Development of a green ultrasound-assisted method for the extraction of bioactive oils from sloe seeds: a sustainable alternative to Soxhlet extraction

Abstract

Prunus spinosa L. seed by-products produced during the generation of liqueur are gaining interest as an unexploited source of bioactive compounds. The objective of this study was to transform waste material into a high value added product by employing green procedures and solvents. Consequently, an experimental design was implemented to develop a sustainable ultrasound-assisted extraction (UAE) method, employing a mixture of ethanol and tert-butanol, for the recovery of bioactive oils from sloe seed residues. The oils were characterized in terms of fatty acid, tocopherol and polyphenol content using GC–MS, HPLC-DAD, and cLC-DAD-MS, respectively. Furthermore, the in vitro antimicrobial and antioxidant capacities were evaluated using spectrophotometric methods. The optimized UAE oil extraction method was found to be sustainable, as indicated by the AGREEprep results. Furthermore, this extraction method enabled the isolation of antioxidant oils (IC50 = 6.9 mg⋅L 1) with a higher amount of bioactive compounds (oleic acid, β + γ-tocopherols, gallic acid, and 2,3-dihydroxybenzoic acid) in comparison to conventional Soxhlet extraction. Specifically, the oil from sloe seeds after maceration (NBSAM) was rich in oleic acid (73.6 %), β + γ-tocopherol (100 mg⋅kg 1), gallic acid and 2,3-dihydroxybenzoic acid (271 and 25 μg⋅g 1, respectively). The chemometric study, using principal component analysis (PCA), allowed the correlation between the chemical composition of the oil and its oxidative stability (lasting 21 days) and effectiveness antimicrobial (with a minimum inhibitory concentration, MIC, of 20 mg⋅mL 1). In conclusion, an innovative and sustainable method for extracting seed oils from sloe residues has been developed. Moreover, NBSAM oil exhibited significant potential for feasible nutraceutical and cosmetic applications.