Exploiting the Potential of Bioactive Molecules Extracted by Ultrasounds from Avocado Peels—Food and Nutraceutical Applications

Abstract

Natural bioactive compounds from food waste have fomented interest in food and pharmaceutical industries for the past decade. In this work, it purposed the recovery of bioactive avocado peel extract using an environmentally friendly technique: the ultrasound assisted extraction. The response surface methodology was applied in order to optimize the conditions of the extraction, ethanol-water mixtures and time. The optimized extracts (ethanol 38.46%, 44.06 min, and 50 °C) were chemically characterized by HPLC-ESI-MS and FTIR. Its antioxidant ability, as well as, its effect on cell metabolic activity of normal (L929) and cancer (Caco-2, A549 and HeLa) cell lines were assessed. Aqueous ethanol extracts presented a high content in bioactive compounds with high antioxidant potential. The most representative class of the phenolic compounds found in the avocado peel extract were phenolic acids, such as hydroxybenzoic and hydroxycinnamic acids. Another important chemical group detected were the flavonoids, such as flavanols, flavanonols, flavones, flavanones and chalcone, phenylethanoids and lignans. In terms of its influence on the metabolic activity of normal and cancer cell lines, the extract does not significantly affect normal cells. On the other hand, it can negatively affect cancer cells, particularly HeLa cells. These results clearly demonstrated that ultrasound is a sustainable extraction technique, resulting in extracts with low toxicity in normal cells and with potential application in food, pharmaceutical or nutraceutical sectors.

Deep Eutectic Solvents as a Green Tool for the Extraction of Bioactive Phenolic Compounds from Avocado Peels

“…On the other hand, when flavonoid content was evaluated, the maximum TFC values obtained for DES coincided wide DES 5 (211.73 ± 1.50 RE/g DAP) and DES 2 (186.01 ± 3.27 RE/g DAP), which have a 50% higher content of flavonoids than ethanol (94.70 ± 3.86 mg RE/g DAP). In our previous work with avocado peel [ 3 ], the maximum phenolic/flavonoid contents recovered by conventional solvents (water and ethanol) under optimal conditions (ethanol concentration of 38.46% ( v / v ) and 44.06 min) were TPC = 45.34 ± 1.7 mg GAE/g DAP and TFC = 87.56 ± 1.2 mg RE/g DAP. These values are significantly lower than those obtained for extraction performed by all the DES used in this work.…”

“…In all extracts, catechin represents between 65% and 76% of identified phenolic compounds. Besides catechin, the compounds rutin and epicatechin were previously found in extracts of avocado peel [ 3 , 30 ]. In the present samples, rutin was the second most abundant phenolic compound in all extracts.…”

“…The FRAP assay proved the potent reducing power of extracts obtained with DES, showing higher values for extracts obtained with DES 5, 2 and 1 (121.09 ± 8.9, 115.4 ± 7.5, and 107.32 ± 6.4 mg TE/g DAP, respectively). In our previous work with avocado peel, the optimized extract showed that in the FRAP assay the hydroethanolic extracts had values of 44.65 mg TE/g DAP [ 3 ]. This value is like the value obtained for the ethanol extract obtained in this work (46.37 ± 3.4 mg TE/g DAP), and lower than all extracts obtained with DES.…”

“…These residues account for 25% of the total fruit, and within these the peel itself accounts for between 11% and 17% [ 1 ]. Avocado peel is rich in polyphenols, including hydroxycinnamic and hydroxybenzoic acids, flavonoids, flavanols and others [ 3 ]. Moreover, numerous biological activities are associated with avocado peel extracts, such as antioxidant, anticancer, antibacterial, anti-inflammatory, anti-allergenic and anti-hypertensive proprieties [ 1 , 3 ].…”

Advances in Natural Antioxidants for Food Improvement

“…Avocado peels were also analyzed and bioactive molecules were extracted by ultrasounds with mixtures of ethanol and water. Phenolic acids (hydroxybenzoic and hydroxycinnamic acids) and flavonoids (flavanols, flavanonols, flavones, flavanones and chalcone), phenylethanoids and lignans were detected in peels [ 20 ]. In chocolate manufacturing, large amounts of by-products are produced from cocoa, which contains bioactive compounds, such as methylxanthines, flavonoids, procyanidins.…”