction parameters, resulting in high predictive levels of carotenoid recovery. A maximum carotenoid yield of 25.34 mg per 100 g of dry material was reached under optimal process conditions, demonstrating the value of sea buckthorn pomace as a source of these bioactive compounds. The obtained extract included β-carotene and zeaxanthin as the major carotenoids, according to HPLC analysis. This USAE process, in addition to having the benefit of employing a green solvent, also provides a significant increase in extraction efficiency as compared to traditional maceration using either polar organic solvents (acetone) or non-polar organic solvents (petroleum ether). Finally, in vitro antioxidant and photooxidation protective assays show that this extract has a strong antioxidant potential against a variety of reactive radical species, as well as the ability to limit membrane lipid peroxidation and DNA oxidation in cellular context by scavenging reactive oxygen and nitrogen species formed during the photooxidation process. These results might facilitate the development of future functional food and/or cosmetic formulations employing sea buckthorn pomace.