Microwave- and Ultrasound-Assisted Extraction of Cucurbita pepo Seeds: A Comparison Study of Antioxidant Activity, Phenolic Profile, and In-Vitro Cells Effects

Abstract

Nowadays there is a growing demand for nutraceuticals to prevent diseases related to redox imbalances, such as atherosclerosis and diabetes, being crucial to search for new matrixes rich in bioactive compounds. This work aims to characterize the value-added compounds extracted from Curcubita pepo seeds using green methodologies, namely microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE), employing water as an extracting solvent for two ratios (condition 1: 1 mg/20 mL; condition 2: 2.5 mg/20 mL). The extract with the best antioxidant/antiradical activity in FRAP (71.09 μmol FSE/g DW) and DPPH (5.08 mg TE/g DW) assays was MAE condition 1, while MAE condition 2 exhibited the highest activity in the ABTS assay (13.29 mg AAE/g DW) and TPC (16.89 mg GAE/g DW). A remarkable scavenging capacity was observed, particularly for HOCl, with IC50 values ranging from 1.88–13.50 μg/mL. A total of 21 phenolic compounds were identified, being catechin (4.567–7.354 mg/g DW), caffeine (1.147–2.401 mg/g DW) and gallic acid (0.945–1.337 mg/g DW) predominant. No adverse effects were observed on Caco-2 viability after exposure to MAE extracts, while the other conditions led to a slight viability decrease in NSC-34. These results highlighted that the extract from MAE condition 2 is the most promising as a potential nutraceutical ingredient.

Design of Experiments for Optimizing Ultrasound-Assisted Extraction of Bioactive Compounds from Plant-Based Sources

“…Additionally, the UAE method is versatile and can be employed with polar and non-polar solvents at different temperatures to enhance the yield of phytochemicals while reducing extraction time [4,16]. Furthermore, the ultrasound can be simultaneously applied with other extraction methods to improve the recovery efficiency of BC from plant-based materials, including heat [42], vacuum pressure [43], high pressure [44], enzyme [45], pulsed electric field [46], pressurized liquids [47], and microwave [48] among others. UAE has found successful application in a wide range of plant-based sources for recovering BC, including by-products from oranges, limes, and tangerines [49,50], Ficaria kochii flowers [51], Morus alba leaves [52], peaches and pumpkins [53], green tea leaves [54], Hibiscus sabdariffa calyces [55], and banana peel [56], among others [57][58][59].…”